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ardupilot/libraries/AP_Baro/AP_Baro_MS5611.cpp

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/// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
/*
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/*
originally written by Jose Julio, Pat Hickey and Jordi Muñoz
Heavily modified by Andrew Tridgell
*/
#include <AP_HAL.h>
#include "AP_Baro.h"
extern const AP_HAL::HAL& hal;
#define CMD_MS5611_RESET 0x1E
#define CMD_MS5611_PROM_Setup 0xA0
#define CMD_MS5611_PROM_C1 0xA2
#define CMD_MS5611_PROM_C2 0xA4
#define CMD_MS5611_PROM_C3 0xA6
#define CMD_MS5611_PROM_C4 0xA8
#define CMD_MS5611_PROM_C5 0xAA
#define CMD_MS5611_PROM_C6 0xAC
#define CMD_MS5611_PROM_CRC 0xAE
#define CMD_CONVERT_D1_OSR4096 0x48 // Maximum resolution (oversampling)
#define CMD_CONVERT_D2_OSR4096 0x58 // Maximum resolution (oversampling)
// SPI Device //////////////////////////////////////////////////////////////////
AP_SerialBus_SPI::AP_SerialBus_SPI(enum AP_HAL::SPIDevice device, enum AP_HAL::SPIDeviceDriver::bus_speed speed) :
_device(device),
_speed(speed),
_spi(NULL),
_spi_sem(NULL)
{
}
void AP_SerialBus_SPI::init()
{
_spi = hal.spi->device(_device);
if (_spi == NULL) {
hal.scheduler->panic(PSTR("did not get valid SPI device driver!"));
}
_spi_sem = _spi->get_semaphore();
if (_spi_sem == NULL) {
hal.scheduler->panic(PSTR("AP_SerialBus_SPI did not get valid SPI semaphroe!"));
}
_spi->set_bus_speed(_speed);
}
uint16_t AP_SerialBus_SPI::read_16bits(uint8_t reg)
{
uint8_t tx[3] = { reg, 0, 0 };
uint8_t rx[3];
_spi->transaction(tx, rx, 3);
return ((uint16_t) rx[1] << 8 ) | ( rx[2] );
}
uint32_t AP_SerialBus_SPI::read_24bits(uint8_t reg)
{
uint8_t tx[4] = { reg, 0, 0, 0 };
uint8_t rx[4];
_spi->transaction(tx, rx, 4);
return (((uint32_t)rx[1])<<16) | (((uint32_t)rx[2])<<8) | ((uint32_t)rx[3]);
}
void AP_SerialBus_SPI::write(uint8_t reg)
{
uint8_t tx[1] = { reg };
_spi->transaction(tx, NULL, 1);
}
bool AP_SerialBus_SPI::sem_take_blocking()
{
return _spi_sem->take(10);
}
bool AP_SerialBus_SPI::sem_take_nonblocking()
{
return _spi_sem->take_nonblocking();
}
void AP_SerialBus_SPI::sem_give()
{
_spi_sem->give();
}
/// I2C SerialBus
AP_SerialBus_I2C::AP_SerialBus_I2C(uint8_t addr) :
_addr(addr),
_i2c_sem(NULL)
{
}
void AP_SerialBus_I2C::init()
{
_i2c_sem = hal.i2c->get_semaphore();
if (_i2c_sem == NULL) {
hal.scheduler->panic(PSTR("AP_SerialBus_I2C did not get valid I2C semaphore!"));
}
}
uint16_t AP_SerialBus_I2C::read_16bits(uint8_t reg)
{
uint8_t buf[2];
if (hal.i2c->readRegisters(_addr, reg, sizeof(buf), buf) == 0) {
return (((uint16_t)(buf[0]) << 8) | buf[1]);
}
return 0;
}
uint32_t AP_SerialBus_I2C::read_24bits(uint8_t reg)
{
