RF24.cpp

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/*
 Copyright (C) 2011 J. Coliz <maniacbug@ymail.com>
 
 This program is free software; you can redistribute it and/or
 modify it under the terms of the GNU General Public License
 version 2 as published by the Free Software Foundation.
 */
 
#include "nRF24L01.h"
#include "RF24_config.h"
#include "RF24.h"
 
/****************************************************************************/
 
void RF24::csn(bool mode)
{
#if defined(RF24_TINY)
    if (ce_pin != csn_pin) {
        digitalWrite(csn_pin, mode);
    }
    else {
        if (mode == HIGH) {
            PORTB |= (1 << PINB2);                         // SCK->CSN HIGH
            delayMicroseconds(RF24_CSN_SETTLE_HIGH_DELAY); // allow csn to settle.
        }
        else {
            PORTB &= ~(1 << PINB2);                       // SCK->CSN LOW
            delayMicroseconds(RF24_CSN_SETTLE_LOW_DELAY); // allow csn to settle
        }
    }
    // Return, CSN toggle complete
    return;
 
#elif defined(ARDUINO) && !defined(RF24_SPI_TRANSACTIONS)
    // Minimum ideal SPI bus speed is 2x data rate
    // If we assume 2Mbs data rate and 16Mhz clock, a
    // divider of 4 is the minimum we want.
    // CLK:BUS 8Mhz:2Mhz, 16Mhz:4Mhz, or 20Mhz:5Mhz
 
    #if !defined(SOFTSPI)
        // applies to SPI_UART and inherent hardware SPI
        #if defined(RF24_SPI_PTR)
    _spi->setBitOrder(MSBFIRST);
    _spi->setDataMode(SPI_MODE0);
 
            #if !defined(F_CPU) || F_CPU < 20000000
    _spi->setClockDivider(SPI_CLOCK_DIV2);
            #elif F_CPU < 40000000
    _spi->setClockDivider(SPI_CLOCK_DIV4);
            #elif F_CPU < 80000000
    _spi->setClockDivider(SPI_CLOCK_DIV8);
            #elif F_CPU < 160000000
    _spi->setClockDivider(SPI_CLOCK_DIV16);
            #elif F_CPU < 320000000
    _spi->setClockDivider(SPI_CLOCK_DIV32);
            #elif F_CPU < 640000000
    _spi->setClockDivider(SPI_CLOCK_DIV64);
            #elif F_CPU < 1280000000
    _spi->setClockDivider(SPI_CLOCK_DIV128);
            #else // F_CPU >= 1280000000
                #error "Unsupported CPU frequency. Please set correct SPI divider."
            #endif // F_CPU to SPI_CLOCK_DIV translation
 
        #else // !defined(RF24_SPI_PTR)
    _SPI.setBitOrder(MSBFIRST);
    _SPI.setDataMode(SPI_MODE0);
 
            #if !defined(F_CPU) || F_CPU < 20000000
    _SPI.setClockDivider(SPI_CLOCK_DIV2);
            #elif F_CPU < 40000000
    _SPI.setClockDivider(SPI_CLOCK_DIV4);
            #elif F_CPU < 80000000
    _SPI.setClockDivider(SPI_CLOCK_DIV8);
            #elif F_CPU < 160000000
    _SPI.setClockDivider(SPI_CLOCK_DIV16);
            #elif F_CPU < 320000000
    _SPI.setClockDivider(SPI_CLOCK_DIV32);
            #elif F_CPU < 640000000
    _SPI.setClockDivider(SPI_CLOCK_DIV64);
            #elif F_CPU < 1280000000
    _SPI.setClockDivider(SPI_CLOCK_DIV128);
            #else // F_CPU >= 1280000000
                #error "Unsupported CPU frequency. Please set correct SPI divider."
            #endif // F_CPU to SPI_CLOCK_DIV translation
        #endif     // !defined(RF24_SPI_PTR)
    #endif         // !defined(SOFTSPI)
 
#elif defined(RF24_RPi)
    if (!mode)
        _SPI.chipSelect(csn_pin);
#endif // defined(RF24_RPi)
 
#if !defined(RF24_LINUX)
    digitalWrite(csn_pin, mode);
    delayMicroseconds(csDelay);
#else
    static_cast<void>(mode); // ignore -Wunused-parameter
#endif // !defined(RF24_LINUX)
}
 
/****************************************************************************/
 
void RF24::ce(bool level)
{
#ifndef RF24_LINUX
    //Allow for 3-pin use on ATTiny
    if (ce_pin != csn_pin) {
#endif
        digitalWrite(ce_pin, level);
#ifndef RF24_LINUX
    }
#endif
}
 
/****************************************************************************/
 
inline void RF24::beginTransaction()
{
#if defined(RF24_SPI_TRANSACTIONS)
    #if defined(RF24_SPI_PTR)
        #if defined(RF24_RP2)
    _spi->beginTransaction(spi_speed);
        #else  // ! defined (RF24_RP2)
    _spi->beginTransaction(SPISettings(spi_speed, MSBFIRST, SPI_MODE0));
        #endif // ! defined (RF24_RP2)
    #else      // !defined(RF24_SPI_PTR)
    _SPI.beginTransaction(SPISettings(spi_speed, MSBFIRST, SPI_MODE0));
    #endif     // !defined(RF24_SPI_PTR)
#endif         // defined (RF24_SPI_TRANSACTIONS)
    csn(LOW);
}
 
/****************************************************************************/
 
inline void RF24::endTransaction()
{
    csn(HIGH);
#if defined(RF24_SPI_TRANSACTIONS)
    #if defined(RF24_SPI_PTR)
    _spi->endTransaction();
    #else  // !defined(RF24_SPI_PTR)
    _SPI.endTransaction();
    #endif // !defined(RF24_SPI_PTR)
#endif     // defined (RF24_SPI_TRANSACTIONS)
}
 
/****************************************************************************/
 
void RF24::read_register(uint8_t reg, uint8_t* buf, uint8_t len)
{
#if defined(RF24_LINUX) || defined(RF24_RP2)
    beginTransaction(); //configures the spi settings for RPi, locks mutex and setting csn low
    uint8_t* prx = spi_rxbuff;
    uint8_t* ptx = spi_txbuff;
    uint8_t size = static_cast<uint8_t>(len + 1); // Add register value to transmit buffer
 
    *ptx++ = reg;
 
    while (len--) {
        *ptx++ = nRF24L01::NOP; // Dummy operation, just for reading
    }
 
    #if defined(RF24_RP2)
    _spi->transfernb((const uint8_t*)spi_txbuff, spi_rxbuff, size);
    #else  // !defined (RF24_RP2)
    _SPI.transfernb(reinterpret_cast<char*>(spi_txbuff), reinterpret_cast<char*>(spi_rxbuff), size);
    #endif // !defined (RF24_RP2)
 
    status = *prx++; // status is 1st byte of receive buffer
 
    // decrement before to skip status byte
    while (--size) {
        *buf++ = *prx++;
    }
 
    endTransaction(); // unlocks mutex and setting csn high
 
#else // !defined(RF24_LINUX) && !defined(RF24_RP2)
 
    beginTransaction();
    #if defined(RF24_SPI_PTR)
    status = _spi->transfer(reg);
    while (len--) {
        *buf++ = _spi->transfer(0xFF);
    }
 
    #else // !defined(RF24_SPI_PTR)
    status = _SPI.transfer(reg);
    while (len--) {
        *buf++ = _SPI.transfer(0xFF);
    }
 
    #endif // !defined(RF24_SPI_PTR)
    endTransaction();
#endif     // !defined(RF24_LINUX) && !defined(RF24_RP2)
}
 
/****************************************************************************/
 
uint8_t RF24::read_register(uint8_t reg)
{
    uint8_t result;
 
#if defined(RF24_LINUX) || defined(RF24_RP2)
    beginTransaction();
 
    uint8_t* prx = spi_rxbuff;
    uint8_t* ptx = spi_txbuff;
    *ptx++ = reg;
    *ptx++ = nRF24L01::NOP; // Dummy operation, just for reading
 
    #if defined(RF24_RP2)
    _spi->transfernb((const uint8_t*)spi_txbuff, spi_rxbuff, 2);
    #else  // !defined(RF24_RP2)
    _SPI.transfernb(reinterpret_cast<char*>(spi_txbuff), reinterpret_cast<char*>(spi_rxbuff), 2);
    #endif // !defined(RF24_RP2)
 
    status = *prx;   // status is 1st byte of receive buffer
    result = *++prx; // result is 2nd byte of receive buffer
 
    endTransaction();
#else // !defined(RF24_LINUX) && !defined(RF24_RP2)
 
    beginTransaction();
    #if defined(RF24_SPI_PTR)
    status = _spi->transfer(reg);
    result = _spi->transfer(0xff);
 
    #else // !defined(RF24_SPI_PTR)
    status = _SPI.transfer(reg);
    result = _SPI.transfer(0xff);
 
    #endif // !defined(RF24_SPI_PTR)
    endTransaction();
#endif     // !defined(RF24_LINUX) && !defined(RF24_RP2)
 
    return result;
}
 
/****************************************************************************/
 
void RF24::write_register(uint8_t reg, const uint8_t* buf, uint8_t len)
{
#if defined(RF24_LINUX) || defined(RF24_RP2)
    beginTransaction();
    uint8_t* prx = spi_rxbuff;
    uint8_t* ptx = spi_txbuff;
    uint8_t size = static_cast<uint8_t>(len + 1); // Add register value to transmit buffer
 
    *ptx++ = (nRF24L01::W_REGISTER | reg);
    while (len--) {
        *ptx++ = *buf++;
    }
 
    #if defined(RF24_RP2)
    _spi->transfernb((const uint8_t*)spi_txbuff, spi_rxbuff, size);
    #else  // !defined(RF24_RP2)
    _SPI.transfernb(reinterpret_cast<char*>(spi_txbuff), reinterpret_cast<char*>(spi_rxbuff), size);
    #endif // !defined(RF24_RP2)
 
    status = *prx; // status is 1st byte of receive buffer
    endTransaction();
#else // !defined(RF24_LINUX) && !defined(RF24_RP2)
 
    beginTransaction();
    #if defined(RF24_SPI_PTR)
    status = _spi->transfer(nRF24L01::W_REGISTER | reg);
    while (len--) {
        _spi->transfer(*buf++);
    }
 
    #else // !defined(RF24_SPI_PTR)
    status = _SPI.transfer(nRF24L01::W_REGISTER | reg);
    while (len--) {
        _SPI.transfer(*buf++);
    }
 
    #endif // !defined(RF24_SPI_PTR)
    endTransaction();
#endif     // !defined(RF24_LINUX) && !defined(RF24_RP2)
}
 
