rf24-pio/RF24.cpp

/*
 Copyright (C) 2011 James Coliz, Jr. <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 <WProgram.h>
#include <SPI.h>
#include "RF24.h"
#include "nRF24L01.h"

#undef SERIAL_DEBUG
#ifdef SERIAL_DEBUG
#define IF_SERIAL_DEBUG(x) ({x;})
#else
#define IF_SERIAL_DEBUG(x)
#endif

// Avoid spurious warnings
#undef PROGMEM
#define PROGMEM __attribute__(( section(".progmem.data") ))
#undef PSTR
#define PSTR(s) (__extension__({static prog_char __c[] PROGMEM = (s); &__c[0];}))

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

void RF24::csn(int mode)
{
  SPI.setDataMode(SPI_MODE0);
  SPI.setClockDivider(SPI_CLOCK_DIV8);
  digitalWrite(csn_pin,mode);
}

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

void RF24::ce(int mode)
{
  digitalWrite(ce_pin,mode);
}

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

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

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

  csn(HIGH);

  return status;
}

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

uint8_t RF24::read_register(uint8_t reg)
{
  csn(LOW);
  SPI.transfer( R_REGISTER | ( REGISTER_MASK & reg ) );
  uint8_t result = SPI.transfer(0xff);

  csn(HIGH);
  return result;
}

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

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

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

  csn(HIGH);

  return status;
}

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

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

  IF_SERIAL_DEBUG(printf_P(PSTR("write_register(%02x,%02x)\n\r"),reg,value));

  csn(LOW);
  status = SPI.transfer( W_REGISTER | ( REGISTER_MASK & reg ) );
  SPI.transfer(value);
  csn(HIGH);

  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);

  csn(LOW);
  status = SPI.transfer( W_TX_PAYLOAD );
  uint8_t data_len = min(len,payload_size);
  while ( data_len-- )
    SPI.transfer(*current++);

  // This does not seem to be needed.  Keeping it here in case
  // removing it does cause problems for static payloads
  //
  // Send blanks out to the chip to finish off the payload 
  //uint8_t blank_len = payload_size - data_len;
  //while ( blank_len-- )
  //  SPI.transfer(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);

  csn(LOW);
  status = SPI.transfer( R_RX_PAYLOAD );
  uint8_t data_len = min(len,payload_size);
  while ( data_len-- )
    *current++ = SPI.transfer(0xff);
  
  // This does not seem to be needed.  Keeping it here in case
  // removing it does cause problems for static payloads
  //
  // Read the remaining payload off the chip, even though we will
  // throw it away.
  //uint8_t blank_len = payload_size - data_len;
  //while ( blank_len-- )
  //  SPI.transfer(0xff);
  
  csn(HIGH);

  return status;
}

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

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

  csn(LOW);
  status = SPI.transfer( FLUSH_RX );
  csn(HIGH);

  return status;
}

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

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

  csn(LOW);
  status = SPI.transfer( FLUSH_TX );
  csn(HIGH);

  return status;
}

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

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

  csn(LOW);
  status = SPI.transfer( NOP );
  csn(HIGH);

  return status;
}

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

void RF24::print_status(uint8_t status)
{
  printf_P(PSTR("STATUS\t\t = 0x%02x RX_DR=%x TX_DS=%x MAX_RT=%x RX_P_NO=%x TX_FULL=%x\n\r"),
           status,
           (status & _BV(RX_DR))?1:0,
           (status & _BV(TX_DS))?1:0,
           (status & _BV(MAX_RT))?1:0,
           ((status >> RX_P_NO) & B111),
           (status & _BV(TX_FULL))?1:0
          );
}

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

void RF24::print_observe_tx(uint8_t value)
{
  printf_P(PSTR("OBSERVE_TX=%02x: POLS_CNT=%x ARC_CNT=%x\n\r"),
           value,
           (value >> PLOS_CNT) & B1111,
           (value >> ARC_CNT) & B1111
          );
}

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

void RF24::print_byte_register(prog_char* name, uint8_t reg, uint8_t qty)
{
  char extra_tab = strlen_P(name) < 8 ? '\t' : 0;
  printf_P(PSTR("%S\t%c ="),name,extra_tab);
  while (qty--)
    printf_P(PSTR(" 0x%02x"),read_register(reg++));
  printf_P(PSTR("\n\r"));
}

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

void RF24::print_address_register(prog_char* name, uint8_t reg, uint8_t qty)
{
  char extra_tab = strlen_P(name) < 8 ? '\t' : 0;
  printf_P(PSTR("%S\t%c ="),name,extra_tab);

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

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

  printf_P(PSTR("\n\r"));
}

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

RF24::RF24(uint8_t _cepin, uint8_t _cspin):
  ce_pin(_cepin), csn_pin(_cspin), payload_size(32), ack_payload_available(false)
{
}