uint8_t buf[3];
if (hal.i2c->readRegisters(_addr, reg, sizeof(buf), buf) == 0) {
return (((uint32_t)buf[0]) << 16) | (((uint32_t)buf[1]) << 8) | buf[2];
}
return 0;
}
void AP_SerialBus_I2C::write(uint8_t reg)
{
hal.i2c->write(_addr, 1, &reg);
}
bool AP_SerialBus_I2C::sem_take_blocking()
{
return _i2c_sem->take(10);
}
bool AP_SerialBus_I2C::sem_take_nonblocking()
{
return _i2c_sem->take_nonblocking();
}
void AP_SerialBus_I2C::sem_give()
{
_i2c_sem->give();
}
/*
constructor
*/
AP_Baro_MS5611::AP_Baro_MS5611(AP_Baro &baro, AP_SerialBus *serial, bool use_timer) :
AP_Baro_Backend(baro),
_serial(serial),
_updated(false),
_state(0),
_last_timer(0),
_use_timer(use_timer)
{
_instance = _frontend.register_sensor();
_serial->init();
if (!_serial->sem_take_blocking()){
hal.scheduler->panic(PSTR("PANIC: AP_Baro_MS5611: failed to take serial semaphore for init"));
}
_serial->write(CMD_MS5611_RESET);
hal.scheduler->delay(4);
// We read the factory calibration
// The on-chip CRC is not used
C1 = _serial->read_16bits(CMD_MS5611_PROM_C1);
C2 = _serial->read_16bits(CMD_MS5611_PROM_C2);
C3 = _serial->read_16bits(CMD_MS5611_PROM_C3);
C4 = _serial->read_16bits(CMD_MS5611_PROM_C4);
C5 = _serial->read_16bits(CMD_MS5611_PROM_C5);
C6 = _serial->read_16bits(CMD_MS5611_PROM_C6);
if (!_check_crc()) {
hal.scheduler->panic(PSTR("Bad CRC on MS5611"));
}
// Send a command to read Temp first
_serial->write(CMD_CONVERT_D2_OSR4096);
_last_timer = hal.scheduler->micros();
_state = 0;
_s_D1 = 0;
_s_D2 = 0;
_d1_count = 0;
_d2_count = 0;
_serial->sem_give();
if (_use_timer) {
hal.scheduler->register_timer_process(FUNCTOR_BIND_MEMBER(&AP_Baro_MS5611::_timer, void));
}
}
/**
* MS5611 crc4 method based on PX4Firmware code
*/
bool AP_Baro_MS5611::_check_crc(void)
{
int16_t cnt;
uint16_t n_rem;
uint16_t crc_read;
uint8_t n_bit;
uint16_t n_prom[8] = { _serial->read_16bits(CMD_MS5611_PROM_Setup),
C1, C2, C3, C4, C5, C6,
_serial->read_16bits(CMD_MS5611_PROM_CRC) };
n_rem = 0x00;
/* save the read crc */
crc_read = n_prom[7];
/* remove CRC byte */
n_prom[7] = (0xFF00 & (n_prom[7]));
for (cnt = 0; cnt < 16; cnt++) {
/* uneven bytes */
if (cnt & 1) {
n_rem ^= (uint8_t)((n_prom[cnt >> 1]) & 0x00FF);
} else {
n_rem ^= (uint8_t)(n_prom[cnt >> 1] >> 8);
}
for (n_bit = 8; n_bit > 0; n_bit--) {
if (n_rem & 0x8000) {
n_rem = (n_rem << 1) ^ 0x3000;
} else {
n_rem = (n_rem << 1);
}
}
}
/* final 4 bit remainder is CRC value */
n_rem = (0x000F & (n_rem >> 12));
n_prom[7] = crc_read;
/* return true if CRCs match */
return (0x000F & crc_read) == (n_rem ^ 0x00);
}
/*
Read the sensor. This is a state machine
We read one time Temperature (state=1) and then 4 times Pressure (states 2-5)
temperature does not change so quickly...