/****************************************************************************/
 
void RF24::write_register(uint8_t reg, uint8_t value)
{
    IF_RF24_DEBUG(printf_P(PSTR("write_register(%02x,%02x)\r\n"), reg, value));
#if defined(RF24_LINUX) || defined(RF24_RP2)
    beginTransaction();
    uint8_t* prx = spi_rxbuff;
    uint8_t* ptx = spi_txbuff;
    *ptx++ = (nRF24L01::W_REGISTER | reg);
    *ptx = value;
 
    #if defined(RF24_RP2)
    _spi->transfernb((const uint8_t*)spi_txbuff, spi_rxbuff, 2);
    #else  // !defined(RF24_RP2)
    _SPI.transfernb(reinterpret_cast<char*>(spi_txbuff), reinterpret_cast<char*>(spi_rxbuff), 2);
    #endif // !defined(RF24_RP2)
 
    status = *prx++; // status is 1st byte of receive buffer
    endTransaction();
#else // !defined(RF24_LINUX) && !defined(RF24_RP2)
 
    beginTransaction();
    #if defined(RF24_SPI_PTR)
    status = _spi->transfer(nRF24L01::W_REGISTER | reg);
    _spi->transfer(value);
    #else  // !defined(RF24_SPI_PTR)
    status = _SPI.transfer(nRF24L01::W_REGISTER | reg);
    _SPI.transfer(value);
    #endif // !defined(RF24_SPI_PTR)
    endTransaction();
#endif     // !defined(RF24_LINUX) && !defined(RF24_RP2)
}
 
/****************************************************************************/
 
void RF24::write_payload(const void* buf, uint8_t data_len, const uint8_t writeType)
{
    const uint8_t* current = reinterpret_cast<const uint8_t*>(buf);
 
    uint8_t blank_len = !data_len ? 1 : 0;
    if (!dynamic_payloads_enabled) {
        data_len = rf24_min(data_len, payload_size);
        blank_len = static_cast<uint8_t>(payload_size - data_len);
    }
    else {
        data_len = rf24_min(data_len, static_cast<uint8_t>(32));
    }
 
    //printf("[Writing %u bytes %u blanks]",data_len,blank_len);
    IF_RF24_DEBUG(printf_P("[Writing %u bytes %u blanks]\n", data_len, blank_len););
 
#if defined(RF24_LINUX) || defined(RF24_RP2)
    beginTransaction();
    uint8_t* prx = spi_rxbuff;
    uint8_t* ptx = spi_txbuff;
    uint8_t size;
    size = static_cast<uint8_t>(data_len + blank_len + 1); // Add register value to transmit buffer
 
    *ptx++ = writeType;
    while (data_len--) {
        *ptx++ = *current++;
    }
 
    while (blank_len--) {
        *ptx++ = 0;
    }
 
    #if defined(RF24_RP2)
    _spi->transfernb((const uint8_t*)spi_txbuff, spi_rxbuff, size);
    #else  // !defined(RF24_RP2)
    _SPI.transfernb(reinterpret_cast<char*>(spi_txbuff), reinterpret_cast<char*>(spi_rxbuff), size);
    #endif // !defined(RF24_RP2)
 
    status = *prx; // status is 1st byte of receive buffer
    endTransaction();
 
#else // !defined(RF24_LINUX) && !defined(RF24_RP2)
 
    beginTransaction();
    #if defined(RF24_SPI_PTR)
    status = _spi->transfer(writeType);
    while (data_len--) {
        _spi->transfer(*current++);
    }
 
    while (blank_len--) {
        _spi->transfer(0);
    }
 
    #else // !defined(RF24_SPI_PTR)
    status = _SPI.transfer(writeType);
    while (data_len--) {
        _SPI.transfer(*current++);
    }
 
    while (blank_len--) {
        _SPI.transfer(0);
    }
 
    #endif // !defined(RF24_SPI_PTR)
    endTransaction();
#endif     // !defined(RF24_LINUX) && !defined(RF24_RP2)
}
 
/****************************************************************************/
 
void RF24::read_payload(void* buf, uint8_t data_len)
{
    uint8_t* current = reinterpret_cast<uint8_t*>(buf);
 
    uint8_t blank_len = 0;
    if (!dynamic_payloads_enabled) {
        data_len = rf24_min(data_len, payload_size);
        blank_len = static_cast<uint8_t>(payload_size - data_len);
    }
    else {
        data_len = rf24_min(data_len, static_cast<uint8_t>(32));
    }
 
    //printf("[Reading %u bytes %u blanks]",data_len,blank_len);
 
    IF_RF24_DEBUG(printf_P("[Reading %u bytes %u blanks]\n", data_len, blank_len););
 
#if defined(RF24_LINUX) || defined(RF24_RP2)
    beginTransaction();
    uint8_t* prx = spi_rxbuff;
    uint8_t* ptx = spi_txbuff;
    uint8_t size;
    size = static_cast<uint8_t>(data_len + blank_len + 1); // Add register value to transmit buffer
 
    *ptx++ = nRF24L01::R_RX_PAYLOAD;
    while (--size) {
        *ptx++ = nRF24L01::NOP;
    }
 
    size = static_cast<uint8_t>(data_len + blank_len + 1); // Size has been lost during while, re affect
 
    #if defined(RF24_RP2)
    _spi->transfernb((const uint8_t*)spi_txbuff, spi_rxbuff, size);
    #else  // !defined(RF24_RP2)
    _SPI.transfernb(reinterpret_cast<char*>(spi_txbuff), reinterpret_cast<char*>(spi_rxbuff), size);
    #endif // !defined(RF24_RP2)
 
    status = *prx++; // 1st byte is status
 
    if (data_len > 0) {
        // Decrement before to skip 1st status byte
        while (--data_len) {
            *current++ = *prx++;
        }
 
        *current = *prx;
    }
    endTransaction();
#else // !defined(RF24_LINUX) && !defined(RF24_RP2)
 
    beginTransaction();
    #if defined(RF24_SPI_PTR)
    status = _spi->transfer(nRF24L01::R_RX_PAYLOAD);
    while (data_len--) {
        *current++ = _spi->transfer(0xFF);
    }
 
    while (blank_len--) {
        _spi->transfer(0xFF);
    }
 
    #else // !defined(RF24_SPI_PTR)
    status = _SPI.transfer(nRF24L01::R_RX_PAYLOAD);
    while (data_len--) {
        *current++ = _SPI.transfer(0xFF);
    }
 
    while (blank_len--) {
        _SPI.transfer(0xff);
    }
 
    #endif // !defined(RF24_SPI_PTR)
    endTransaction();
 
#endif // !defined(RF24_LINUX) && !defined(RF24_RP2)
}
 
/****************************************************************************/
 
uint8_t RF24::flush_rx(void)
{
    read_register(nRF24L01::FLUSH_RX, (uint8_t*)nullptr, 0);
    IF_RF24_DEBUG(printf_P("[Flushing RX FIFO]"););
    return status;
}
 
/****************************************************************************/
 
uint8_t RF24::flush_tx(void)
{
    read_register(nRF24L01::FLUSH_TX, (uint8_t*)nullptr, 0);
    IF_RF24_DEBUG(printf_P("[Flushing RX FIFO]"););
    return status;
}
 
/****************************************************************************/
#if !defined(MINIMAL)
 
void RF24::printStatus(uint8_t flags)
{
    printf_P(PSTR("RX_DR=%x TX_DS=%x TX_DF=%x RX_PIPE=%x TX_FULL=%x\r\n"),
             (flags & RF24_RX_DR) ? 1 : 0,
             (flags & RF24_TX_DS) ? 1 : 0,
             (flags & RF24_TX_DF) ? 1 : 0,
             (flags >> nRF24L01::RX_P_NO) & 0x07,
             (flags & _BV(nRF24L01::TX_FULL)) ? 1 : 0);
}
 
/****************************************************************************/
 
void RF24::print_observe_tx(uint8_t value)
{
    printf_P(PSTR("OBSERVE_TX=%02x: PLOS_CNT=%x ARC_CNT=%x\r\n"), value, (value >> nRF24L01::PLOS_CNT) & 0x0F, (value >> nRF24L01::ARC_CNT) & 0x0F);
}
 
/****************************************************************************/
 
void RF24::print_byte_register(const char* name, uint8_t reg, uint8_t qty)
{
    printf_P(PSTR(PRIPSTR
                  "\t="),
             name);
    while (qty--) {
        printf_P(PSTR(" 0x%02x"), read_register(reg++));
    }
    printf_P(PSTR("\r\n"));
}
 
/****************************************************************************/
 
void RF24::print_address_register(const char* name, uint8_t reg, uint8_t qty)
{
 
    printf_P(PSTR(PRIPSTR
                  "\t="),
             name);
    while (qty--) {
        uint8_t* buffer = new uint8_t[addr_width];
        read_register(reg++, buffer, addr_width);
 
        printf_P(PSTR(" 0x"));
        uint8_t* bufptr = buffer + addr_width;
        while (--bufptr >= buffer) {
            printf_P(PSTR("%02x"), *bufptr); // NOLINT: clang-tidy seems to emit a false positive about zero-allocated memory here (*bufptr)
        }
        delete[] buffer;
    }
    printf_P(PSTR("\r\n"));
}
 
/****************************************************************************/
 
uint8_t RF24::sprintf_address_register(char* out_buffer, uint8_t reg, uint8_t qty)
{
    uint8_t offset = 0;
    uint8_t* read_buffer = new uint8_t[addr_width];
    while (qty--) {
        read_register(reg++, read_buffer, addr_width);
        uint8_t* bufptr = read_buffer + addr_width;
        while (--bufptr >= read_buffer) {
            offset += sprintf_P(out_buffer + offset, PSTR("%02X"), *bufptr); // NOLINT(clang-analyzer-cplusplus.NewDelete)
        }
    }
    delete[] read_buffer;
    return offset;
}
#endif // !defined(MINIMAL)
 
/****************************************************************************/
 
RF24::RF24(rf24_gpio_pin_t _cepin, rf24_gpio_pin_t _cspin, uint32_t _spi_speed)
    : ce_pin(_cepin),
      csn_pin(_cspin),
      spi_speed(_spi_speed),
      payload_size(32),
      _is_p_variant(false),
      _is_p0_rx(false),
      addr_width(5),
      dynamic_payloads_enabled(true),
#if defined FAILURE_HANDLING
      failureDetected(0),
#endif
      csDelay(5)
{
    _init_obj();
}
 
