File content as of revision 1:d061e50ccc5d:

/*
 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 "nRF24L01P_Maniacbug.h"

/****************************************************************************/

void RF24::csn(int mode)
{
//    // 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
////#ifdef ARDUINO
////  spi.setBitOrder(MSBFIRST);
////  spi.setDataMode(SPI_MODE0);
////  spi.setClockDivider(SPI_CLOCK_DIV4);
////#endif
////  digitalWrite(csn_pin,mode);
//
//
    csn_pin = mode;
}

/****************************************************************************/

void RF24::ce(int level)
{
    //digitalWrite(ce_pin,level);
    ce_pin = level;
    wait_us(_NRF24L01P_TIMING_Tpece2csn_us);
}

/****************************************************************************/

uint8_t RF24::read_register(uint8_t reg, uint8_t* buf, uint8_t len)
{
    uint8_t status;

    csn(LOW);
    status = spi.write( R_REGISTER | ( REGISTER_MASK & reg ) );
    while ( len-- )
        *buf++ = spi.write(0xff);

    csn(HIGH);

    return status;
}

/****************************************************************************/

uint8_t RF24::read_register(uint8_t reg)    //checked
{
    csn(LOW);
    spi.write( R_REGISTER | ( REGISTER_MASK & reg ) );
    uint8_t result = spi.write(0xff);

    csn(HIGH);
    return result;
}

/****************************************************************************/

uint8_t RF24::write_register(uint8_t reg, const uint8_t* buf, uint8_t len)
{
    uint8_t status;
    int originalCe = ce_pin;
    ce(LOW);

    csn(LOW);
    status = spi.write( W_REGISTER | ( REGISTER_MASK & reg ) );
    while ( len-- )
        spi.write(*buf++);

    csn(HIGH);
    
    ce_pin = originalCe;
    wait_us( _NRF24L01P_TIMING_Tpece2csn_us );

    return status;
}

/****************************************************************************/

uint8_t RF24::write_register(uint8_t reg, uint8_t value)        //checked
{
    uint8_t status;

//    IF_SERIAL_DEBUG(printf(PSTR("write_register(%02x,%02x)\r\n"),reg,value));
    int originalCe = ce_pin;
    ce(LOW);


    csn(LOW);
    status = spi.write( W_REGISTER | ( REGISTER_MASK & reg ) );
    spi.write(value);
    csn(HIGH);

    ce_pin = originalCe;
    wait_us( _NRF24L01P_TIMING_Tpece2csn_us );

    return status;
}

/****************************************************************************/

uint8_t RF24::write_payload(const void* buf, uint8_t len)
{
    uint8_t status;

    const uint8_t* current = reinterpret_cast<const uint8_t*>(buf);

    uint8_t data_len = min(len,payload_size);
    uint8_t blank_len = dynamic_payloads_enabled ? 0 : payload_size - data_len;

    //printf("[Writing %u bytes %u blanks]",data_len,blank_len);

    csn(LOW);
    status = spi.write( W_TX_PAYLOAD );
    while ( data_len-- )
        spi.write(*current++);
    while ( blank_len-- )
        spi.write(0);
    csn(HIGH);

    return status;
}

/****************************************************************************/

uint8_t RF24::read_payload(void* buf, uint8_t len)
{
    uint8_t status;
    uint8_t* current = reinterpret_cast<uint8_t*>(buf);

    uint8_t data_len = min(len,payload_size);
    uint8_t blank_len = dynamic_payloads_enabled ? 0 : payload_size - data_len;

    //printf("[Reading %u bytes %u blanks]",data_len,blank_len);

    csn(LOW);
    status = spi.write( R_RX_PAYLOAD );
    while ( data_len-- )
        *current++ = spi.write(0xff);
    while ( blank_len-- )
        spi.write(0xff);
    csn(HIGH);

    return status;
}

/****************************************************************************/

uint8_t RF24::flush_rx(void)
{
    uint8_t status;

    csn(LOW);
    status = spi.write( FLUSH_RX );
    csn(HIGH);

    return status;
}

/****************************************************************************/

uint8_t RF24::flush_tx(void)
{
    uint8_t status;

    csn(LOW);
    status = spi.write( FLUSH_TX );
    csn(HIGH);

    return status;
}

/****************************************************************************/

uint8_t RF24::get_status(void)
{
    uint8_t status;

    csn(LOW);
    status = spi.write( NOP );
    csn(HIGH);

    return status;
}

/****************************************************************************/

void RF24::print_status(uint8_t status)
{
    printf("STATUS = 0x%02x RX_DR=%x TX_DS=%x MAX_RT=%x RX_P_NO=%x TX_FULL=%x\r\n",
           status,
           (status & RX_DR)?1:0,
           (status & TX_DS)?1:0,
           (status & MAX_RT)?1:0,
           ((status >> RX_P_NO) & 7),
           (status & TX_FULL)?1:0
          );
}