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

void RF24::setChannel(uint8_t channel)
{
  write_register(RF_CH,min(channel,127));
}

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

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

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

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

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

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

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

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

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

void RF24::begin(void)
{
  pinMode(ce_pin,OUTPUT);
  pinMode(csn_pin,OUTPUT);

  ce(LOW);
  csn(HIGH);

  SPI.begin();
  SPI.setBitOrder(MSBFIRST);
  SPI.setDataMode(SPI_MODE0);
  SPI.setClockDivider(SPI_CLOCK_DIV8);

  // Set generous timeouts, to make testing a little easier
  write_register(SETUP_RETR,(B1111 << ARD) | (B1111 << ARC));

  // Reset current status
  write_register(STATUS,_BV(RX_DR) | _BV(TX_DS) | _BV(MAX_RT) );

  // Initialize CRC
  write_register(CONFIG, _BV(EN_CRC) );

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

  // Set up default configuration.  Callers can always change it later.
  setChannel(1);
}

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

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

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

  // Flush buffers
  flush_rx();

  // Go!
  ce(HIGH);

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

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

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

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

void RF24::powerDown(void)
{
  write_register(CONFIG,read_register(CONFIG) & ~_BV(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.

  uint8_t observe_tx;
  uint8_t status;
  uint32_t sent_at = millis();
  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 & ( _BV(TX_DS) | _BV(MAX_RT) ) ) && ( millis() - 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, ack_payload_available;
  whatHappened(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) | _BV(PWR_UP) ) & ~_BV(PRIM_RX) );
  delay(2);

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

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

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

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

  csn(LOW);
  SPI.transfer( R_RX_PL_WID );
  result = SPI.transfer(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 & _BV(RX_DR) );

  if (result)
  {
    // If the caller wants the pipe number, include that
    if ( pipe_num )
      *pipe_num = ( status >> RX_P_NO ) & B111;

    // Clear the status bit

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

    write_register(STATUS,_BV(RX_DR) );

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

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

void RF24::whatHappened(bool& tx_ok,bool& tx_fail,bool& rx_ready)
{
  // Read the status & reset the status in one easy call
  uint8_t status = write_register(STATUS,_BV(RX_DR) | _BV(TX_DS) | _BV(MAX_RT) );

  // Report to the user what happened
  tx_ok = status & _BV(TX_DS);
  tx_fail = status & _BV(MAX_RT);
  rx_ready = status & _BV(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);
  write_register(RX_PW_P0,min(payload_size,32));
}

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

void RF24::openReadingPipe(uint8_t child, uint64_t value)
{
  const uint8_t child_pipe[] =
  {
    RX_ADDR_P0, RX_ADDR_P1, RX_ADDR_P2, RX_ADDR_P3, RX_ADDR_P4, RX_ADDR_P5
  };
  const uint8_t child_payload_size[] =
  {
    RX_PW_P0, RX_PW_P1, RX_PW_P2, RX_PW_P3, RX_PW_P4, RX_PW_P5
  };
  const uint8_t child_pipe_enable[] =
  {
    ERX_P0, ERX_P1, ERX_P2, ERX_P3, ERX_P4, ERX_P5
  };

  // 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 = value;

  if (child <= 5)
  {
    // For pipes 2-5, only write the LSB
    if ( child < 2 )
      write_register(child_pipe[child], reinterpret_cast<uint8_t*>(&value), 5);
    else
      write_register(child_pipe[child], reinterpret_cast<uint8_t*>(&value), 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) | _BV(child_pipe_enable[child]));
  }
}

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

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

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

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

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

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

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

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

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

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

  write_register(DYNPD,read_register(DYNPD) | _BV(DPL_P1) | _BV(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.transfer( W_ACK_PAYLOAD | ( pipe & B111 ) );
  uint8_t data_len = min(len,32);
  while ( data_len-- )
    SPI.transfer(*current++);

  csn(HIGH);
}

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

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

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

void RF24::setAutoAck(bool enable)
{
  if ( enable )
    write_register(EN_AA, B111111);
  else
    write_register(EN_AA, 0);
}

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

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

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

void RF24::setDataRate(rf24_datarate_e speed)
{
  uint8_t setup = read_register(RF_SETUP) & _BV(RF_DR);
  if (speed == RF24_2MBPS)
    setup |= _BV(RF_DR);
  write_register(RF_SETUP,setup);

}

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

void RF24::setCRCLength(rf24_crclength_e length)
{
  uint8_t config = read_register(CONFIG) & _BV(CRCO);
  if (length == RF24_CRC_16)
    config |= _BV(CRCO);
  write_register(CONFIG,config);
}

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

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

// vim:ai:cin:sts=2 sw=2 ft=cpp