/****************************************************************************/
 
RF24::RF24(uint32_t _spi_speed)
    : ce_pin(RF24_PIN_INVALID),
      csn_pin(RF24_PIN_INVALID),
      spi_speed(_spi_speed),
      payload_size(32),
      _is_p_variant(false),
      _is_p0_rx(false),
      addr_width(5),
      dynamic_payloads_enabled(true),
#if defined FAILURE_HANDLING
      failureDetected(0),
#endif
      csDelay(5)
{
    _init_obj();
}
 
/****************************************************************************/
 
void RF24::_init_obj()
{
    // Use a pointer on the Arduino platform
 
#if defined(RF24_SPI_PTR) && !defined(RF24_RP2)
    _spi = &SPI;
#endif // defined (RF24_SPI_PTR)
 
    if (spi_speed <= 35000) { //Handle old BCM2835 speed constants, default to RF24_SPI_SPEED
        spi_speed = RF24_SPI_SPEED;
    }
}
 
/****************************************************************************/
 
void RF24::setChannel(uint8_t channel)
{
    const uint8_t max_channel = 125;
    write_register(nRF24L01::RF_CH, rf24_min(channel, max_channel));
}
 
uint8_t RF24::getChannel()
{
    return read_register(nRF24L01::RF_CH);
}
 
/****************************************************************************/
 
void RF24::setPayloadSize(uint8_t size)
{
    // payload size must be in range [1, 32]
    payload_size = static_cast<uint8_t>(rf24_max(1, rf24_min(32, size)));
 
    // write static payload size setting for all pipes
    for (uint8_t i = 0; i < 6; ++i) {
        write_register(static_cast<uint8_t>(nRF24L01::RX_PW_P0 + i), payload_size);
    }
}
 
/****************************************************************************/
 
uint8_t RF24::getPayloadSize(void)
{
    return payload_size;
}
 
/****************************************************************************/
 
#if !defined(MINIMAL)
 
static const PROGMEM char rf24_datarate_e_str_0[] = "= 1 MBPS";
static const PROGMEM char rf24_datarate_e_str_1[] = "= 2 MBPS";
static const PROGMEM char rf24_datarate_e_str_2[] = "= 250 KBPS";
static const PROGMEM char* const rf24_datarate_e_str_P[] = {
    rf24_datarate_e_str_0,
    rf24_datarate_e_str_1,
    rf24_datarate_e_str_2,
};
static const PROGMEM char rf24_model_e_str_0[] = "nRF24L01";
static const PROGMEM char rf24_model_e_str_1[] = "nRF24L01+";
static const PROGMEM char* const rf24_model_e_str_P[] = {
    rf24_model_e_str_0,
    rf24_model_e_str_1,
};
static const PROGMEM char rf24_crclength_e_str_0[] = "= Disabled";
static const PROGMEM char rf24_crclength_e_str_1[] = "= 8 bits";
static const PROGMEM char rf24_crclength_e_str_2[] = "= 16 bits";
static const PROGMEM char* const rf24_crclength_e_str_P[] = {
    rf24_crclength_e_str_0,
    rf24_crclength_e_str_1,
    rf24_crclength_e_str_2,
};
static const PROGMEM char rf24_pa_dbm_e_str_0[] = "= PA_MIN";
static const PROGMEM char rf24_pa_dbm_e_str_1[] = "= PA_LOW";
static const PROGMEM char rf24_pa_dbm_e_str_2[] = "= PA_HIGH";
static const PROGMEM char rf24_pa_dbm_e_str_3[] = "= PA_MAX";
static const PROGMEM char* const rf24_pa_dbm_e_str_P[] = {
    rf24_pa_dbm_e_str_0,
    rf24_pa_dbm_e_str_1,
    rf24_pa_dbm_e_str_2,
    rf24_pa_dbm_e_str_3,
};
 
static const PROGMEM char rf24_feature_e_str_on[] = "= Enabled";
static const PROGMEM char rf24_feature_e_str_allowed[] = "= Allowed";
static const PROGMEM char rf24_feature_e_str_open[] = " open ";
static const PROGMEM char rf24_feature_e_str_closed[] = "closed";
static const PROGMEM char* const rf24_feature_e_str_P[] = {
    rf24_crclength_e_str_0,
    rf24_feature_e_str_on,
    rf24_feature_e_str_allowed,
    rf24_feature_e_str_closed,
    rf24_feature_e_str_open,
};
 
void RF24::printDetails(void)
{
 
    #if defined(RF24_LINUX)
    printf("================ SPI Configuration ================\n");
    uint8_t bus_ce = static_cast<uint8_t>(csn_pin % 10);
    uint8_t bus_numb = static_cast<uint8_t>((csn_pin - bus_ce) / 10);
    printf("CSN Pin\t\t= /dev/spidev%d.%d\n", bus_numb, bus_ce);
    printf("CE Pin\t\t= Custom GPIO%d\n", ce_pin);
    #endif
    printf_P(PSTR("SPI Speedz\t= %d Mhz\n"), static_cast<uint8_t>(spi_speed / 1000000)); //Print the SPI speed on non-Linux devices
    #if defined(RF24_LINUX)
    printf("================ NRF Configuration ================\n");
    #endif // defined(RF24_LINUX)
 
    uint8_t status = update();
    printf_P(PSTR("STATUS\t\t= 0x%02x "), status);
    printStatus(status);
 
    print_address_register(PSTR("RX_ADDR_P0-1"), nRF24L01::RX_ADDR_P0, 2);
    print_byte_register(PSTR("RX_ADDR_P2-5"), nRF24L01::RX_ADDR_P2, 4);
    print_address_register(PSTR("TX_ADDR\t"), nRF24L01::TX_ADDR);
 
    print_byte_register(PSTR("RX_PW_P0-6"), nRF24L01::RX_PW_P0, 6);
    print_byte_register(PSTR("EN_AA\t"), nRF24L01::EN_AA);
    print_byte_register(PSTR("EN_RXADDR"), nRF24L01::EN_RXADDR);
    print_byte_register(PSTR("RF_CH\t"), nRF24L01::RF_CH);
    print_byte_register(PSTR("RF_SETUP"), nRF24L01::RF_SETUP);
    print_byte_register(PSTR("CONFIG\t"), nRF24L01::CONFIG);
    print_byte_register(PSTR("DYNPD/FEATURE"), nRF24L01::DYNPD, 2);
 
    printf_P(PSTR("Data Rate\t" PRIPSTR
                  "\r\n"),
             (char*)(pgm_read_ptr(&rf24_datarate_e_str_P[getDataRate()])));
    printf_P(PSTR("Model\t\t= " PRIPSTR
                  "\r\n"),
             (char*)(pgm_read_ptr(&rf24_model_e_str_P[isPVariant()])));
    printf_P(PSTR("CRC Length\t" PRIPSTR
                  "\r\n"),
             (char*)(pgm_read_ptr(&rf24_crclength_e_str_P[getCRCLength()])));
    printf_P(PSTR("PA Power\t" PRIPSTR
                  "\r\n"),
             (char*)(pgm_read_ptr(&rf24_pa_dbm_e_str_P[getPALevel()])));
    printf_P(PSTR("ARC\t\t= %d\r\n"), getARC());
}
 
void RF24::printPrettyDetails(void)
{
 
    #if defined(RF24_LINUX)
    printf("================ SPI Configuration ================\n");
    uint8_t bus_ce = static_cast<uint8_t>(csn_pin % 10);
    uint8_t bus_numb = static_cast<uint8_t>((csn_pin - bus_ce) / 10);
    printf("CSN Pin\t\t\t= /dev/spidev%d.%d\n", bus_numb, bus_ce);
    printf("CE Pin\t\t\t= Custom GPIO%d\n", ce_pin);
    #endif
    printf_P(PSTR("SPI Frequency\t\t= %d Mhz\n"), static_cast<uint8_t>(spi_speed / 1000000)); //Print the SPI speed on non-Linux devices
    #if defined(RF24_LINUX)
    printf("================ NRF Configuration ================\n");
    #endif // defined(RF24_LINUX)
 
    uint8_t channel = getChannel();
    uint16_t frequency = static_cast<uint16_t>(channel + 2400);
    printf_P(PSTR("Channel\t\t\t= %u (~ %u MHz)\r\n"), channel, frequency);
    printf_P(PSTR("Model\t\t\t= " PRIPSTR
                  "\r\n"),
             (char*)(pgm_read_ptr(&rf24_model_e_str_P[isPVariant()])));
 
    printf_P(PSTR("RF Data Rate\t\t" PRIPSTR
                  "\r\n"),
             (char*)(pgm_read_ptr(&rf24_datarate_e_str_P[getDataRate()])));
    printf_P(PSTR("RF Power Amplifier\t" PRIPSTR
                  "\r\n"),
             (char*)(pgm_read_ptr(&rf24_pa_dbm_e_str_P[getPALevel()])));
    printf_P(PSTR("RF Low Noise Amplifier\t" PRIPSTR
                  "\r\n"),
             (char*)(pgm_read_ptr(&rf24_feature_e_str_P[static_cast<uint8_t>((read_register(nRF24L01::RF_SETUP) & 1) * 1)])));
    printf_P(PSTR("CRC Length\t\t" PRIPSTR
                  "\r\n"),
             (char*)(pgm_read_ptr(&rf24_crclength_e_str_P[getCRCLength()])));
    printf_P(PSTR("Address Length\t\t= %d bytes\r\n"), (read_register(nRF24L01::SETUP_AW) & 3) + 2);
    printf_P(PSTR("Static Payload Length\t= %d bytes\r\n"), getPayloadSize());
 
    uint8_t setupRetry = read_register(nRF24L01::SETUP_RETR);
    printf_P(PSTR("Auto Retry Delay\t= %d microseconds\r\n"), (setupRetry >> nRF24L01::ARD) * 250 + 250);
    printf_P(PSTR("Auto Retry Attempts\t= %d maximum\r\n"), setupRetry & 0x0F);
 
    uint8_t observeTx = read_register(nRF24L01::OBSERVE_TX);
    printf_P(PSTR("Packets lost on\n    current channel\t= %d\r\n"), observeTx >> 4);
    printf_P(PSTR("Retry attempts made for\n    last transmission\t= %d\r\n"), observeTx & 0x0F);
 
    uint8_t features = read_register(nRF24L01::FEATURE);
    printf_P(PSTR("Multicast\t\t" PRIPSTR
                  "\r\n"),
             (char*)(pgm_read_ptr(&rf24_feature_e_str_P[static_cast<uint8_t>(static_cast<bool>(features & _BV(nRF24L01::EN_DYN_ACK)) * 2)])));
    printf_P(PSTR("Custom ACK Payload\t" PRIPSTR
                  "\r\n"),
             (char*)(pgm_read_ptr(&rf24_feature_e_str_P[static_cast<uint8_t>(static_cast<bool>(features & _BV(nRF24L01::EN_ACK_PAY)) * 1)])));
 
