lt8920_test/modules/lt8920/lt8920.cpp

#include "stm32l0xx_hal.h"
#include "lt8920.h"
#include "lt8920_trs.h"
#include <stdio.h>


#undef DBG
#define DBG if(0)




void LT8920::dump_register(uint8_t reg) 
{
    uint16_t r = readRegister(reg);
    printf("reg: %u, value: %X\r\n", reg, r);
}

LT8920::LT8920(void)
{
    _channel = DEFAULT_CHANNEL;
    
    LT8920_CS_HIGH;
}

void LT8920::begin()
{
    LT8920_RESET_LOW;
    HAL_Delay(200);
    LT8920_RESET_HIGH;
    HAL_Delay(200);  
    
    //setup

    writeRegister(0, 0x6fe0);
    writeRegister(1, 0x5681);
    writeRegister(2, 0x6617);
    writeRegister(4, 0x9cc9);    //why does this differ from powerup (5447)
    writeRegister(5, 0x6637);    //why does this differ from powerup (f000)
    writeRegister(8, 0x6c90);    //power (default 71af) UNDOCUMENTED
    
    setCurrentControl(4, 0);     // power & gain.
    
    writeRegister(10, 0x7ffd);   //bit 0: XTAL OSC enable
    writeRegister(11, 0x0000);   //bit 8: Power down RSSI (0=  RSSI operates normal)
    writeRegister(12, 0x0000);
    writeRegister(13, 0x48bd);   //(default 4855)
    
    writeRegister(22, 0x00ff);
    writeRegister(23, 0x8005);  //bit 2: Calibrate VCO before each Rx/Tx enable
    writeRegister(24, 0x0067);
    writeRegister(25, 0x1659);
    writeRegister(26, 0x19e0);
    writeRegister(27, 0x1300);  //bits 5:0, Crystal Frequency adjust
    writeRegister(28, 0x1800);
    
    //fedcba9876543210
    writeRegister(32, 0x5000);  //AAABBCCCDDEEFFFG  A preamble length, B, syncword length, c trailer length, d packet type
    //                  E FEC_type, F BRCLK_SEL, G reserved
    //0x5000 = 0101 0000 0000 0000 = preamble 010 (3 bytes), B 10 (48 bits)
    writeRegister(33, 0x3fc7);
    writeRegister(34, 0x2000);  //
    writeRegister(35, 0x0300);  //POWER mode,  bit 8/9 on = retransmit = 3x (default)
    setSyncWord(0x03805a5a03800380);
    
    writeRegister(40, 0x4401);  //max allowed error bits = 0 (01 = 0 error bits)
    writeRegister(R_PACKETCONFIG, PACKETCONFIG_CRC_ON |
                  PACKETCONFIG_PACK_LEN_ENABLE | PACKETCONFIG_FW_TERM_TX);
    
    writeRegister(42, 0xfdb0);
    writeRegister(43, 0x000f);
    
    //setDataRate(LT8920_1MBPS);
    
    writeRegister(R_FIFO, 0x0000);  //TXRX_FIFO_REG (FIFO queue)
    
    writeRegister(R_FIFO_CONTROL, 0x8080); //Fifo Rx/Tx queue reset
    
    HAL_Delay(200);
    writeRegister(R_CHANNEL, _BV(CHANNEL_TX_BIT));  //set TX mode.  (TX = bit 8, RX = bit 7, so RX would be 0x0080)
    HAL_Delay(2);
    writeRegister(R_CHANNEL, _channel);  // Frequency = 2402 + channel
}

void LT8920::setChannel(uint8_t channel)
{
    _channel = channel;
    writeRegister(R_CHANNEL,  (_channel & CHANNEL_MASK));
}

uint8_t LT8920::getChannel()
{
    return _channel;
}

void LT8920::setCurrentControl(uint8_t power, uint8_t gain)
{
    writeRegister(R_CURRENT,
                 ((power << CURRENT_POWER_SHIFT) & CURRENT_POWER_MASK) |
                 ((gain << CURRENT_GAIN_SHIFT) & CURRENT_GAIN_MASK));
}

