upm/src/nrf24l01/nrf24l01.cxx

/*
 * Author: Yevgeniy Kiveisha <yevgeniy.kiveisha@intel.com>
 * Copyright (c) 2014 Intel Corporation.
 * BLE Beaconing based on http://dmitry.gr/index.php?r=05.Projects&proj=11.%20Bluetooth%20LE%20fakery
 *
 * Permission is hereby granted, free of charge, to any person obtaining
 * a copy of this software and associated documentation files (the
 * "Software"), to deal in the Software without restriction, including
 * without limitation the rights to use, copy, modify, merge, publish,
 * distribute, sublicense, and/or sell copies of the Software, and to
 * permit persons to whom the Software is furnished to do so, subject to
 * the following conditions:
 *
 * The above copyright notice and this permission notice shall be
 * included in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
 * LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
 * OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
 * WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
 */

#include <iostream>
#include <unistd.h>
#include <stdlib.h>

#include "nrf24l01.h"

using namespace upm;

NRF24L01::NRF24L01 (uint8_t cs, uint8_t ce)
                            : m_csnPinCtx(cs), m_cePinCtx(ce), m_spi(0)
{
    mraa::init();
    init (cs, ce);
}

void
NRF24L01::init (uint8_t chip_select, uint8_t chip_enable) {
    mraa::Result error = mraa::SUCCESS;

    m_csn       = chip_select;
    m_ce        = chip_enable;
    m_channel   = 99;

    error = m_csnPinCtx.dir(mraa::DIR_OUT);
    if (error != mraa::SUCCESS) {
        mraa::printError (error);
    }

    error = m_cePinCtx.dir(mraa::DIR_OUT);
    if (error != mraa::SUCCESS) {
        mraa::printError (error);
    }

    ceLow();
    csOff ();
}

void
NRF24L01::configure () {
    /* Set RF channel */
    setRegister (RF_CH, m_channel);

    /* Set length of incoming payload */
    setRegister (RX_PW_P0, m_payload);

    /* Set length of incoming payload for broadcast */
    setRegister (RX_PW_P1, m_payload);

    /* Start receiver */
    rxPowerUp ();
    rxFlushBuffer ();
}

void
NRF24L01::send (uint8_t * value) {
    uint8_t status;
    status = getStatus();

    while (m_ptx) {
        status = getStatus();

        if((status & ((1 << TX_DS)  | (1 << MAX_RT)))){
            m_ptx = 0;
            break;
        }
    } // Wait until last paket is send

    ceLow ();
    txPowerUp (); // Set to transmitter mode , Power up
    txFlushBuffer ();

    csOn ();
    m_spi.writeByte(W_TX_PAYLOAD); // Write cmd to write payload
    writeBytes (value, NULL, m_payload); // Write payload
    csOff ();
    ceHigh(); // Start transmission

    while (dataSending ()) { }

    usleep (10000);
}

void
NRF24L01::send () {
    send (m_txBuffer);
}

void
NRF24L01::setSourceAddress (uint8_t * addr) {
    ceLow ();
    writeRegister (RX_ADDR_P0, addr, ADDR_LEN);
    ceHigh ();
}

void
NRF24L01::setDestinationAddress (uint8_t * addr) {
    writeRegister (TX_ADDR, addr, ADDR_LEN);
}

void
NRF24L01::setBroadcastAddress (uint8_t * addr) {
    writeRegister (RX_ADDR_P1, addr, ADDR_LEN);
}

void
NRF24L01::setPayload (uint8_t payload) {
    m_payload = payload;
}

bool
NRF24L01::dataReady () {
    /* See note in getData() function - just checking RX_DR isn't good enough */
    uint8_t status = getStatus();
    /* We can short circuit on RX_DR, but if it's not set, we still need
     * to check the FIFO for any pending packets */
    if ( status & (1 << RX_DR) ) {
        return 1;
    }

    return !rxFifoEmpty();
}

bool
NRF24L01::dataSending () {
    uint8_t status;
    if(m_ptx)   { // Sending mode.
        status = getStatus();
        /* if sending successful (TX_DS) or max retries exceded (MAX_RT). */
        if((status & ((1 << TX_DS)  | (1 << MAX_RT)))){
            rxPowerUp ();
            return false;
        }
        return true;
    }
    return false;
}

void
NRF24L01::getData (uint8_t * data)  {
    csOn ();
    /* Send cmd to read rx payload */
    m_spi.writeByte(R_RX_PAYLOAD);
    /* Read payload */
    writeBytes (data, data, m_payload);
    csOff ();
    /* NVI: per product spec, p 67, note c:
     * "The RX_DR IRQ is asserted by a new packet arrival event. The procedure
     * for handling this interrupt should be: 1) read payload through SPI,
     * 2) clear RX_DR IRQ, 3) read FIFO_STATUS to check if there are more
     * payloads available in RX FIFO, 4) if there are more data in RX FIFO,
     * repeat from step 1)."
     * So if we're going to clear RX_DR here, we need to check the RX FIFO
     * in the dataReady() function */
    /* Reset status register */
    setRegister (STATUS, (1<<RX_DR));
}

