PMW3901.cpp

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#include "PMW3901.hpp"

static constexpr uint32_t TIME_us_TSWW = 11; //  - actually 10.5us

PMW3901::PMW3901(int bus, enum Rotation yaw_rotation) :
    SPI("PMW3901", PMW3901_DEVICE_PATH, bus, PMW3901_SPIDEV, SPIDEV_MODE0, PMW3901_SPI_BUS_SPEED),
    ScheduledWorkItem(MODULE_NAME, px4::device_bus_to_wq(get_device_id())),
    _sample_perf(perf_alloc(PC_ELAPSED, "pmw3901: read")),
    _comms_errors(perf_alloc(PC_COUNT, "pmw3901: com err")),
    _yaw_rotation(yaw_rotation)
{
}

PMW3901::~PMW3901()
{
    // make sure we are truly inactive
    stop();

    // free perf counters
    perf_free(_sample_perf);
    perf_free(_comms_errors);
}

int
PMW3901::sensorInit()
{
    uint8_t data[5] {};

    // Power on reset
    writeRegister(0x3A, 0x5A);
    usleep(5000);

    // Reading the motion registers one time
    readRegister(0x02, &data[0], 1);
    readRegister(0x03, &data[1], 1);
    readRegister(0x04, &data[2], 1);
    readRegister(0x05, &data[3], 1);
    readRegister(0x06, &data[4], 1);

    usleep(1000);

    // set performance optimization registers
    // from PixArt PMW3901MB Optical Motion Tracking chip demo kit V3.20 (21 Aug 2018)
    unsigned char v = 0;
    unsigned char c1 = 0;
    unsigned char c2 = 0;

    writeRegister(0x7F, 0x00);
    writeRegister(0x55, 0x01);
    writeRegister(0x50, 0x07);
    writeRegister(0x7f, 0x0e);
    writeRegister(0x43, 0x10);

    readRegister(0x67, &v, 1);

    // if bit7 is set
    if (v & (1 << 7)) {
        writeRegister(0x48, 0x04);

    } else {
        writeRegister(0x48, 0x02);
    }

    writeRegister(0x7F, 0x00);
    writeRegister(0x51, 0x7b);
    writeRegister(0x50, 0x00);
    writeRegister(0x55, 0x00);

    writeRegister(0x7F, 0x0e);
    readRegister(0x73, &v, 1);

    if (v == 0) {
        readRegister(0x70, &c1, 1);

        if (c1 <= 28) {
            c1 = c1 + 14;

        } else {
            c1 = c1 + 11;
        }

        if (c1 > 0x3F) {
            c1 = 0x3F;
        }

        readRegister(0x71, &c2, 1);
        c2 = ((unsigned short)c2 * 45) / 100;

        writeRegister(0x7f, 0x00);
        writeRegister(0x61, 0xAD);
        writeRegister(0x51, 0x70);
        writeRegister(0x7f, 0x0e);
        writeRegister(0x70, c1);
        writeRegister(0x71, c2);
    }