    uint8_t dynPl = read_register(nRF24L01::DYNPD);
    printf_P(PSTR("Dynamic Payloads\t" PRIPSTR
                  "\r\n"),
             (char*)(pgm_read_ptr(&rf24_feature_e_str_P[static_cast<uint8_t>((dynPl && (features & _BV(nRF24L01::EN_DPL))) * 1)])));
 
    uint8_t autoAck = read_register(nRF24L01::EN_AA);
    if (autoAck == 0x3F || autoAck == 0) {
        // all pipes have the same configuration about auto-ack feature
        printf_P(PSTR("Auto Acknowledgment\t" PRIPSTR
                      "\r\n"),
                 (char*)(pgm_read_ptr(&rf24_feature_e_str_P[static_cast<uint8_t>(static_cast<bool>(autoAck) * 1)])));
    }
    else {
        // representation per pipe
        printf_P(PSTR("Auto Acknowledgment\t= 0b%c%c%c%c%c%c\r\n"),
                 static_cast<char>(static_cast<bool>(autoAck & _BV(nRF24L01::ENAA_P5)) + 48),
                 static_cast<char>(static_cast<bool>(autoAck & _BV(nRF24L01::ENAA_P4)) + 48),
                 static_cast<char>(static_cast<bool>(autoAck & _BV(nRF24L01::ENAA_P3)) + 48),
                 static_cast<char>(static_cast<bool>(autoAck & _BV(nRF24L01::ENAA_P2)) + 48),
                 static_cast<char>(static_cast<bool>(autoAck & _BV(nRF24L01::ENAA_P1)) + 48),
                 static_cast<char>(static_cast<bool>(autoAck & _BV(nRF24L01::ENAA_P0)) + 48));
    }
 
    config_reg = read_register(nRF24L01::CONFIG);
    printf_P(PSTR("Primary Mode\t\t= %cX\r\n"), config_reg & _BV(nRF24L01::PRIM_RX) ? 'R' : 'T');
    print_address_register(PSTR("TX address\t"), nRF24L01::TX_ADDR);
 
    uint8_t openPipes = read_register(nRF24L01::EN_RXADDR);
    for (uint8_t i = 0; i < 6; ++i) {
        bool isOpen = openPipes & _BV(i);
        printf_P(PSTR("pipe %u (" PRIPSTR
                      ") bound"),
                 i, (char*)(pgm_read_ptr(&rf24_feature_e_str_P[isOpen + 3])));
        if (i < 2) {
            print_address_register(PSTR(""), static_cast<uint8_t>(nRF24L01::RX_ADDR_P0 + i));
        }
        else {
            print_byte_register(PSTR(""), static_cast<uint8_t>(nRF24L01::RX_ADDR_P0 + i));
        }
    }
}
 
/****************************************************************************/
 
uint16_t RF24::sprintfPrettyDetails(char* debugging_information)
{
    const char* format_string = PSTR(
        "================ SPI Configuration ================\n"
        "CSN Pin\t\t\t= %d\n"
        "CE Pin\t\t\t= %d\n"
        "SPI Frequency\t\t= %d Mhz\n"
        "================ NRF Configuration ================\n"
        "Channel\t\t\t= %u (~ %u MHz)\n"
        "RF Data Rate\t\t" PRIPSTR "\n"
        "RF Power Amplifier\t" PRIPSTR "\n"
        "RF Low Noise Amplifier\t" PRIPSTR "\n"
        "CRC Length\t\t" PRIPSTR "\n"
        "Address Length\t\t= %d bytes\n"
        "Static Payload Length\t= %d bytes\n"
        "Auto Retry Delay\t= %d microseconds\n"
        "Auto Retry Attempts\t= %d maximum\n"
        "Packets lost on\n    current channel\t= %d\r\n"
        "Retry attempts made for\n    last transmission\t= %d\r\n"
        "Multicast\t\t" PRIPSTR "\n"
        "Custom ACK Payload\t" PRIPSTR "\n"
        "Dynamic Payloads\t" PRIPSTR "\n"
        "Auto Acknowledgment\t");
    const char* format_str2 = PSTR("\nPrimary Mode\t\t= %cX\nTX address\t\t= 0x");
    const char* format_str3 = PSTR("\nPipe %d (" PRIPSTR ") bound\t= 0x");
 
    uint16_t offset = sprintf_P(
        debugging_information, format_string, csn_pin, ce_pin,
        static_cast<uint8_t>(spi_speed / 1000000), getChannel(),
        static_cast<uint16_t>(getChannel() + 2400),
        (char*)(pgm_read_ptr(&rf24_datarate_e_str_P[getDataRate()])),
        (char*)(pgm_read_ptr(&rf24_pa_dbm_e_str_P[getPALevel()])),
        (char*)(pgm_read_ptr(&rf24_feature_e_str_P[static_cast<uint8_t>((read_register(nRF24L01::RF_SETUP) & 1) * 1)])),
        (char*)(pgm_read_ptr(&rf24_crclength_e_str_P[getCRCLength()])),
        ((read_register(nRF24L01::SETUP_AW) & 3) + 2), getPayloadSize(),
        ((read_register(nRF24L01::SETUP_RETR) >> nRF24L01::ARD) * 250 + 250),
        (read_register(nRF24L01::SETUP_RETR) & 0x0F), (read_register(nRF24L01::OBSERVE_TX) >> 4),
        (read_register(nRF24L01::OBSERVE_TX) & 0x0F),
        (char*)(pgm_read_ptr(&rf24_feature_e_str_P[static_cast<uint8_t>(static_cast<bool>(read_register(nRF24L01::FEATURE) & _BV(nRF24L01::EN_DYN_ACK)) * 2)])),
        (char*)(pgm_read_ptr(&rf24_feature_e_str_P[static_cast<uint8_t>(static_cast<bool>(read_register(nRF24L01::FEATURE) & _BV(nRF24L01::EN_ACK_PAY)) * 1)])),
        (char*)(pgm_read_ptr(&rf24_feature_e_str_P[static_cast<uint8_t>((read_register(nRF24L01::DYNPD) && (read_register(nRF24L01::FEATURE) & _BV(nRF24L01::EN_DPL))) * 1)])));
    uint8_t autoAck = read_register(nRF24L01::EN_AA);
    if (autoAck == 0x3F || autoAck == 0) {
        // all pipes have the same configuration about auto-ack feature
        offset += sprintf_P(
            debugging_information + offset, PSTR("" PRIPSTR ""),
            (char*)(pgm_read_ptr(&rf24_feature_e_str_P[static_cast<uint8_t>(static_cast<bool>(autoAck) * 1)])));
    }
    else {
        // representation per pipe
        offset += sprintf_P(
            debugging_information + offset, PSTR("= 0b%c%c%c%c%c%c"),
            static_cast<char>(static_cast<bool>(autoAck & _BV(nRF24L01::ENAA_P5)) + 48),
            static_cast<char>(static_cast<bool>(autoAck & _BV(nRF24L01::ENAA_P4)) + 48),
            static_cast<char>(static_cast<bool>(autoAck & _BV(nRF24L01::ENAA_P3)) + 48),
            static_cast<char>(static_cast<bool>(autoAck & _BV(nRF24L01::ENAA_P2)) + 48),
            static_cast<char>(static_cast<bool>(autoAck & _BV(nRF24L01::ENAA_P1)) + 48),
            static_cast<char>(static_cast<bool>(autoAck & _BV(nRF24L01::ENAA_P0)) + 48));
    }
    offset += sprintf_P(
        debugging_information + offset, format_str2,
        (read_register(nRF24L01::CONFIG) & _BV(nRF24L01::PRIM_RX) ? 'R' : 'T'));
    offset += sprintf_address_register(debugging_information + offset, nRF24L01::TX_ADDR);
    uint8_t openPipes = read_register(nRF24L01::EN_RXADDR);
    for (uint8_t i = 0; i < 6; ++i) {
        offset += sprintf_P(
            debugging_information + offset, format_str3,
            i, ((char*)(pgm_read_ptr(&rf24_feature_e_str_P[static_cast<bool>(openPipes & _BV(i)) + 3]))));
        if (i < 2) {
            offset += sprintf_address_register(
                debugging_information + offset, static_cast<uint8_t>(nRF24L01::RX_ADDR_P0 + i));
        }
        else {
            offset += sprintf_P(
                debugging_information + offset, PSTR("%02X"),
                read_register(static_cast<uint8_t>(nRF24L01::RX_ADDR_P0 + i)));
        }
    }
    return offset;
}
 
/****************************************************************************/
 
void RF24::encodeRadioDetails(uint8_t* encoded_details)
{
    uint8_t end = nRF24L01::FEATURE + 1;
    for (uint8_t i = nRF24L01::CONFIG; i < end; ++i) {
        if (i == nRF24L01::RX_ADDR_P0 || i == nRF24L01::RX_ADDR_P1 || i == nRF24L01::TX_ADDR) {
            // get 40-bit registers
            read_register(i, encoded_details, 5);
            encoded_details += 5;
        }
        else if (i != 0x18 && i != 0x19 && i != 0x1a && i != 0x1b) { // skip undocumented registers
            // get single byte registers
            *encoded_details++ = read_register(i);
        }
    }
    *encoded_details++ = ce_pin >> 4;
    *encoded_details++ = ce_pin & 0xFF;
    *encoded_details++ = csn_pin >> 4;
    *encoded_details++ = csn_pin & 0xFF;
    *encoded_details = static_cast<uint8_t>((spi_speed / 1000000) | _BV(_is_p_variant * 4));
}
#endif // !defined(MINIMAL)
 
/****************************************************************************/
#if defined(RF24_SPI_PTR) || defined(DOXYGEN_FORCED)
// does not apply to RF24_LINUX
 
bool RF24::begin(_SPI* spiBus)
{
    _spi = spiBus;
    return _init_pins() && _init_radio();
}
 
/****************************************************************************/
 
bool RF24::begin(_SPI* spiBus, rf24_gpio_pin_t _cepin, rf24_gpio_pin_t _cspin)
{
    ce_pin = _cepin;
    csn_pin = _cspin;
    return begin(spiBus);
}
 
#endif // defined (RF24_SPI_PTR) || defined (DOXYGEN_FORCED)
 
/****************************************************************************/
 
bool RF24::begin(rf24_gpio_pin_t _cepin, rf24_gpio_pin_t _cspin)
{
    ce_pin = _cepin;
    csn_pin = _cspin;
    return begin();
}
 