///****************************************************************************/

void RF24::print_observe_tx(uint8_t value)
{
    printf("OBSERVE_TX=%02x: POLS_CNT=%x ARC_CNT=%x\r\n",
           value,
           (value >> PLOS_CNT) & 15,
           (value >> ARC_CNT) & 15
          );
}

/****************************************************************************/

void RF24::print_byte_register(const char* name, uint8_t reg, uint8_t qty)
{
//    char extra_tab = strlen(name) < 8 ? '\t' : 0;
    printf("%s =",name);
    while (qty--)
        printf(" 0x%02x",read_register(reg++));
    printf("\r\n");
}

/****************************************************************************/

void RF24::print_address_register(const char* name, uint8_t reg, uint8_t qty)
{
//    char extra_tab = strlen(name) < 8 ? '\t' : 0;
    printf("%s =",name);

    while (qty--) {
        uint8_t buffer[5];
        read_register(reg++,buffer,sizeof buffer);

        printf(" 0x");
        uint8_t* bufptr = buffer + sizeof buffer;
        while( --bufptr >= buffer )
            printf("%02x",*bufptr);
    }

    printf("\r\n");
}

/****************************************************************************/

RF24::RF24(PinName mosi, PinName miso, PinName sck, PinName _cspin, PinName _cepin):
    ce_pin(_cepin), csn_pin(_cspin), wide_band(true), p_variant(false),
    payload_size(32), ack_payload_available(false), dynamic_payloads_enabled(false),
    pipe0_reading_address(0), spi(mosi, miso, sck)
{
}

/****************************************************************************/

void RF24::setChannel(uint8_t channel)
{
    // TODO: This method could take advantage of the 'wide_band' calculation
    // done in setChannel() to require certain channel spacing.

    const uint8_t max_channel = 127;
    write_register(RF_CH,min(channel,max_channel));
}

/****************************************************************************/

void RF24::setPayloadSize(uint8_t size)
{
    const uint8_t max_payload_size = 32;
    payload_size = min(size,max_payload_size);
}

/****************************************************************************/

uint8_t RF24::getPayloadSize(void)
{
    return payload_size;
}

/****************************************************************************/

static const char rf24_datarate_e_str_0[]  = "1MBPS";
static const char rf24_datarate_e_str_1[]  = "2MBPS";
static const char rf24_datarate_e_str_2[]  = "250KBPS";
static const char * const rf24_datarate_e_str_P[]  = {
    rf24_datarate_e_str_0,
    rf24_datarate_e_str_1,
    rf24_datarate_e_str_2,
};
static const char rf24_model_e_str_0[]  = "nRF24L01";
static const char rf24_model_e_str_1[]  = "nRF24L01+";
static const char * const rf24_model_e_str_P[]  = {
    rf24_model_e_str_0,
    rf24_model_e_str_1,
};
static const char rf24_crclength_e_str_0[]  = "Disabled";
static const char rf24_crclength_e_str_1[]  = "8 bits";
static const char rf24_crclength_e_str_2[]  = "16 bits" ;
static const char * const rf24_crclength_e_str_P[]  = {
    rf24_crclength_e_str_0,
    rf24_crclength_e_str_1,
    rf24_crclength_e_str_2,
};
static const char rf24_pa_dbm_e_str_0[]  = "PA_MIN";
static const char rf24_pa_dbm_e_str_1[]  = "PA_LOW";
static const char rf24_pa_dbm_e_str_2[]  = "PA_MED";
static const char rf24_pa_dbm_e_str_3[]  = "PA_HIGH";
static const 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,
};

void RF24::printDetails(void)
{
    print_status(get_status());

    print_address_register("RX_ADDR_P0-1",RX_ADDR_P0,2);
    print_byte_register("RX_ADDR_P2-5", RX_ADDR_P2,4);
    print_address_register("TX_ADDR",   TX_ADDR);