bool LT8920::setDataRate(DataRate rate)
{
    uint16_t newValue;

    switch (rate)
    {
        case LT8920_1MBPS:
            newValue = DATARATE_1MBPS;
        break;
        case LT8920_250KBPS:
            newValue = DATARATE_250KBPS;
        break;
        case LT8920_125KBPS:
            newValue = DATARATE_125KBPS;
        break;
        case LT8920_62KBPS:
            newValue = DATARATE_62KBPS;
        break;
        default:
            return false;
    }
    
    writeRegister(R_DATARATE, newValue);
    
    return ( (readRegister(R_DATARATE) & DATARATE_MASK) == (newValue & DATARATE_MASK));
}

LT8920::DataRate LT8920::getDataRate()
{
    uint16_t value = readRegister(R_DATARATE) & DATARATE_MASK;
    
    switch (value)
    {
        case DATARATE_1MBPS:
            return LT8920_1MBPS;
        case DATARATE_250KBPS:
            return LT8920_250KBPS;
        case DATARATE_125KBPS:
            return LT8920_125KBPS;
        case DATARATE_62KBPS:
            return LT8920_62KBPS;
        default : 
            return LT8920_ERROR;
    }
}

uint16_t LT8920::readRegister(uint8_t reg)
{
    LT8920_CS_LOW;
    
    lt_spi_transfer_byte(REGISTER_READ | (REGISTER_MASK & reg));
    uint8_t high = lt_spi_transfer_byte(0x00);
    uint8_t low = lt_spi_transfer_byte(0x00);
    LT8920_CS_HIGH;
  
    DBG printf("reg: %X = %X\r\n", reg, (high << 8 | low));

    return (high << 8 | low);
}

uint8_t LT8920::writeRegister(uint8_t reg, uint16_t data)
{
    uint8_t high = data >> 8;
    uint8_t low = data & 0xFF;

    return writeRegister2(reg, high, low);
}

uint8_t LT8920::writeRegister2(uint8_t reg, uint8_t high, uint8_t low)
{
  // char sbuf[32];
  // sprintf_P(sbuf, PSTR("%d => %02x%02x"), reg, high, low);
  // Serial.println(sbuf);

    LT8920_CS_LOW;
    uint8_t result = lt_spi_transfer_byte(REGISTER_WRITE | (REGISTER_MASK & reg));
    lt_spi_transfer_byte(high);
    lt_spi_transfer_byte(low);
    
    LT8920_CS_HIGH;
    return result;
}

void LT8920::sleep()
{
    //set bit 14 on register 35.
    writeRegister(35, readRegister(35) | _BV(14));
}

void LT8920::whatsUp(void)
{
    uint16_t mode = readRegister(R_CHANNEL);
  
    DBG printf("Tx_EN = %u, Rx_EN = %u\r\n", (mode & _BV(CHANNEL_TX_BIT)), (mode & _BV(CHANNEL_RX_BIT)));
    DBG printf("Channel = %u\r\n", (mode & CHANNEL_MASK));  
  
    //read the status register.
    uint16_t state = readRegister(R_STATUS);

    bool crc_error = state & _BV(15);
    bool fec23_error = state & _BV(14);
    uint8_t framer_st = (state & 0b0011111100000000) >> 8;
    bool pkt_flag = state & _BV(6);
    bool fifo_flag = state & _BV(5);

    DBG printf("CRC = %u, FEC = %u, FRAMER_ST = %u, PKT = %u, FIFO = %u\r\n",
               crc_error, fec23_error, framer_st, pkt_flag, fifo_flag);

    uint16_t fifo = readRegister(R_FIFO_CONTROL);
    