/****************************************************************************/
 
bool RF24::begin(void)
{
#if defined(RF24_LINUX)
    #if defined(RF24_RPi)
    switch (csn_pin) { // Ensure valid hardware CS pin
        case 0: break;
        case 1: break;
        // Allow BCM2835 enums for RPi
        case 8: csn_pin = 0; break;
        case 7: csn_pin = 1; break;
        case 18: csn_pin = 10; break; // to make it work on SPI1
        case 17: csn_pin = 11; break;
        case 16: csn_pin = 12; break;
        default: csn_pin = 0; break;
    }
    #endif // RF24_RPi
 
    _SPI.begin(csn_pin, spi_speed);
 
#elif defined(XMEGA_D3)
    _spi->begin(csn_pin);
 
#elif defined(RF24_RP2)
    _spi = new SPI();
    _spi->begin(PICO_DEFAULT_SPI ? spi1 : spi0);
 
#else // using an Arduino platform || defined (LITTLEWIRE)
 
    #if defined(RF24_SPI_PTR)
    _spi->begin();
    #else  // !defined(RF24_SPI_PTR)
    _SPI.begin();
    #endif // !defined(RF24_SPI_PTR)
 
#endif // !defined(XMEGA_D3) && !defined(RF24_LINUX)
 
    return _init_pins() && _init_radio();
}
 
/****************************************************************************/
 
bool RF24::_init_pins()
{
    if (!isValid()) {
        // didn't specify the CSN & CE pins to c'tor nor begin()
        return false;
    }
 
#if defined(RF24_LINUX)
 
    pinMode(ce_pin, OUTPUT);
    ce(LOW);
    delay(100);
 
#elif defined(LITTLEWIRE)
    pinMode(csn_pin, OUTPUT);
    csn(HIGH);
 
#elif defined(XMEGA_D3)
    if (ce_pin != csn_pin) {
        pinMode(ce_pin, OUTPUT);
    };
    ce(LOW);
    csn(HIGH);
    delay(200);
 
#else // using an Arduino platform
 
    // Initialize pins
    if (ce_pin != csn_pin) {
        pinMode(ce_pin, OUTPUT);
        pinMode(csn_pin, OUTPUT);
    }
 
    ce(LOW);
    csn(HIGH);
 
    #if defined(__ARDUINO_X86__)
    delay(100);
    #endif
#endif // !defined(XMEGA_D3) && !defined(LITTLEWIRE) && !defined(RF24_LINUX)
 
    return true; // assuming pins are connected properly
}
 
/****************************************************************************/
 
bool RF24::_init_radio()
{
    // Must allow the radio time to settle else configuration bits will not necessarily stick.
    // This is actually only required following power up but some settling time also appears to
    // be required after resets too. For full coverage, we'll always assume the worst.
    // Enabling 16b CRC is by far the most obvious case if the wrong timing is used - or skipped.
    // Technically we require 4.5ms + 14us as a worst case. We'll just call it 5ms for good measure.
    // WARNING: Delay is based on P-variant whereby non-P *may* require different timing.
    delay(5);
 
    // Set 1500uS (minimum for 32B payload in ESB@250KBPS) timeouts, to make testing a little easier
    // WARNING: If this is ever lowered, either 250KBS mode with AA is broken or maximum packet
    // sizes must never be used. See datasheet for a more complete explanation.
    setRetries(5, 15);
 
    // Then set the data rate to the slowest (and most reliable) speed supported by all hardware.
    setDataRate(RF24_1MBPS);
 
    // detect if is a plus variant & use old toggle features command accordingly
    uint8_t before_toggle = read_register(nRF24L01::FEATURE);
    toggle_features();
    uint8_t after_toggle = read_register(nRF24L01::FEATURE);
    _is_p_variant = before_toggle == after_toggle;
    if (after_toggle) {
        if (_is_p_variant) {
            // module did not experience power-on-reset (#401)
            toggle_features();
        }
        // allow use of multicast parameter and dynamic payloads by default
        write_register(nRF24L01::FEATURE, 0);
    }
    ack_payloads_enabled = false;       // ack payloads disabled by default
    write_register(nRF24L01::DYNPD, 0); // disable dynamic payloads by default (for all pipes)
    dynamic_payloads_enabled = false;
    write_register(nRF24L01::EN_AA, 0x3F);  // enable auto-ack on all pipes
    write_register(nRF24L01::EN_RXADDR, 3); // only open RX pipes 0 & 1
    setPayloadSize(32);                     // set static payload size to 32 (max) bytes by default
    setAddressWidth(5);                     // set default address length to (max) 5 bytes
 
    // Set up default configuration.  Callers can always change it later.
    // This channel should be universally safe and not bleed over into adjacent
    // spectrum.
    setChannel(76);
 
    // Reset current status
    // Notice reset and flush is the last thing we do
    write_register(nRF24L01::STATUS, RF24_IRQ_ALL);
 
    // Flush buffers
    flush_rx();
    flush_tx();
 
    // Clear CONFIG register:
    //      Reflect NO IRQ events on IRQ pin
    //      Enable PTX
    //      Power Up
    //      16-bit CRC (CRC required by auto-ack)
    // Do not write CE high so radio will remain in standby I mode
    // PTX should use only 22uA of power
    write_register(nRF24L01::CONFIG, (_BV(nRF24L01::EN_CRC) | _BV(nRF24L01::CRCO) | _BV(nRF24L01::MASK_RX_DR) | _BV(nRF24L01::MASK_TX_DS) | _BV(nRF24L01::MASK_MAX_RT)));
    config_reg = read_register(nRF24L01::CONFIG);
 
    powerUp();
 
    // if config is not set correctly then there was a bad response from module
    return config_reg == (_BV(nRF24L01::EN_CRC) | _BV(nRF24L01::CRCO) | _BV(nRF24L01::PWR_UP) | _BV(nRF24L01::MASK_RX_DR) | _BV(nRF24L01::MASK_TX_DS) | _BV(nRF24L01::MASK_MAX_RT)) ? true : false;
}
 
/****************************************************************************/
 
bool RF24::isChipConnected()
{
    return read_register(nRF24L01::SETUP_AW) == (addr_width - static_cast<uint8_t>(2));
}
 
/****************************************************************************/
 
bool RF24::isValid()
{
    return ce_pin != RF24_PIN_INVALID && csn_pin != RF24_PIN_INVALID;
}
 
/****************************************************************************/
 
void RF24::startListening(void)
{
#if !defined(RF24_TINY) && !defined(LITTLEWIRE)
    powerUp();
#endif
    config_reg |= _BV(nRF24L01::PRIM_RX);
    write_register(nRF24L01::CONFIG, config_reg);
    write_register(nRF24L01::STATUS, RF24_IRQ_ALL);
    ce(HIGH);
 
    // Restore the pipe0 address, if exists
    if (_is_p0_rx) {
        write_register(nRF24L01::RX_ADDR_P0, pipe0_reading_address, addr_width);
    }
    else {
        closeReadingPipe(0);
    }
}
 
/****************************************************************************/
 
static const PROGMEM uint8_t child_pipe_enable[] = {nRF24L01::ERX_P0, nRF24L01::ERX_P1, nRF24L01::ERX_P2,
                                                    nRF24L01::ERX_P3, nRF24L01::ERX_P4, nRF24L01::ERX_P5};
 
void RF24::stopListening(void)
{
    ce(LOW);
 
    //delayMicroseconds(100);
    delayMicroseconds(static_cast<int>(txDelay));
    if (ack_payloads_enabled) {
        flush_tx();
    }
 
    config_reg = static_cast<uint8_t>(config_reg & ~_BV(nRF24L01::PRIM_RX));
    write_register(nRF24L01::CONFIG, config_reg);
 
#if defined(RF24_TINY) || defined(LITTLEWIRE)
    // for 3 pins solution TX mode is only left with additional powerDown/powerUp cycle
    if (ce_pin == csn_pin) {
        powerDown();
        powerUp();
    }
#endif
    write_register(nRF24L01::RX_ADDR_P0, pipe0_writing_address, addr_width);
    write_register(nRF24L01::EN_RXADDR, static_cast<uint8_t>(read_register(nRF24L01::EN_RXADDR) | _BV(pgm_read_byte(&child_pipe_enable[0])))); // Enable RX on pipe0
}
 
/****************************************************************************/
 
void RF24::stopListening(const uint64_t txAddress)
{
    memcpy(pipe0_writing_address, &txAddress, addr_width);
    stopListening();
    write_register(nRF24L01::TX_ADDR, pipe0_writing_address, addr_width);
}
 
/****************************************************************************/
 
void RF24::stopListening(const uint8_t* txAddress)
{
    memcpy(pipe0_writing_address, txAddress, addr_width);
    stopListening();
    write_register(nRF24L01::TX_ADDR, pipe0_writing_address, addr_width);
}
 
/****************************************************************************/
 
void RF24::powerDown(void)
{
    ce(LOW); // Guarantee CE is low on powerDown
    config_reg = static_cast<uint8_t>(config_reg & ~_BV(nRF24L01::PWR_UP));
    write_register(nRF24L01::CONFIG, config_reg);
}
 
/****************************************************************************/
 
//Power up now. Radio will not power down unless instructed by MCU for config changes etc.
void RF24::powerUp(void)
{
    // if not powered up then power up and wait for the radio to initialize
    if (!(config_reg & _BV(nRF24L01::PWR_UP))) {
        config_reg |= _BV(nRF24L01::PWR_UP);
        write_register(nRF24L01::CONFIG, config_reg);
 
        // For nRF24L01+ to go from power down mode to TX or RX mode it must first pass through stand-by mode.
        // There must be a delay of Tpd2stby (see Table 16.) after the nRF24L01+ leaves power down mode before
        // the CEis set high. - Tpd2stby can be up to 5ms per the 1.0 datasheet
        delayMicroseconds(RF24_POWERUP_DELAY);
    }
}
 
/******************************************************************/
#if defined(FAILURE_HANDLING) || defined(RF24_LINUX)
 
void RF24::errNotify()
{
    #if defined(RF24_DEBUG) || defined(RF24_LINUX)
    printf_P(PSTR("RF24 HARDWARE FAIL: Radio not responding, verify pin connections, wiring, etc.\r\n"));
    #endif
    #if defined(FAILURE_HANDLING)
    failureDetected = 1;
    #else
    delay(5000);
    #endif
}
 