    print_byte_register("RX_PW_P0-6",   RX_PW_P0,6);
    print_byte_register("EN_AA",        EN_AA);
    print_byte_register("EN_RXADDR",    EN_RXADDR);
    print_byte_register("RF_CH",        RF_CH);
    print_byte_register("RF_SETUP",     RF_SETUP);
    print_byte_register("CONFIG",       CONFIG);
    print_byte_register("DYNPD/FEATURE",DYNPD,2);

    printf("Data Rate\t = %s\r\n",  rf24_datarate_e_str_P[getDataRate()]);
    printf("Model\t\t = %s\r\n",    rf24_model_e_str_P[isPVariant()]);
    printf("CRC Length\t = %s\r\n", rf24_crclength_e_str_P[getCRCLength()]);
    printf("PA Power\t = %s\r\n",   rf24_pa_dbm_e_str_P[getPALevel()]);
}

/****************************************************************************/

void RF24::begin(void)
{
    // Initialize pins
//    pinMode(ce_pin,OUTPUT);   //ARD
//    pinMode(csn_pin,OUTPUT);

    mainTimer.start();


    spi.frequency(_NRF24L01P_SPI_MAX_DATA_RATE/5);     // 2Mbit, 1/5th the maximum transfer rate for the SPI bus
    spi.format(8,0);                                   // 8-bit, ClockPhase = 0, ClockPolarity = 0

    wait_us(_NRF24L01P_TIMING_Tundef2pd_us);    // Wait for Power-on reset    //MBED

    // Initialize SPI bus
//    spi.begin();      //ARD

    ce(LOW);
    csn(HIGH);

    // 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 ) ;
    wait_ms(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 documentation for a more complete explanation.
    write_register(SETUP_RETR,(4 << ARD) | (15 << ARC));

    // Restore our default PA level
    setPALevel( RF24_PA_MAX ) ;

    // Determine if this is a p or non-p RF24 module and then
    // reset our data rate back to default value. This works
    // because a non-P variant won't allow the data rate to
    // be set to 250Kbps.
    if( setDataRate( RF24_250KBPS ) ) {
        p_variant = true ;
    }

    // Then set the data rate to the slowest (and most reliable) speed supported by all
    // hardware.
    setDataRate( RF24_1MBPS ) ;

    // Initialize CRC and request 2-byte (16bit) CRC
    setCRCLength( RF24_CRC_16 ) ;

    // Disable dynamic payloads, to match dynamic_payloads_enabled setting
    write_register(DYNPD,0);

    // Reset current status
    // Notice reset and flush is the last thing we do
    write_register(STATUS,RX_DR | TX_DS | MAX_RT );

    // 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);

    // Flush buffers
    flush_rx();
    flush_tx();
}

/****************************************************************************/

void RF24::startListening(void)
{
    write_register(CONFIG, read_register(CONFIG) | PWR_UP | PRIM_RX);
    write_register(STATUS, RX_DR | TX_DS | MAX_RT );

    // Restore the pipe0 adddress, if exists
    if (pipe0_reading_address)
        write_register(RX_ADDR_P0, reinterpret_cast<const uint8_t*>(&pipe0_reading_address), 5);

    // Flush buffers
    flush_rx();
    flush_tx();

    // Go!
    ce(HIGH);;

    // wait for the radio to come up (130us actually only needed)
//    delayMicroseconds(130);
    wait_us(130);
}

/****************************************************************************/

void RF24::stopListening(void)
{
    ce(LOW);
    flush_tx();
    flush_rx();
}

/****************************************************************************/

void RF24::powerDown(void)
{
    write_register(CONFIG,read_register(CONFIG) & ~PWR_UP);
}

/****************************************************************************/

void RF24::powerUp(void)
{
    write_register(CONFIG,read_register(CONFIG) | PWR_UP);
}

/******************************************************************/

bool RF24::write( const void* buf, uint8_t len )
{
    bool result = false;

    // Begin the write
    startWrite(buf,len);

    // ------------
    // At this point we could return from a non-blocking write, and then call
    // the rest after an interrupt

    // Instead, we are going to block here until we get TX_DS (transmission completed and ack'd)
    // or MAX_RT (maximum retries, transmission failed).  Also, we'll timeout in case the radio
    // is flaky and we get neither.