*/
void AP_Baro_MS5611::_timer(void)
{
// Throttle read rate to 100hz maximum.
if (hal.scheduler->micros() - _last_timer < 10000) {
return;
}
if (!_serial->sem_take_nonblocking()) {
return;
}
if (_state == 0) {
// On state 0 we read temp
uint32_t d2 = _serial->read_24bits(0);
if (d2 != 0) {
_s_D2 += d2;
_d2_count++;
if (_d2_count == 32) {
// we have summed 32 values. This only happens
// when we stop reading the barometer for a long time
// (more than 1.2 seconds)
_s_D2 >>= 1;
_d2_count = 16;
}
}
_state++;
_serial->write(CMD_CONVERT_D1_OSR4096); // Command to read pressure
} else {
uint32_t d1 = _serial->read_24bits(0);;
if (d1 != 0) {
// occasional zero values have been seen on the PXF
// board. These may be SPI errors, but safest to ignore
_s_D1 += d1;
_d1_count++;
if (_d1_count == 128) {
// we have summed 128 values. This only happens
// when we stop reading the barometer for a long time
// (more than 1.2 seconds)
_s_D1 >>= 1;
_d1_count = 64;
}
// Now a new reading exists
_updated = true;
}
_state++;
if (_state == 5) {
_serial->write(CMD_CONVERT_D2_OSR4096); // Command to read temperature
_state = 0;
} else {
_serial->write(CMD_CONVERT_D1_OSR4096); // Command to read pressure
}
}
_last_timer = hal.scheduler->micros();
_serial->sem_give();
}
void AP_Baro_MS5611::update()
{
if (!_use_timer) {
// if we're not using the timer then accumulate one more time
// to cope with the calibration loop and minimise lag
accumulate();
}
if (!_updated) {
return;
}
uint32_t sD1, sD2;
uint8_t d1count, d2count;
// Suspend timer procs because these variables are written to
// in "_update".
hal.scheduler->suspend_timer_procs();
sD1 = _s_D1; _s_D1 = 0;
sD2 = _s_D2; _s_D2 = 0;
d1count = _d1_count; _d1_count = 0;
d2count = _d2_count; _d2_count = 0;
_updated = false;
hal.scheduler->resume_timer_procs();
if (d1count != 0) {
D1 = ((float)sD1) / d1count;
}
if (d2count != 0) {
D2 = ((float)sD2) / d2count;
}
_calculate();
}
// Calculate Temperature and compensated Pressure in real units (Celsius degrees*100, mbar*100).
void AP_Baro_MS5611::_calculate()
{
float dT;
float TEMP;
float OFF;
float SENS;
// Formulas from manufacturer datasheet
// sub -20c temperature compensation is not included
// we do the calculations using floating point
// as this is much faster on an AVR2560, and also allows
// us to take advantage of the averaging of D1 and D1 over
// multiple samples, giving us more precision
dT = D2-(((uint32_t)C5)<<8);
TEMP = (dT * C6)/8388608;
OFF = C2 * 65536.0f + (C4 * dT) / 128;
SENS = C1 * 32768.0f + (C3 * dT) / 256;
if (TEMP < 0) {
// second order temperature compensation when under 20 degrees C
float T2 = (dT*dT) / 0x80000000;
float Aux = TEMP*TEMP;
float OFF2 = 2.5f*Aux;
float SENS2 = 1.25f*Aux;
TEMP = TEMP - T2;
OFF = OFF - OFF2;
SENS = SENS - SENS2;
}
float pressure = (D1*SENS/2097152 - OFF)/32768;
float temperature = (TEMP + 2000) * 0.01f;
_copy_to_frontend(_instance, pressure, temperature);
}
/*
Read the sensor from main code. This is only used for I2C MS5611 to
avoid conflicts on the semaphore from calling it in a timer, which
conflicts with the compass driver use of I2C
*/
void AP_Baro_MS5611::accumulate(void)
{
if (!_use_timer) {
// the timer isn't being called as a timer, so we need to call
// it in accumulate()
_timer();
}
}
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