/******************************************************************/
 
int8_t RF24::errHandler(bool* doRecovery)
{
 
    //Wait until complete or failed
    uint32_t timer = millis();
 
    while (!(update() & (RF24_TX_DS | RF24_TX_DF))) {
        if (millis() - timer > 95) {
    #if defined(FAILURE_HANDLING)
            flush_rx();
            flush_tx();
            if (doRecovery) {
                *doRecovery = false;
                failureRecoveryAttempts++;
                ce(LOW);
                return -1;
            }
            else {
    #endif
                errNotify();
    #if defined(FAILURE_HANDLING)
            }
            return 0;
    #else
            delay(100);
    #endif
        }
    }
    return 0;
}
 
/******************************************************************/
 
void RF24::errHandler()
{
 
    #if defined(FAILURE_HANDLING)
    flush_tx();
    flush_rx();
    if (!failureFlushed) {
        failureFlushed = true;
        failureRecoveryAttempts++;
    }
    else {
    #endif
        errNotify();
    #if defined(FAILURE_HANDLING)
        failureFlushed = false;
    }
    ce(LOW);
    #endif
}
 
#endif
 
/******************************************************************/
 
//Similar to the previous write, clears the interrupt flags
bool RF24::write(const void* buf, uint8_t len, const bool multicast)
{
 
    //Start Writing
#if defined(FAILURE_HANDLING) || defined(RF24_LINUX)
    bool doRecovery = true;
    do {
#endif
        startFastWrite(buf, len, multicast);
#if defined(FAILURE_HANDLING) || defined(RF24_LINUX)
    } while (errHandler(&doRecovery) < 0);
#endif
 
    ce(LOW);
 
    write_register(nRF24L01::STATUS, RF24_IRQ_ALL);
 
    //Max retries exceeded
    if (status & RF24_TX_DF) {
        flush_tx(); // Only going to be 1 packet in the FIFO at a time using this method, so just flush
        return 0;
    }
    //TX OK 1 or 0
    return 1;
}
 
/****************************************************************************/
 
bool RF24::write(const void* buf, uint8_t len)
{
    return write(buf, len, 0);
}
 
/****************************************************************************/
 
//For general use, the interrupt flags are not important to clear
bool RF24::writeBlocking(const void* buf, uint8_t len, uint32_t timeout)
{
    //Block until the FIFO is NOT full.
    //Keep track of the MAX retries and set auto-retry if seeing failures
    //This way the FIFO will fill up and allow blocking until packets go through
    //The radio will auto-clear everything in the FIFO as long as CE remains high
#if defined(FAILURE_HANDLING)
    bool timeoutInvoked = false;
#endif
 
    uint32_t timer = millis(); // Get the time that the payload transmission started
 
    while (update() & _BV(nRF24L01::TX_FULL)) { // Blocking only if FIFO is full. This will loop and block until TX is successful or timeout
 
        if (status & RF24_TX_DF) { // If MAX Retries have been reached
            reUseTX();             // Set re-transmit and clear the MAX_RT interrupt flag
            if (millis() - timer > timeout) {
#if defined(FAILURE_HANDLING)
                failureFlushed = false;
#endif
                return 0; // If this payload has exceeded the user-defined timeout, exit and return 0
            }
        }
#if defined(FAILURE_HANDLING) || defined(RF24_LINUX)
        if (millis() - timer > (timeout + 95)) {
            errHandler();
    #if defined(FAILURE_HANDLING)
            timeoutInvoked = true;
            if (!failureFlushed) {
    #endif
                return 0;
    #if defined(FAILURE_HANDLING)
            }
    #endif
        }
#endif
    }
 
    //Start Writing
    startFastWrite(buf, len, 0); // Write the payload if a buffer is clear
#if defined(FAILURE_HANDLING)
    if (!timeoutInvoked) {
        failureFlushed = false;
    }
#endif
    return 1; // Return 1 to indicate successful transmission
}
 
/****************************************************************************/
 
void RF24::reUseTX()
{
    ce(LOW);
    write_register(nRF24L01::STATUS, RF24_TX_DF); //Clear max retry flag
    read_register(nRF24L01::REUSE_TX_PL, (uint8_t*)nullptr, 0);
    IF_RF24_DEBUG(printf_P("[Reusing payload in TX FIFO]"););
    ce(HIGH); //Re-Transfer packet
}
 
/****************************************************************************/
 
bool RF24::writeFast(const void* buf, uint8_t len, const bool multicast)
{
    //Block until the FIFO is NOT full.
    //Keep track of the MAX retries and set auto-retry if seeing failures
    //Return 0 so the user can control the retries and set a timer or failure counter if required
    //The radio will auto-clear everything in the FIFO as long as CE remains high
 
#if defined(FAILURE_HANDLING) || defined(RF24_LINUX)
    uint32_t timer = millis();
    bool timeoutInvoked = false;
#endif
 
    //Blocking only if FIFO is full. This will loop and block until TX is successful or fail
    while (update() & _BV(nRF24L01::TX_FULL)) {
        if (status & RF24_TX_DF) {
#if defined(FAILURE_HANDLING)
            failureFlushed = false;
#endif
            return 0; //Return 0. The previous payload has not been retransmitted
            // From the user perspective, if you get a 0, call txStandBy()
        }
#if defined(FAILURE_HANDLING) || defined(RF24_LINUX)
        if (millis() - timer > 95) {
            timeoutInvoked = true;
            errHandler();
    #if defined(FAILURE_HANDLING)
            if (!failureFlushed) {
    #endif
                return 0;
    #if defined(FAILURE_HANDLING)
            }
    #endif
        }
#endif
    }
    startFastWrite(buf, len, multicast); // Start Writing
#if defined(FAILURE_HANDLING)
    if (!timeoutInvoked) {
        failureFlushed = false;
    }
#endif
    return 1;
}
 
bool RF24::writeFast(const void* buf, uint8_t len)
{
    return writeFast(buf, len, 0);
}
 
/****************************************************************************/
 
//Per the documentation, we want to set PTX Mode when not listening. Then all we do is write data and set CE high
//In this mode, if we can keep the FIFO buffers loaded, packets will transmit immediately (no 130us delay)
//Otherwise we enter Standby-II mode, which is still faster than standby mode
//Also, we remove the need to keep writing the config register over and over and delaying for 150 us each time if sending a stream of data
 
void RF24::startFastWrite(const void* buf, uint8_t len, const bool multicast, bool startTx)
{ //TMRh20
 
    write_payload(buf, len, multicast ? nRF24L01::W_TX_PAYLOAD_NO_ACK : nRF24L01::W_TX_PAYLOAD);
    if (startTx) {
        ce(HIGH);
    }
}
 
/****************************************************************************/
 
//Added the original startWrite back in so users can still use interrupts, ack payloads, etc
//Allows the library to pass all tests
bool RF24::startWrite(const void* buf, uint8_t len, const bool multicast)
{
 
    // Send the payload
    write_payload(buf, len, multicast ? nRF24L01::W_TX_PAYLOAD_NO_ACK : nRF24L01::W_TX_PAYLOAD);
    ce(HIGH);
#if !defined(F_CPU) || F_CPU > 20000000
    delayMicroseconds(10);
#endif
#ifdef ARDUINO_ARCH_STM32
    if (F_CPU > 20000000) {
        delayMicroseconds(10);
    }
#endif
    ce(LOW);
    return !(status & _BV(nRF24L01::TX_FULL));
}
 
/****************************************************************************/
 
bool RF24::rxFifoFull()
{
    return read_register(nRF24L01::FIFO_STATUS) & _BV(nRF24L01::RX_FULL);
}
 
/****************************************************************************/
 
rf24_fifo_state_e RF24::isFifo(bool about_tx)
{
    uint8_t state = (read_register(nRF24L01::FIFO_STATUS) >> (4 * about_tx)) & 3;
    return static_cast<rf24_fifo_state_e>(state);
}
 
/****************************************************************************/
 
bool RF24::isFifo(bool about_tx, bool check_empty)
{
    return static_cast<bool>(static_cast<uint8_t>(isFifo(about_tx)) & _BV(!check_empty));
}
 
/****************************************************************************/
 
bool RF24::txStandBy()
{
 
#if defined(FAILURE_HANDLING) || defined(RF24_LINUX)
    uint32_t timeout = millis();
#endif
    while (!(read_register(nRF24L01::FIFO_STATUS) & _BV(nRF24L01::TX_EMPTY))) {
        if (status & RF24_TX_DF) {
            write_register(nRF24L01::STATUS, RF24_TX_DF);
            ce(LOW);
            flush_tx(); //Non blocking, flush the data
#if defined(FAILURE_HANDLING)
            failureFlushed = false;
#endif
            return 0;
        }
#if defined(FAILURE_HANDLING) || defined(RF24_LINUX)
        if (millis() - timeout > 95) {
            errHandler();
            return 0;
        }
#endif
    }
 
    ce(LOW); //Set STANDBY-I mode
#if defined(FAILURE_HANDLING)
    failureFlushed = false;
#endif
    return 1;
}
 
/****************************************************************************/
 
bool RF24::txStandBy(uint32_t timeout, bool startTx)
{
 
    if (startTx) {
        stopListening();
        ce(HIGH);
    }
    uint32_t start = millis();
 
    while (!(read_register(nRF24L01::FIFO_STATUS) & _BV(nRF24L01::TX_EMPTY))) {
        if (status & RF24_TX_DF) {
            write_register(nRF24L01::STATUS, RF24_TX_DF);
            ce(LOW); // Set re-transmit
            ce(HIGH);
            if (millis() - start >= timeout) {
                ce(LOW);
                flush_tx();
#if defined(FAILURE_HANDLING)
                failureFlushed = false;
#endif
                return 0;
            }
        }
#if defined(FAILURE_HANDLING) || defined(RF24_LINUX)
        if (millis() - start > timeout + 95) {
            errHandler();
            return 0;
        }
#endif
    }
 
    ce(LOW); //Set STANDBY-I mode
#if defined(FAILURE_HANDLING)
    failureFlushed = false;
#endif
    return 1;
}
 
/****************************************************************************/
 
void RF24::maskIRQ(bool tx, bool fail, bool rx)
{
    /* clear the interrupt flags */
    config_reg = static_cast<uint8_t>(config_reg & ~(1 << nRF24L01::MASK_MAX_RT | 1 << nRF24L01::MASK_TX_DS | 1 << nRF24L01::MASK_RX_DR));
    /* set the specified interrupt flags */
    config_reg = static_cast<uint8_t>(config_reg | fail << nRF24L01::MASK_MAX_RT | tx << nRF24L01::MASK_TX_DS | rx << nRF24L01::MASK_RX_DR);
    write_register(nRF24L01::CONFIG, config_reg);
}
 
/****************************************************************************/
 
uint8_t RF24::getDynamicPayloadSize(void)
{
    uint8_t result = read_register(nRF24L01::R_RX_PL_WID);
 
    if (result > 32 || !result) {
        flush_rx();
        return 0;
    }
    return result;
}
 