    // IN the end, the send should be blocking.  It comes back in 60ms worst case, or much faster
    // if I tighted up the retry logic.  (Default settings will be 1500us.
    // Monitor the send
    uint8_t observe_tx;
    uint8_t status;
    uint32_t sent_at = mainTimer.read_ms();
    const uint32_t timeout = 500; //ms to wait for timeout
    do {
        status = read_register(OBSERVE_TX,&observe_tx,1);
//        IF_SERIAL_DEBUG(Serial.print(observe_tx,HEX));
    } while( ! ( status & ( TX_DS | MAX_RT ) ) && ( mainTimer.read_ms() - sent_at < timeout ) );

    // The part above is what you could recreate with your own interrupt handler,
    // and then call this when you got an interrupt
    // ------------

    // Call this when you get an interrupt
    // The status tells us three things
    // * The send was successful (TX_DS)
    // * The send failed, too many retries (MAX_RT)
    // * There is an ack packet waiting (RX_DR)
    bool tx_ok, tx_fail;
    whatHappened(tx_ok,tx_fail,ack_payload_available);

    //printf("%u%u%u\r\n",tx_ok,tx_fail,ack_payload_available);

    result = tx_ok;
//    IF_SERIAL_DEBUG(Serial.print(result?"...OK.":"...Failed"));

    // Handle the ack packet
    if ( ack_payload_available ) {
        ack_payload_length = getDynamicPayloadSize();
//        IF_SERIAL_DEBUG(Serial.print("[AckPacket]/"));
//        IF_SERIAL_DEBUG(Serial.println(ack_payload_length,DEC));
    }

    // Yay, we are done.

    // Power down
    powerDown();

    // Flush buffers (Is this a relic of past experimentation, and not needed anymore?
    flush_tx();

    return result;
}
/****************************************************************************/

void RF24::startWrite( const void* buf, uint8_t len )
{
    // Transmitter power-up
    write_register(CONFIG, ( read_register(CONFIG) | PWR_UP ) & ~PRIM_RX );
    //delayMicroseconds(150);
    wait_us(150);

    // Send the payload
    write_payload( buf, len );

    // Allons!
    ce(HIGH);;
//    delayMicroseconds(15);
    wait_us(15);
    ce(LOW);
}

/****************************************************************************/

uint8_t RF24::getDynamicPayloadSize(void)
{
    uint8_t result = 0;

    csn(LOW);
    spi.write( R_RX_PL_WID );
    result = spi.write(0xff);
    csn(HIGH);

    return result;
}

/****************************************************************************/

bool RF24::available(void)
{
    return available(NULL);
}

/****************************************************************************/

bool RF24::available(uint8_t* pipe_num)
{
    uint8_t status = get_status();

    // Too noisy, enable if you really want lots o data!!
    //IF_SERIAL_DEBUG(print_status(status));

    bool result = ( status & RX_DR );

    if (result) {
        // If the caller wants the pipe number, include that
        if ( pipe_num )
            *pipe_num = ( status >> RX_P_NO ) & 7;

        // Clear the status bit

        // ??? Should this REALLY be cleared now?  Or wait until we
        // actually READ the payload?

        write_register(STATUS,RX_DR );

        // Handle ack payload receipt
        if ( status & TX_DS ) {
            write_register(STATUS,TX_DS);
        }
    }

    return result;
}

/****************************************************************************/

bool RF24::read( void* buf, uint8_t len )
{
    // Fetch the payload
    read_payload( buf, len );

    // was this the last of the data available?
    return read_register(FIFO_STATUS) & RX_EMPTY;
}

/****************************************************************************/

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?
    uint8_t status = write_register(STATUS,RX_DR | TX_DS | MAX_RT );

    // Report to the user what happened
    tx_ok = status & TX_DS;
    tx_fail = status & MAX_RT;
    rx_ready = status & RX_DR;
}

/****************************************************************************/

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(RX_ADDR_P0, reinterpret_cast<uint8_t*>(&value), 5);
    write_register(TX_ADDR, reinterpret_cast<uint8_t*>(&value), 5);

    const uint8_t max_payload_size = 32;
    write_register(RX_PW_P0,min(payload_size,max_payload_size));
}