    writeRegister(0x7F, 0x00);
    writeRegister(0x61, 0xAD);
    writeRegister(0x7F, 0x03);
    writeRegister(0x40, 0x00);
    writeRegister(0x7F, 0x05);
    writeRegister(0x41, 0xB3);
    writeRegister(0x43, 0xF1);
    writeRegister(0x45, 0x14);
    writeRegister(0x5B, 0x32);
    writeRegister(0x5F, 0x34);
    writeRegister(0x7B, 0x08);
    writeRegister(0x7F, 0x06);
    writeRegister(0x44, 0x1B);
    writeRegister(0x40, 0xBF);
    writeRegister(0x4E, 0x3F);
    writeRegister(0x7F, 0x08);
    writeRegister(0x65, 0x20);
    writeRegister(0x6A, 0x18);
    writeRegister(0x7F, 0x09);
    writeRegister(0x4F, 0xAF);
    writeRegister(0x5F, 0x40);
    writeRegister(0x48, 0x80);
    writeRegister(0x49, 0x80);
    writeRegister(0x57, 0x77);
    writeRegister(0x60, 0x78);
    writeRegister(0x61, 0x78);
    writeRegister(0x62, 0x08);
    writeRegister(0x63, 0x50);
    writeRegister(0x7F, 0x0A);
    writeRegister(0x45, 0x60);
    writeRegister(0x7F, 0x00);
    writeRegister(0x4D, 0x11);
    writeRegister(0x55, 0x80);
    writeRegister(0x74, 0x21);
    writeRegister(0x75, 0x1F);
    writeRegister(0x4A, 0x78);
    writeRegister(0x4B, 0x78);
    writeRegister(0x44, 0x08);
    writeRegister(0x45, 0x50);
    writeRegister(0x64, 0xFF);
    writeRegister(0x65, 0x1F);
    writeRegister(0x7F, 0x14);
    writeRegister(0x65, 0x67);
    writeRegister(0x66, 0x08);
    writeRegister(0x63, 0x70);
    writeRegister(0x7F, 0x15);
    writeRegister(0x48, 0x48);
    writeRegister(0x7F, 0x07);
    writeRegister(0x41, 0x0D);
    writeRegister(0x43, 0x14);
    writeRegister(0x4B, 0x0E);
    writeRegister(0x45, 0x0F);
    writeRegister(0x44, 0x42);
    writeRegister(0x4C, 0x80);
    writeRegister(0x7F, 0x10);
    writeRegister(0x5B, 0x02);
    writeRegister(0x7F, 0x07);
    writeRegister(0x40, 0x41);
    writeRegister(0x70, 0x00);

    px4_usleep(10000); // delay 10ms

    writeRegister(0x32, 0x44);
    writeRegister(0x7F, 0x07);
    writeRegister(0x40, 0x40);
    writeRegister(0x7F, 0x06);
    writeRegister(0x62, 0xF0);
    writeRegister(0x63, 0x00);
    writeRegister(0x7F, 0x0D);
    writeRegister(0x48, 0xC0);
    writeRegister(0x6F, 0xD5);
    writeRegister(0x7F, 0x00);
    writeRegister(0x5B, 0xA0);
    writeRegister(0x4E, 0xA8);
    writeRegister(0x5A, 0x50);
    writeRegister(0x40, 0x80);

    return PX4_OK;
}

int
PMW3901::init()
{
    // get yaw rotation from sensor frame to body frame
    param_t rot = param_find("SENS_FLOW_ROT");

    if (rot != PARAM_INVALID) {
        int32_t val = 0;
        param_get(rot, &val);

        _yaw_rotation = (enum Rotation)val;
    }

    /* For devices competing with NuttX SPI drivers on a bus (Crazyflie SD Card expansion board) */
    SPI::set_lockmode(LOCK_THREADS);

    /* do SPI init (and probe) first */
    if (SPI::init() != OK) {
        return PX4_ERROR;
    }

    sensorInit();

    _previous_collect_timestamp = hrt_absolute_time();

    start();

    return PX4_OK;
}

int
PMW3901::probe()
{
    uint8_t data[2] {};

    readRegister(0x00, &data[0], 1); // chip id

    // Test the SPI communication, checking chipId and inverse chipId
    if (data[0] == 0x49) {
        return OK;
    }

    // not found on any address
    return -EIO;
}

int
PMW3901::readRegister(unsigned reg, uint8_t *data, unsigned count)
{
    uint8_t cmd[5]; // read up to 4 bytes

    cmd[0] = DIR_READ(reg);

    int ret = transfer(&cmd[0], &cmd[0], count + 1);

    if (OK != ret) {
        perf_count(_comms_errors);
        DEVICE_LOG("spi::transfer returned %d", ret);
        return ret;
    }

    memcpy(&data[0], &cmd[1], count);

    return ret;
}

int
PMW3901::writeRegister(unsigned reg, uint8_t data)
{
    uint8_t cmd[2];                         // write 1 byte
    int ret;

    cmd[0] = DIR_WRITE(reg);
    cmd[1] = data;

    ret = transfer(&cmd[0], nullptr, 2);

    if (OK != ret) {
        perf_count(_comms_errors);
        DEVICE_LOG("spi::transfer returned %d", ret);
        return ret;
    }

    px4_usleep(TIME_us_TSWW);

    return ret;
}

void
PMW3901::Run()
{
    perf_begin(_sample_perf);

    int16_t delta_x_raw = 0;
    int16_t delta_y_raw = 0;
    uint8_t qual = 0;
    float delta_x = 0.0f;
    float delta_y = 0.0f;

    uint64_t timestamp = hrt_absolute_time();
    uint64_t dt_flow = timestamp - _previous_collect_timestamp;
    _previous_collect_timestamp = timestamp;