    DBG printf("FIFO_WR_PTR = %X, FIFO_RD_PTR = %X\r\n", 
               ((fifo >> 8) & 0b111111), (fifo & 0b111111));
}

bool LT8920::available()
{
  //read the PKT_FLAG state; this can also be done with a hard wire.
    if (LT8920_GET_PKT != 0) {
        return true;
    }

    return false;
}

int LT8920::read(uint8_t *buffer, size_t maxBuffer)
{
    uint16_t value = readRegister(R_STATUS);
    uint8_t pos = 0;
    
    if (bitRead(value, STATUS_CRC_BIT) == 0)
    {
        //CRC ok
        uint16_t data = readRegister(R_FIFO);
        uint8_t packetSize = data >> 8;
        
        if (maxBuffer < packetSize + 1) {
            //BUFFER TOO SMALL
            return -2;
        }
        
        buffer[pos++] = (data & 0xFF);
        
        while (pos < packetSize)
        {
            data = readRegister(R_FIFO);
            buffer[pos++] = data >> 8;
            buffer[pos++] = data & 0xFF;
        }

        return packetSize;
    }
    else {
        //CRC error
        return -1;
    }
}

void LT8920::startListening()
{
    writeRegister(R_CHANNEL, _channel & CHANNEL_MASK);    // turn off rx/tx
    HAL_Delay(3);
    writeRegister(R_FIFO_CONTROL, 0x0080);  //flush rx
    writeRegister(R_CHANNEL,  (_channel & CHANNEL_MASK) | _BV(CHANNEL_RX_BIT));   //enable RX
    HAL_Delay(5);
}

/* set the BRCLK_SEL value */
void LT8920::setClock(uint8_t clock)
{
    //register 32, bits 3:1.
    uint16_t val = readRegister(35);
    val &= 0b1111111111110001;
    val |= ((clock & 0x07) << 1);;

    writeRegister(35, val);
}

bool LT8920::sendPacket(uint8_t *data, size_t packetSize)
{
    if (packetSize < 1 || packetSize > 255)
    {
        return false;
    }

    writeRegister(R_CHANNEL, 0x0000);
    writeRegister(R_FIFO_CONTROL, 0x8000);  //flush tx

    // packets are sent in 16bit words, and the first word will be the packet size.
    // start spitting out words until we are done.

    uint8_t pos = 0;
    writeRegister2(R_FIFO, packetSize, data[pos++]);
  
    while (pos < packetSize)
    {
        uint8_t msb = data[pos++];
        uint8_t lsb = data[pos++];

        writeRegister2(R_FIFO, msb, lsb);
    }

    writeRegister(R_CHANNEL,  (_channel & CHANNEL_MASK) | _BV(CHANNEL_TX_BIT));   //enable TX

    // Wait until the packet is sent.
    while (LT8920_GET_PKT == 0)
    {
        //do nothing.
    }

    return true;
}

void LT8920::setSyncWord(uint64_t syncWord)
{
    writeRegister(R_SYNCWORD1, syncWord);
    writeRegister(R_SYNCWORD2, syncWord >> 16);
    writeRegister(R_SYNCWORD3, syncWord >> 32);
    writeRegister(R_SYNCWORD4, syncWord >> 48);
}

void LT8920::setSyncWordLength(uint8_t option)
{
    option &= 0x03;
    option <<= 11;

    writeRegister(32, (readRegister(32) & 0b0001100000000000) | option);
}

uint8_t LT8920::getRSSI()
{
    // RSSI: 15:10
    uint16_t value = readRegister(6);

    return (value >> 10);
}

void LT8920::scanRSSI(uint16_t *buffer, uint8_t start_channel, uint8_t num_channels)
{
    uint8_t pos = 0;
    
    // writeRegister(R_CHANNEL, _BV(CHANNEL_RX_BIT));
    //
    // //add read mode.
    writeRegister(R_FIFO_CONTROL, 0x8080);  //flush rx
    // writeRegister(R_CHANNEL, 0x0000);

    //set number of channels to scan.
    writeRegister(42, (readRegister(42) & 0b0000001111111111) | ((num_channels-1 & 0b111111) << 10));

    //set channel scan offset.
    writeRegister(43, (readRegister(43) & 0b0000000011111111) | ((start_channel & 0b1111111) << 8));
    writeRegister(43, (readRegister(43) & 0b0111111111111111) | _BV(15));

    while (LT8920_GET_PKT == 0) {}

    //read the results.
    while (pos < num_channels)
    {
        uint16_t data = readRegister(R_FIFO);
        buffer[pos++] = data >> 8;
    }
}