/****************************************************************************/

static const uint8_t child_pipe[] = {
    RX_ADDR_P0, RX_ADDR_P1, RX_ADDR_P2, RX_ADDR_P3, RX_ADDR_P4, RX_ADDR_P5
};
static const uint8_t child_payload_size[] = {
    RX_PW_P0, RX_PW_P1, RX_PW_P2, RX_PW_P3, RX_PW_P4, RX_PW_P5
};
static const uint8_t child_pipe_enable[] = {
    ERX_P0, ERX_P1, ERX_P2, ERX_P3, ERX_P4, ERX_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)
        pipe0_reading_address = address;

    if (child <= 6) {
        // For pipes 2-5, only write the LSB
        if ( child < 2 )
            write_register(child_pipe[child], reinterpret_cast<const uint8_t*>(&address), 5);
        else
            write_register(child_pipe[child], reinterpret_cast<const uint8_t*>(&address), 1);

        write_register(child_payload_size[child],payload_size);

        // 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(EN_RXADDR,read_register(EN_RXADDR) | child_pipe_enable[child]);
    }
}

/****************************************************************************/

void RF24::toggle_features(void)
{
    csn(LOW);
    spi.write( ACTIVATE );
    spi.write( 0x73 );
    csn(HIGH);
}

/****************************************************************************/

void RF24::enableDynamicPayloads(void)
{
    // Enable dynamic payload throughout the system
    write_register(FEATURE,read_register(FEATURE) | EN_DPL );

    // If it didn't work, the features are not enabled
    if ( ! read_register(FEATURE) ) {
        // So enable them and try again
        toggle_features();
        write_register(FEATURE,read_register(FEATURE) | EN_DPL );
    }

//    IF_SERIAL_DEBUG(printf("FEATURE=%i\r\n",read_register(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(DYNPD,read_register(DYNPD) | DPL_P5 | DPL_P4 | DPL_P3 | DPL_P2 | DPL_P1 | DPL_P0);

    dynamic_payloads_enabled = true;
}

/****************************************************************************/

void RF24::enableAckPayload(void)
{
    //
    // enable ack payload and dynamic payload features
    //

    write_register(FEATURE,read_register(FEATURE) | EN_ACK_PAY | EN_DPL );

    // If it didn't work, the features are not enabled
    if ( ! read_register(FEATURE) ) {
        // So enable them and try again
        toggle_features();
        write_register(FEATURE,read_register(FEATURE) | EN_ACK_PAY | EN_DPL );
    }

//    IF_SERIAL_DEBUG(printf("FEATURE=%i\r\n",read_register(FEATURE)));

    //
    // Enable dynamic payload on pipes 0 & 1
    //

    write_register(DYNPD,read_register(DYNPD) | DPL_P1 | DPL_P0);
}

/****************************************************************************/

void RF24::writeAckPayload(uint8_t pipe, const void* buf, uint8_t len)
{
    const uint8_t* current = reinterpret_cast<const uint8_t*>(buf);

    csn(LOW);
    spi.write( W_ACK_PAYLOAD | ( pipe & 7 ) );
    const uint8_t max_payload_size = 32;
    uint8_t data_len = min(len,max_payload_size);
    while ( data_len-- )
        spi.write(*current++);

    csn(HIGH);
}

/****************************************************************************/

bool RF24::isAckPayloadAvailable(void)
{
    bool result = ack_payload_available;
    ack_payload_available = false;
    return result;
}

/****************************************************************************/

bool RF24::isPVariant(void)
{
    return p_variant ;
}

/****************************************************************************/

void RF24::setAutoAck(bool enable)
{
    if ( enable )
        write_register(EN_AA, 63);
    else
        write_register(EN_AA, 0);
}

/****************************************************************************/

void RF24::setAutoAck( uint8_t pipe, bool enable )
{
    if ( pipe <= 6 ) {
        uint8_t en_aa = read_register( EN_AA ) ;
        if( enable ) {
            en_aa |= pipe ;
        } else {
            en_aa &= ~pipe ;
        }
        write_register( EN_AA, en_aa ) ;
    }
}

/****************************************************************************/

bool RF24::testCarrier(void)
{
    return ( read_register(CD) & 1 );
}

/****************************************************************************/

bool RF24::testRPD(void)
{
    return ( read_register(RPD) & 1 ) ;
}

/****************************************************************************/

void RF24::setPALevel(rf24_pa_dbm_e level)
{
    uint8_t setup = read_register(RF_SETUP) ;
    setup &= ~(RF_PWR_LOW | RF_PWR_HIGH) ;