/****************************************************************************/
 
bool RF24::available(void)
{
    return (read_register(nRF24L01::FIFO_STATUS) & 1) == 0;
}
 
/****************************************************************************/
 
bool RF24::available(uint8_t* pipe_num)
{
    if (available()) { // if RX FIFO is not empty
        *pipe_num = (update() >> nRF24L01::RX_P_NO) & 0x07;
        return 1;
    }
    return 0;
}
 
/****************************************************************************/
 
void RF24::read(void* buf, uint8_t len)
{
 
    // Fetch the payload
    read_payload(buf, len);
 
    //Clear the only applicable interrupt flags
    write_register(nRF24L01::STATUS, RF24_RX_DR);
}
 
/****************************************************************************/
 
void RF24::whatHappened(bool& tx_ok, bool& tx_fail, bool& rx_ready)
{
    // Read the status & reset the status in one easy call
    // Or is that such a good idea?
    write_register(nRF24L01::STATUS, RF24_IRQ_ALL);
 
    // Report to the user what happened
    tx_ok = status & RF24_TX_DS;
    tx_fail = status & RF24_TX_DF;
    rx_ready = status & RF24_RX_DR;
}
 
/****************************************************************************/
 
uint8_t RF24::clearStatusFlags(uint8_t flags)
{
    write_register(nRF24L01::STATUS, flags & RF24_IRQ_ALL);
    return status;
}
 
/****************************************************************************/
 
void RF24::setStatusFlags(uint8_t flags)
{
    // flip the `flags` to translate from "human understanding"
    config_reg = (config_reg & ~RF24_IRQ_ALL) | (~flags & RF24_IRQ_ALL);
    write_register(nRF24L01::CONFIG, config_reg);
}
 
/****************************************************************************/
 
uint8_t RF24::getStatusFlags()
{
    return status;
}
 
/****************************************************************************/
 
uint8_t RF24::update()
{
    read_register(nRF24L01::NOP, (uint8_t*)nullptr, 0);
    return status;
}
 
/****************************************************************************/
 
void RF24::openWritingPipe(uint64_t value)
{
    // Note that AVR 8-bit uC's store this LSB first, and the NRF24L01(+)
    // expects it LSB first too, so we're good.
 
    write_register(nRF24L01::RX_ADDR_P0, reinterpret_cast<uint8_t*>(&value), addr_width);
    write_register(nRF24L01::TX_ADDR, reinterpret_cast<uint8_t*>(&value), addr_width);
    memcpy(pipe0_writing_address, &value, addr_width);
}
 
/****************************************************************************/
 
void RF24::openWritingPipe(const uint8_t* address)
{
    // Note that AVR 8-bit uC's store this LSB first, and the NRF24L01(+)
    // expects it LSB first too, so we're good.
    write_register(nRF24L01::RX_ADDR_P0, address, addr_width);
    write_register(nRF24L01::TX_ADDR, address, addr_width);
    memcpy(pipe0_writing_address, address, addr_width);
}
 
/****************************************************************************/
 
static const PROGMEM uint8_t child_pipe[] = {nRF24L01::RX_ADDR_P0, nRF24L01::RX_ADDR_P1, nRF24L01::RX_ADDR_P2,
                                             nRF24L01::RX_ADDR_P3, nRF24L01::RX_ADDR_P4, nRF24L01::RX_ADDR_P5};
 
void RF24::openReadingPipe(uint8_t child, uint64_t address)
{
    // If this is pipe 0, cache the address.  This is needed because
    // openWritingPipe() will overwrite the pipe 0 address, so
    // startListening() will have to restore it.
    if (child == 0) {
        memcpy(pipe0_reading_address, &address, addr_width);
        _is_p0_rx = true;
    }
 
    if (child <= 5) {
        // For pipes 2-5, only write the LSB
        if (child > 1) {
            write_register(pgm_read_byte(&child_pipe[child]), reinterpret_cast<const uint8_t*>(&address), 1);
        }
        // avoid overwriting the TX address on pipe 0 while still in TX mode.
        // NOTE, the cached RX address on pipe 0 is written when startListening() is called.
        else if (static_cast<bool>(config_reg & _BV(nRF24L01::PRIM_RX)) || child != 0) {
            write_register(pgm_read_byte(&child_pipe[child]), reinterpret_cast<const uint8_t*>(&address), addr_width);
        }
 
        // Note it would be more efficient to set all of the bits for all open
        // pipes at once.  However, I thought it would make the calling code
        // more simple to do it this way.
        write_register(nRF24L01::EN_RXADDR, static_cast<uint8_t>(read_register(nRF24L01::EN_RXADDR) | _BV(pgm_read_byte(&child_pipe_enable[child]))));
    }
}
 
/****************************************************************************/
 
void RF24::setAddressWidth(uint8_t a_width)
{
    a_width = static_cast<uint8_t>(a_width - 2);
    if (a_width) {
        write_register(nRF24L01::SETUP_AW, static_cast<uint8_t>(a_width % 4));
        addr_width = static_cast<uint8_t>((a_width % 4) + 2);
    }
    else {
        write_register(nRF24L01::SETUP_AW, static_cast<uint8_t>(0));
        addr_width = static_cast<uint8_t>(2);
    }
}
 
/****************************************************************************/
 
void RF24::openReadingPipe(uint8_t child, const uint8_t* address)
{
    // If this is pipe 0, cache the address.  This is needed because
    // openWritingPipe() will overwrite the pipe 0 address, so
    // startListening() will have to restore it.
    if (child == 0) {
        memcpy(pipe0_reading_address, address, addr_width);
        _is_p0_rx = true;
    }
    if (child <= 5) {
        // For pipes 2-5, only write the LSB
        if (child > 1) {
            write_register(pgm_read_byte(&child_pipe[child]), address, 1);
        }
        // avoid overwriting the TX address on pipe 0 while still in TX mode.
        // NOTE, the cached RX address on pipe 0 is written when startListening() is called.
        else if (static_cast<bool>(config_reg & _BV(nRF24L01::PRIM_RX)) || child != 0) {
            write_register(pgm_read_byte(&child_pipe[child]), address, addr_width);
        }
 
        // Note it would be more efficient to set all of the bits for all open
        // pipes at once.  However, I thought it would make the calling code
        // more simple to do it this way.
        write_register(nRF24L01::EN_RXADDR, static_cast<uint8_t>(read_register(nRF24L01::EN_RXADDR) | _BV(pgm_read_byte(&child_pipe_enable[child]))));
    }
}
 
/****************************************************************************/
 
void RF24::closeReadingPipe(uint8_t pipe)
{
    write_register(nRF24L01::EN_RXADDR, static_cast<uint8_t>(read_register(nRF24L01::EN_RXADDR) & ~_BV(pgm_read_byte(&child_pipe_enable[pipe]))));
    if (!pipe) {
        // keep track of pipe 0's RX state to avoid null vs 0 in addr cache
        _is_p0_rx = false;
    }
}
 
/****************************************************************************/
 
void RF24::toggle_features(void)
{
    beginTransaction();
#if defined(RF24_SPI_PTR)
    status = _spi->transfer(nRF24L01::ACTIVATE);
    _spi->transfer(0x73);
#else
    status = _SPI.transfer(nRF24L01::ACTIVATE);
    _SPI.transfer(0x73);
#endif
    endTransaction();
}
 
/****************************************************************************/
 
void RF24::enableDynamicPayloads(void)
{
    // Enable dynamic payload throughout the system
 
    //toggle_features();
    write_register(nRF24L01::FEATURE, read_register(nRF24L01::FEATURE) | _BV(nRF24L01::EN_DPL));
 
    IF_RF24_DEBUG(printf_P("FEATURE=%i\r\n", read_register(nRF24L01::FEATURE)));
 
    // Enable dynamic payload on all pipes
    //
    // Not sure the use case of only having dynamic payload on certain
    // pipes, so the library does not support it.
    write_register(nRF24L01::DYNPD, read_register(nRF24L01::DYNPD) | _BV(nRF24L01::DPL_P5) | _BV(nRF24L01::DPL_P4) | _BV(nRF24L01::DPL_P3) | _BV(nRF24L01::DPL_P2) | _BV(nRF24L01::DPL_P1) | _BV(nRF24L01::DPL_P0));
 
    dynamic_payloads_enabled = true;
}
 
/****************************************************************************/
 
void RF24::disableDynamicPayloads(void)
{
    // Disables dynamic payload throughout the system.  Also disables Ack Payloads
 
    //toggle_features();
    write_register(nRF24L01::FEATURE, 0);
 
    IF_RF24_DEBUG(printf_P("FEATURE=%i\r\n", read_register(nRF24L01::FEATURE)));
 
    // Disable dynamic payload on all pipes
    //
    // Not sure the use case of only having dynamic payload on certain
    // pipes, so the library does not support it.
    write_register(nRF24L01::DYNPD, 0);
 
    dynamic_payloads_enabled = false;
    ack_payloads_enabled = false;
}
 
/****************************************************************************/
 
void RF24::enableAckPayload(void)
{
    // enable ack payloads and dynamic payload features
 
    if (!ack_payloads_enabled) {
        write_register(nRF24L01::FEATURE, read_register(nRF24L01::FEATURE) | _BV(nRF24L01::EN_ACK_PAY) | _BV(nRF24L01::EN_DPL));
 
        IF_RF24_DEBUG(printf_P("FEATURE=%i\r\n", read_register(nRF24L01::FEATURE)));
 
        // Enable dynamic payload on pipes 0 & 1
        write_register(nRF24L01::DYNPD, read_register(nRF24L01::DYNPD) | _BV(nRF24L01::DPL_P1) | _BV(nRF24L01::DPL_P0));
        dynamic_payloads_enabled = true;
        ack_payloads_enabled = true;
    }
}
 
/****************************************************************************/
 
void RF24::disableAckPayload(void)
{
    // disable ack payloads (leave dynamic payload features as is)
    if (ack_payloads_enabled) {
        write_register(nRF24L01::FEATURE, static_cast<uint8_t>(read_register(nRF24L01::FEATURE) & ~_BV(nRF24L01::EN_ACK_PAY)));
 
        IF_RF24_DEBUG(printf_P("FEATURE=%i\r\n", read_register(nRF24L01::FEATURE)));
 
        ack_payloads_enabled = false;
    }
}
 
/****************************************************************************/
 
void RF24::enableDynamicAck(void)
{
    //
    // enable dynamic ack features
    //
    //toggle_features();
    write_register(nRF24L01::FEATURE, read_register(nRF24L01::FEATURE) | _BV(nRF24L01::EN_DYN_ACK));
 