uint8_t
NRF24L01::getStatus() {
    return getRegister (STATUS);
}

bool
NRF24L01::rxFifoEmpty () {
    uint8_t fifoStatus = getRegister (FIFO_STATUS);
    return (fifoStatus & (1 << RX_EMPTY));
}

void
NRF24L01::rxPowerUp () {
    m_ptx = 0;
    ceLow ();
    setRegister (CONFIG, _CONFIG | ( (1 << PWR_UP) | (1 << PRIM_RX) ));
    ceHigh ();
    setRegister (STATUS, (1 << TX_DS) | (1 << MAX_RT));
}

void
NRF24L01::rxFlushBuffer () {
    sendCommand (FLUSH_RX);
}

void
NRF24L01::txPowerUp () {
    m_ptx = 1;
    setRegister (CONFIG, _CONFIG | ( (1 << PWR_UP) | (0 << PRIM_RX) ));
}

void
NRF24L01::powerDown(){
    ceLow ();
    setRegister (CONFIG, _CONFIG);
}

void
NRF24L01::setChannel (uint8_t channel) {
    m_channel = channel;
    setRegister (RF_CH, channel);
}

void
NRF24L01::setPower (power_t power) {
    uint8_t setupRegisterData = 0;

    switch (power) {
        case NRF_0DBM:
            m_power = 3;
        break;
        case NRF_6DBM:
            m_power = 2;
        break;
        case NRF_12DBM:
            m_power = 1;
        break;
        case NRF_18DBM:
            m_power = 0;
        break;
    }

    setupRegisterData = getRegister (RF_SETUP); // Read current value.
    setupRegisterData &= 0xFC; // Erase the old value;
    setupRegisterData |= (m_power & 0x3);
    setRegister (RF_SETUP, setupRegisterData); // Write the new value.
}

uint8_t
NRF24L01::setSpeedRate (speed_rate_t rate) {
    uint8_t setupRegisterData = 0;

    setupRegisterData = getRegister (RF_SETUP); // Read current value.
    setupRegisterData &= ~((1 << RF_DR_LOW) | (1 << RF_DR_HIGH));

    switch (rate) {
        case NRF_250KBPS:
            setupRegisterData |= (1 << RF_DR_LOW) ;
        break;
        case NRF_1MBPS:
        break;
        case NRF_2MBPS:
            setupRegisterData |= (1 << RF_DR_HIGH);
        break;
    }

    setRegister (RF_SETUP, setupRegisterData); // Write the new value.

    if (setupRegisterData == getRegister (RF_SETUP)) {
        return 0x0;
    }

    return 0x1;
}

mraa::Result
NRF24L01::ceHigh () {
    return m_cePinCtx.write(HIGH);
}

mraa::Result
NRF24L01::ceLow () {
    return m_cePinCtx.write(LOW);
}

mraa::Result
NRF24L01::csOn () {
    return m_csnPinCtx.write(LOW);
}

mraa::Result
NRF24L01::csOff () {
    return m_csnPinCtx.write(HIGH);
}

void
NRF24L01::pollListener() {
    if (dataReady()) {
        getData (m_rxBuffer);
        dataRecievedHandler (); /* let know that data arrived */
    }
}

void
NRF24L01::txFlushBuffer () {
    sendCommand (FLUSH_TX);
}

void
NRF24L01::setBeaconingMode () {
    setRegister (CONFIG,     0x12); // on, no crc, int on RX/TX done
    setRegister (EN_AA,      0x00); // no auto-acknowledge
    setRegister (EN_RXADDR,  0x00); // no RX
    setRegister (SETUP_AW,   0x02); // 5-byte address
    setRegister (SETUP_RETR, 0x00); // no auto-retransmit
    setRegister (RF_SETUP,   0x06); // 1MBps at 0dBm
    setRegister (STATUS,     0x3E); // clear various flags
    setRegister (DYNPD,      0x00); // no dynamic payloads
    setRegister (FEATURE,    0x00); // no features
    setRegister (RX_PW_P0,   32);   // always RX 32 bytes
    setRegister (EN_RXADDR,  0x01); // RX on pipe 0

    uint8_t addr[4] = { swapbits(0x8E), swapbits(0x89), swapbits(0xBE), swapbits(0xD6)};
    writeRegister (TX_ADDR,     addr, 4);
    writeRegister (RX_ADDR_P0,  addr, 4);

    uint8_t index = 0;
    m_bleBuffer[index++] = 0x42;        // PDU type, given address is random
    m_bleBuffer[index++] = 0x1B;        // 6+3+2+16 = 27 bytes of payload

    m_bleBuffer[index++] = BLE_MAC_0;
    m_bleBuffer[index++] = BLE_MAC_1;
    m_bleBuffer[index++] = BLE_MAC_2;
    m_bleBuffer[index++] = BLE_MAC_3;
    m_bleBuffer[index++] = BLE_MAC_4;
    m_bleBuffer[index++] = BLE_MAC_5;

    m_bleBuffer[index++] = 2;           // flags (LE-only, limited discovery mode)
    m_bleBuffer[index++] = 0x01;
    m_bleBuffer[index++] = 0x05;