    // switch uses RAM (evil!)
    if ( level == RF24_PA_MAX ) {
        setup |= (RF_PWR_LOW | RF_PWR_HIGH) ;
    } else if ( level == RF24_PA_HIGH ) {
        setup |= RF_PWR_HIGH ;
    } else if ( level == RF24_PA_LOW ) {
        setup |= RF_PWR_LOW;
    } else if ( level == RF24_PA_MIN ) {
        // nothing
    } else if ( level == RF24_PA_ERROR ) {
        // On error, go to maximum PA
        setup |= (RF_PWR_LOW | RF_PWR_HIGH) ;
    }

    write_register( RF_SETUP, setup ) ;
}

/****************************************************************************/

rf24_pa_dbm_e RF24::getPALevel(void)
{
    rf24_pa_dbm_e result = RF24_PA_ERROR ;
    uint8_t power = read_register(RF_SETUP) & (RF_PWR_LOW | RF_PWR_HIGH) ;

    // switch uses RAM (evil!)
    if ( power == (RF_PWR_LOW | RF_PWR_HIGH) ) {
        result = RF24_PA_MAX ;
    } else if ( power == RF_PWR_HIGH) {
        result = RF24_PA_HIGH ;
    } else if ( power == RF_PWR_LOW) {
        result = RF24_PA_LOW ;
    } else {
        result = RF24_PA_MIN ;
    }

    return result ;
}

/****************************************************************************/

bool RF24::setDataRate(rf24_datarate_e speed)
{
    bool result = false;
    uint8_t setup = read_register(RF_SETUP) ;

    // HIGH and LOW '00' is 1Mbs - our default
    wide_band = false ;
    setup &= ~(RF_DR_LOW | RF_DR_HIGH) ;
    if( speed == RF24_250KBPS ) {
        // Must set the RF_DR_LOW to 1; RF_DR_HIGH (used to be RF_DR) is already 0
        // Making it '10'.
        wide_band = false ;
        setup |=  RF_DR_LOW  ;
    } else {
        // Set 2Mbs, RF_DR (RF_DR_HIGH) is set 1
        // Making it '01'
        if ( speed == RF24_2MBPS ) {
            wide_band = true ;
            setup |= RF_DR_HIGH;
        } else {
            // 1Mbs
            wide_band = false ;
        }
    }
    write_register(RF_SETUP,setup);

    // Verify our result
    if ( read_register(RF_SETUP) == setup ) {
        result = true;
    } else {
        wide_band = false;
    }

    return result;
}

/****************************************************************************/

rf24_datarate_e RF24::getDataRate( void )
{
    rf24_datarate_e result ;
    uint8_t dr = read_register(RF_SETUP) & (RF_DR_LOW | RF_DR_HIGH);

    // switch uses RAM (evil!)
    // Order matters in our case below
    if ( dr == RF_DR_LOW) {
        // '10' = 250KBPS
        result = RF24_250KBPS ;
    } else if ( dr == RF_DR_HIGH) {
        // '01' = 2MBPS
        result = RF24_2MBPS ;
    } else {
        // '00' = 1MBPS
        result = RF24_1MBPS ;
    }
    return result ;
}

/****************************************************************************/

void RF24::setCRCLength(rf24_crclength_e length)
{
    uint8_t config = read_register(CONFIG) & ~( CRCO | EN_CRC) ;

    if ( length == RF24_CRC_DISABLED ) {
        // Do nothing, we turned it off above.
    } else if ( length == RF24_CRC_8 ) {
        config |= EN_CRC;
    } else {
        config |= EN_CRC;
        config |= CRCO;
    }
    write_register( CONFIG, config ) ;
    
    printf("CRC SET: %u\n\r", config);
}

/****************************************************************************/

rf24_crclength_e RF24::getCRCLength(void)
{
    rf24_crclength_e result = RF24_CRC_DISABLED;
    uint8_t config = read_register(CONFIG) & ( CRCO | EN_CRC) ;

    if ( config & EN_CRC) {
        if ( config & CRCO )
            result = RF24_CRC_16;
        else
            result = RF24_CRC_8;
    }

    return result;
}

/****************************************************************************/

void RF24::disableCRC( void )
{
    uint8_t disable = read_register(CONFIG) & ~EN_CRC ;
    write_register( CONFIG, disable ) ;
}

/****************************************************************************/
void RF24::setRetries(uint8_t delay, uint8_t count)
{
    write_register(SETUP_RETR,(delay&0xf)<<ARD | (count&0xf)<<ARC);
}

int RF24::min(int a, int b)
{
    if(a < b)
        return a;
    else
        return b;
}