    IF_RF24_DEBUG(printf_P("FEATURE=%i\r\n", read_register(nRF24L01::FEATURE)));
}
 
/****************************************************************************/
 
bool RF24::writeAckPayload(uint8_t pipe, const void* buf, uint8_t len)
{
    if (ack_payloads_enabled) {
        const uint8_t* current = reinterpret_cast<const uint8_t*>(buf);
 
        write_register(nRF24L01::W_ACK_PAYLOAD | (pipe & 0x07), current, rf24_min(len, static_cast<uint8_t>(32)));
        return !(status & _BV(nRF24L01::TX_FULL));
    }
    return 0;
}
 
/****************************************************************************/
 
bool RF24::isAckPayloadAvailable(void)
{
    return available();
}
 
/****************************************************************************/
 
bool RF24::isPVariant(void)
{
    return _is_p_variant;
}
 
/****************************************************************************/
 
void RF24::setAutoAck(bool enable)
{
    if (enable) {
        write_register(nRF24L01::EN_AA, 0x3F);
    }
    else {
        write_register(nRF24L01::EN_AA, 0);
        // accommodate ACK payloads feature
        if (ack_payloads_enabled) {
            disableAckPayload();
        }
    }
}
 
/****************************************************************************/
 
void RF24::setAutoAck(uint8_t pipe, bool enable)
{
    if (pipe < 6) {
        uint8_t en_aa = read_register(nRF24L01::EN_AA);
        if (enable) {
            en_aa |= static_cast<uint8_t>(_BV(pipe));
        }
        else {
            en_aa = static_cast<uint8_t>(en_aa & ~_BV(pipe));
            if (ack_payloads_enabled && !pipe) {
                disableAckPayload();
            }
        }
        write_register(nRF24L01::EN_AA, en_aa);
    }
}
 
/****************************************************************************/
 
bool RF24::testCarrier(void)
{
    return (read_register(nRF24L01::CD) & 1);
}
 
/****************************************************************************/
 
bool RF24::testRPD(void)
{
    return (read_register(nRF24L01::RPD) & 1);
}
 
/****************************************************************************/
 
void RF24::setPALevel(uint8_t level, bool lnaEnable)
{
    uint8_t setup = read_register(nRF24L01::RF_SETUP) & static_cast<uint8_t>(0xF8);
    setup |= _pa_level_reg_value(level, lnaEnable);
    write_register(nRF24L01::RF_SETUP, setup);
}
 
/****************************************************************************/
 
uint8_t RF24::getPALevel(void)
{
    return (read_register(nRF24L01::RF_SETUP) & (_BV(nRF24L01::RF_PWR_LOW) | _BV(nRF24L01::RF_PWR_HIGH))) >> 1;
}
 
/****************************************************************************/
 
uint8_t RF24::getARC(void)
{
    return read_register(nRF24L01::OBSERVE_TX) & 0x0F;
}
 
/****************************************************************************/
 
bool RF24::setDataRate(rf24_datarate_e speed)
{
    bool result = false;
    uint8_t setup = read_register(nRF24L01::RF_SETUP);
 
    // HIGH and LOW '00' is 1Mbs - our default
    setup = static_cast<uint8_t>(setup & ~(_BV(nRF24L01::RF_DR_LOW) | _BV(nRF24L01::RF_DR_HIGH)));
    setup |= _data_rate_reg_value(speed);
 
    write_register(nRF24L01::RF_SETUP, setup);
 
    // Verify our result
    if (read_register(nRF24L01::RF_SETUP) == setup) {
        result = true;
    }
    return result;
}
 
/****************************************************************************/
 
rf24_datarate_e RF24::getDataRate(void)
{
    rf24_datarate_e result;
    uint8_t dr = read_register(nRF24L01::RF_SETUP) & (_BV(nRF24L01::RF_DR_LOW) | _BV(nRF24L01::RF_DR_HIGH));
 
    // switch uses RAM (evil!)
    // Order matters in our case below
    if (dr == _BV(nRF24L01::RF_DR_LOW)) {
        // '10' = 250KBPS
        result = RF24_250KBPS;
    }
    else if (dr == _BV(nRF24L01::RF_DR_HIGH)) {
        // '01' = 2MBPS
        result = RF24_2MBPS;
    }
    else {
        // '00' = 1MBPS
        result = RF24_1MBPS;
    }
    return result;
}
 
/****************************************************************************/
 
void RF24::setCRCLength(rf24_crclength_e length)
{
    config_reg = static_cast<uint8_t>(config_reg & ~(_BV(nRF24L01::CRCO) | _BV(nRF24L01::EN_CRC)));
 
    // switch uses RAM (evil!)
    if (length == RF24_CRC_DISABLED) {
        // Do nothing, we turned it off above.
    }
    else if (length == RF24_CRC_8) {
        config_reg |= _BV(nRF24L01::EN_CRC);
    }
    else {
        config_reg |= _BV(nRF24L01::EN_CRC);
        config_reg |= _BV(nRF24L01::CRCO);
    }
    write_register(nRF24L01::CONFIG, config_reg);
}
 
/****************************************************************************/
 
rf24_crclength_e RF24::getCRCLength(void)
{
    rf24_crclength_e result = RF24_CRC_DISABLED;
    uint8_t AA = read_register(nRF24L01::EN_AA);
    config_reg = read_register(nRF24L01::CONFIG);
 
    if (config_reg & _BV(nRF24L01::EN_CRC) || AA) {
        if (config_reg & _BV(nRF24L01::CRCO)) {
            result = RF24_CRC_16;
        }
        else {
            result = RF24_CRC_8;
        }
    }
 
    return result;
}
 
/****************************************************************************/
 
void RF24::disableCRC(void)
{
    config_reg = static_cast<uint8_t>(config_reg & ~_BV(nRF24L01::EN_CRC));
    write_register(nRF24L01::CONFIG, config_reg);
}
 
/****************************************************************************/
void RF24::setRetries(uint8_t delay, uint8_t count)
{
    write_register(nRF24L01::SETUP_RETR, static_cast<uint8_t>(rf24_min(15, delay) << nRF24L01::ARD | rf24_min(15, count)));
}
 
/****************************************************************************/
void RF24::startConstCarrier(rf24_pa_dbm_e level, uint8_t channel)
{
    stopListening();
    write_register(nRF24L01::RF_SETUP, read_register(nRF24L01::RF_SETUP) | _BV(nRF24L01::CONT_WAVE) | _BV(nRF24L01::PLL_LOCK));
    if (isPVariant()) {
        setAutoAck(0);
        setRetries(0, 0);
        uint8_t dummy_buf[32];
        for (uint8_t i = 0; i < 32; ++i)
            dummy_buf[i] = 0xFF;
 
        // use write_register() instead of openWritingPipe() to bypass
        // truncation of the address with the current RF24::addr_width value
        write_register(nRF24L01::TX_ADDR, reinterpret_cast<uint8_t*>(&dummy_buf), 5);
        flush_tx(); // so we can write to top level
 
        // use write_register() instead of write_payload() to bypass
        // truncation of the payload with the current RF24::payload_size value
        write_register(nRF24L01::W_TX_PAYLOAD, reinterpret_cast<const uint8_t*>(&dummy_buf), 32);
 
        disableCRC();
    }
    setPALevel(level);
    setChannel(channel);
    IF_RF24_DEBUG(printf_P(PSTR("RF_SETUP=%02x\r\n"), read_register(nRF24L01::RF_SETUP)));
    ce(HIGH);
    if (isPVariant()) {
        delay(1);  // datasheet says 1 ms is ok in this instance
        reUseTX(); // CE gets toggled here
    }
}
 
/****************************************************************************/
 
void RF24::stopConstCarrier()
{
    /*
     * A note from the datasheet:
     * Do not use REUSE_TX_PL together with CONT_WAVE=1. When both these
     * registers are set the chip does not react when setting CE low. If
     * however, both registers are set PWR_UP = 0 will turn TX mode off.
     */
    powerDown(); // per datasheet recommendation (just to be safe)
    write_register(nRF24L01::RF_SETUP, static_cast<uint8_t>(read_register(nRF24L01::RF_SETUP) & ~_BV(nRF24L01::CONT_WAVE) & ~_BV(nRF24L01::PLL_LOCK)));
    ce(LOW);
    flush_tx();
    if (isPVariant()) {
        // restore the cached TX address
        write_register(nRF24L01::TX_ADDR, pipe0_writing_address, addr_width);
    }
}
 
/****************************************************************************/
 
void RF24::toggleAllPipes(bool isEnabled)
{
    write_register(nRF24L01::EN_RXADDR, static_cast<uint8_t>(isEnabled ? 0x3F : 0));
}
 
/****************************************************************************/
 
uint8_t RF24::_data_rate_reg_value(rf24_datarate_e speed)
{
#if !defined(F_CPU) || F_CPU > 20000000
    txDelay = 280;
#else //16Mhz Arduino
    txDelay = 85;
#endif
    if (speed == RF24_250KBPS) {
#if !defined(F_CPU) || F_CPU > 20000000
        txDelay = 505;
#else //16Mhz Arduino
        txDelay = 155;
#endif
        // Must set the RF_DR_LOW to 1; RF_DR_HIGH (used to be RF_DR) is already 0
        // Making it '10'.
        return static_cast<uint8_t>(_BV(nRF24L01::RF_DR_LOW));
    }
    else if (speed == RF24_2MBPS) {
#if !defined(F_CPU) || F_CPU > 20000000
        txDelay = 240;
#else // 16Mhz Arduino
        txDelay = 65;
#endif
        // Set 2Mbs, RF_DR (RF_DR_HIGH) is set 1
        // Making it '01'
        return static_cast<uint8_t>(_BV(nRF24L01::RF_DR_HIGH));
    }
    // HIGH and LOW '00' is 1Mbs - our default
    return static_cast<uint8_t>(0);
}
 
/****************************************************************************/
 
uint8_t RF24::_pa_level_reg_value(uint8_t level, bool lnaEnable)
{
    // If invalid level, go to max PA
    // Else set level as requested
    // + lnaEnable (1 or 0) to support the SI24R1 chip extra bit
    return static_cast<uint8_t>(((level > RF24_PA_MAX ? static_cast<uint8_t>(RF24_PA_MAX) : level) << 1) + lnaEnable);
}
 
/****************************************************************************/
 
void RF24::setRadiation(uint8_t level, rf24_datarate_e speed, bool lnaEnable)
{
    uint8_t setup = _data_rate_reg_value(speed);
    setup |= _pa_level_reg_value(level, lnaEnable);
    write_register(nRF24L01::RF_SETUP, setup);
}