    _flow_dt_sum_usec += dt_flow;

    readMotionCount(delta_x_raw, delta_y_raw, qual);

    if (qual > 0) {
        _flow_sum_x += delta_x_raw;
        _flow_sum_y += delta_y_raw;
        _flow_sample_counter ++;
        _flow_quality_sum += qual;
    }

    // returns if the collect time has not been reached
    if (_flow_dt_sum_usec < _collect_time) {
        return;
    }

    delta_x = (float)_flow_sum_x / 500.0f;      // proportional factor + convert from pixels to radians
    delta_y = (float)_flow_sum_y / 500.0f;      // proportional factor + convert from pixels to radians

    optical_flow_s report{};
    report.timestamp = timestamp;

    report.pixel_flow_x_integral = static_cast<float>(delta_x);
    report.pixel_flow_y_integral = static_cast<float>(delta_y);

    // rotate measurements in yaw from sensor frame to body frame according to parameter SENS_FLOW_ROT
    float zeroval = 0.0f;
    rotate_3f(_yaw_rotation, report.pixel_flow_x_integral, report.pixel_flow_y_integral, zeroval);
    rotate_3f(_yaw_rotation, report.gyro_x_rate_integral, report.gyro_y_rate_integral, report.gyro_z_rate_integral);

    report.frame_count_since_last_readout = _flow_sample_counter;   // number of frames
    report.integration_timespan = _flow_dt_sum_usec;    // microseconds

    report.sensor_id = 0;
    report.quality = _flow_sample_counter > 0 ? _flow_quality_sum / _flow_sample_counter : 0;


    /* No gyro on this board */
    report.gyro_x_rate_integral = NAN;
    report.gyro_y_rate_integral = NAN;
    report.gyro_z_rate_integral = NAN;

    // set (conservative) specs according to datasheet
    report.max_flow_rate = 5.0f;       // Datasheet: 7.4 rad/s
    report.min_ground_distance = 0.1f; // Datasheet: 80mm
    report.max_ground_distance = 30.0f; // Datasheet: infinity

    _flow_dt_sum_usec = 0;
    _flow_sum_x = 0;
    _flow_sum_y = 0;
    _flow_sample_counter = 0;
    _flow_quality_sum = 0;

    _optical_flow_pub.publish(report);

    perf_end(_sample_perf);
}

int
PMW3901::readMotionCount(int16_t &deltaX, int16_t &deltaY, uint8_t &qual)
{
    uint8_t data[12] = { DIR_READ(0x02), 0, DIR_READ(0x03), 0, DIR_READ(0x04), 0,
                 DIR_READ(0x05), 0, DIR_READ(0x06), 0, DIR_READ(0x07), 0
               };

    int ret = transfer(&data[0], &data[0], 12);

    if (OK != ret) {
        qual = 0;
        perf_count(_comms_errors);
        DEVICE_LOG("spi::transfer returned %d", ret);
        return ret;
    }

    deltaX = ((int16_t)data[5] << 8) | data[3];
    deltaY = ((int16_t)data[9] << 8) | data[7];

    // If the reported flow is impossibly large, we just got garbage from the SPI
    if (deltaX > 240 || deltaY > 240 || deltaX < -240 || deltaY < -240) {
        qual = 0;

    } else {
        qual = data[11];
    }

    ret = OK;

    return ret;
}

void
PMW3901::start()
{
    // schedule a cycle to start things
    ScheduleOnInterval(PMW3901_SAMPLE_INTERVAL, PMW3901_US);
}

void
PMW3901::stop()
{
    ScheduleClear();
}

void
PMW3901::print_info()
{
    perf_print_counter(_sample_perf);
    perf_print_counter(_comms_errors);
}