    m_bleBuffer[index++] = 17;
    m_bleBuffer[index++] = 0x08;
}

void
NRF24L01::sendBeaconingMsg (uint8_t * msg) {
    const uint8_t   chRf[] = {2, 26,80};
    const uint8_t   chLe[] = {37,38,39};
    uint8_t         index = BLE_PAYLOAD_OFFSET + 16;

    memcpy (&m_bleBuffer[BLE_PAYLOAD_OFFSET], msg, 16);
    m_bleBuffer[index++] = 0x55;
    m_bleBuffer[index++] = 0x55;
    m_bleBuffer[index++] = 0x55;

    uint8_t channel = 0;
    while (++channel != sizeof(chRf)) {
        setRegister (RF_CH,     chRf[channel]);
        setRegister (STATUS,    0x6E);          //clear flags

        blePacketEncode (m_bleBuffer, index, chLe[channel]);

        sendCommand (FLUSH_TX); // Clear RX Fifo
        sendCommand (FLUSH_RX); // Clear TX Fifo

        csOn ();
        m_spi.writeByte(W_TX_PAYLOAD);        // Write cmd to write payload
        writeBytes (m_bleBuffer, NULL, 32);     // Write payload
        csOff ();

        setRegister (CONFIG, 0x12);             // tx on
        ceHigh ();                              // Start transmission
        usleep (10000);
        ceLow ();
    }
}

/*
 * ---------------
 * PRIVATE SECTION
 * ---------------
 */

void
NRF24L01::writeBytes (uint8_t * dataout, uint8_t * datain, uint8_t len) {
    for (uint8_t i = 0; i < len; i++) {
        if (datain != NULL) {
            datain[i] = m_spi.writeByte(dataout[i]);
        } else {
            m_spi.writeByte(dataout[i]);
        }
    }
}

void
NRF24L01::setRegister (uint8_t reg, uint8_t value) {
    csOn ();
    m_spi.writeByte(W_REGISTER | (REGISTER_MASK & reg));
    m_spi.writeByte(value);
    csOff ();
}

uint8_t
NRF24L01::getRegister (uint8_t reg) {
    uint8_t data = 0;

    csOn ();
    m_spi.writeByte(R_REGISTER | (REGISTER_MASK & reg));
    data = m_spi.writeByte(data);
    csOff ();

    return data;
}

void
NRF24L01::readRegister (uint8_t reg, uint8_t * value, uint8_t len) {
    csOn ();
    m_spi.writeByte(R_REGISTER | (REGISTER_MASK & reg));
    writeBytes (value, value, len);
    csOff ();
}

void
NRF24L01::writeRegister (uint8_t reg, uint8_t * value, uint8_t len) {
    csOn ();
    m_spi.writeByte(W_REGISTER | (REGISTER_MASK & reg));
    writeBytes (value, NULL, len);
    csOff ();
}

void
NRF24L01::sendCommand (uint8_t cmd) {
    csOn ();
    m_spi.writeByte(cmd);
    csOff ();
}

void
NRF24L01::bleCrc (const uint8_t* data, uint8_t len, uint8_t* dst) {
    uint8_t v, t, d;
    while(len--) {
        d = *data++;
        for(v = 0; v < 8; v++, d >>= 1){
            t = dst[0] >> 7;
            dst[0] <<= 1;
            if(dst[1] & 0x80) dst[0] |= 1;
            dst[1] <<= 1;
            if(dst[2] & 0x80) dst[1] |= 1;
            dst[2] <<= 1;

            if(t != (d & 1)) {
                dst[2] ^= 0x5B;
                dst[1] ^= 0x06;
            }
        }
    }
}

void
NRF24L01::bleWhiten (uint8_t* data, uint8_t len, uint8_t whitenCoeff) {
    uint8_t  m;
    while(len--) {
        for(m = 1; m; m <<= 1) {
            if(whitenCoeff & 0x80){
                whitenCoeff ^= 0x11;
                (*data) ^= m;
            }
            whitenCoeff <<= 1;
        }
        data++;
    }
}

void
NRF24L01::blePacketEncode(uint8_t* packet, uint8_t len, uint8_t chan) {
    //length is of packet, including crc. pre-populate crc in packet with initial crc value!
    uint8_t i, dataLen = len - 3;

    bleCrc(packet, dataLen, packet + dataLen);
    for(i = 0; i < 3; i++, dataLen++) {
        packet[dataLen] = swapbits(packet[dataLen]);
    }

    bleWhiten(packet, len, (swapbits(chan) | 2));
    for(i = 0; i < len; i++) {
        packet[i] = swapbits(packet[i]);
    }
}

uint8_t
NRF24L01::swapbits(uint8_t a) {
    uint8_t v = 0;

    if(a & 0x80) v |= 0x01;
    if(a & 0x40) v |= 0x02;
    if(a & 0x20) v |= 0x04;
    if(a & 0x10) v |= 0x08;
    if(a & 0x08) v |= 0x10;
    if(a & 0x04) v |= 0x20;
    if(a & 0x02) v |= 0x40;
    if(a & 0x01) v |= 0x80;

    return v;
}