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353 lines
9.7 KiB
C
353 lines
9.7 KiB
C
/**
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******************************************************************************
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* @addtogroup PIOS PIOS Core hardware abstraction layer
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* @{
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* @addtogroup PIOS_MS5611 MS5611 Functions
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* @brief Hardware functions to deal with the altitude pressure sensor
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* @{
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*
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* @file pios_ms5611.c
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* @author The OpenPilot Team, http://www.openpilot.org Copyright (C) 2012.
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* @brief MS5611 Pressure Sensor Routines
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* @see The GNU Public License (GPL) Version 3
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*
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******************************************************************************/
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/*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 3 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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* or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
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* for more details.
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*
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* You should have received a copy of the GNU General Public License along
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* with this program; if not, write to the Free Software Foundation, Inc.,
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* 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
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*/
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#include "pios.h"
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#ifdef PIOS_INCLUDE_MS5611
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#define POW2(x) (1 << x)
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// TODO: Clean this up. Getting around old constant.
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#define PIOS_MS5611_OVERSAMPLING oversampling
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/* Glocal Variables */
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ConversionTypeTypeDef CurrentRead;
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/* Local Variables */
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MS5611CalibDataTypeDef CalibData;
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/* Straight from the datasheet */
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static uint32_t RawTemperature;
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static uint32_t RawPressure;
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static int64_t Pressure;
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static int64_t Temperature;
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static int32_t lastConversionStart;
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static int32_t PIOS_MS5611_Read(uint8_t address, uint8_t *buffer, uint8_t len);
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static int32_t PIOS_MS5611_WriteCommand(uint8_t command);
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// Second order temperature compensation. Temperature offset
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static int64_t compensation_t2;
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// Move into proper driver structure with cfg stored
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static uint32_t oversampling;
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static const struct pios_ms5611_cfg *dev_cfg;
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static int32_t i2c_id;
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/**
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* Initialise the MS5611 sensor
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*/
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int32_t ms5611_read_flag;
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void PIOS_MS5611_Init(const struct pios_ms5611_cfg *cfg, int32_t i2c_device)
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{
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i2c_id = i2c_device;
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oversampling = cfg->oversampling;
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dev_cfg = cfg; // Store cfg before enabling interrupt
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PIOS_MS5611_WriteCommand(MS5611_RESET);
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PIOS_DELAY_WaitmS(20);
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uint8_t data[2];
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// reset temperature compensation values
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compensation_t2 = 0;
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/* Calibration parameters */
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for (int i = 0; i < 6; i++) {
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PIOS_MS5611_Read(MS5611_CALIB_ADDR + i * 2, data, 2);
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CalibData.C[i] = (data[0] << 8) | data[1];
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}
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}
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/**
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* Start the ADC conversion
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* \param[in] PresOrTemp BMP085_PRES_ADDR or BMP085_TEMP_ADDR
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* \return 0 for success, -1 for failure (conversion completed and not read)
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*/
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int32_t PIOS_MS5611_StartADC(ConversionTypeTypeDef Type)
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{
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/* Start the conversion */
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if (Type == TemperatureConv) {
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while (PIOS_MS5611_WriteCommand(MS5611_TEMP_ADDR + oversampling) != 0) {
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continue;
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}
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} else if (Type == PressureConv) {
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while (PIOS_MS5611_WriteCommand(MS5611_PRES_ADDR + oversampling) != 0) {
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continue;
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}
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}
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lastConversionStart = PIOS_DELAY_GetRaw();
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CurrentRead = Type;
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return 0;
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}
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/**
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* @brief Return the delay for the current osr
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*/
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int32_t PIOS_MS5611_GetDelay()
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{
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switch (oversampling) {
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case MS5611_OSR_256:
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return 1;
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case MS5611_OSR_512:
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return 2;
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case MS5611_OSR_1024:
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return 3;
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case MS5611_OSR_2048:
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return 5;
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case MS5611_OSR_4096:
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return 10;
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default:
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break;
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}
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return 10;
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}
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/**
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* @brief Return the delay for the current osr in uS
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*/
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uint32_t PIOS_MS5611_GetDelayUs()
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{
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switch (oversampling) {
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case MS5611_OSR_256:
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return 600;
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case MS5611_OSR_512:
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return 1170;
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case MS5611_OSR_1024:
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return 2280;
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case MS5611_OSR_2048:
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return 4540;
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case MS5611_OSR_4096:
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return 9040;
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default:
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break;
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}
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return 10;
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}
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/**
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* Read the ADC conversion value (once ADC conversion has completed)
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* \return 0 if successfully read the ADC, -1 if failed
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*/
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int32_t PIOS_MS5611_ReadADC(void)
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{
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uint8_t Data[3];
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Data[0] = 0;
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Data[1] = 0;
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Data[2] = 0;
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while (PIOS_MS5611_GetDelayUs() > PIOS_DELAY_DiffuS(lastConversionStart)) {
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vTaskDelay(0);
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}
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static int64_t deltaTemp;
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/* Read and store the 16bit result */
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if (CurrentRead == TemperatureConv) {
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/* Read the temperature conversion */
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if (PIOS_MS5611_Read(MS5611_ADC_READ, Data, 3) != 0) {
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return -1;
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}
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RawTemperature = (Data[0] << 16) | (Data[1] << 8) | Data[2];
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// Difference between actual and reference temperature
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// dT = D2 - TREF = D2 - C5 * 2^8
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deltaTemp = ((int32_t)RawTemperature) - (CalibData.C[4] * POW2(8));
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// Actual temperature (-40…85°C with 0.01°C resolution)
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// TEMP = 20°C + dT * TEMPSENS = 2000 + dT * C6 / 2^23
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Temperature = 2000l + ((deltaTemp * CalibData.C[5]) / POW2(23));
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} else {
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int64_t Offset;
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int64_t Sens;
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// used for second order temperature compensation
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int64_t Offset2 = 0;
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int64_t Sens2 = 0;
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/* Read the pressure conversion */
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if (PIOS_MS5611_Read(MS5611_ADC_READ, Data, 3) != 0) {
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return -1;
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}
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// check if temperature is less than 20°C
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if (Temperature < 2000) {
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// Apply compensation
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// T2 = dT^2 / 2^31
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// OFF2 = 5 ⋅ (TEMP – 2000)^2/2
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// SENS2 = 5 ⋅ (TEMP – 2000)^2/2^2
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int64_t tcorr = (Temperature - 2000) * (Temperature - 2000);
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Offset2 = (5 * tcorr) / 2;
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Sens2 = (5 * tcorr) / 4;
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compensation_t2 = (deltaTemp * deltaTemp) >> 31;
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// Apply the "Very low temperature compensation" when temp is less than -15°C
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if (Temperature < -1500) {
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// OFF2 = OFF2 + 7 ⋅ (TEMP + 1500)^2
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// SENS2 = SENS2 + 11 ⋅ (TEMP + 1500)^2 / 2
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int64_t tcorr2 = (Temperature + 1500) * (Temperature + 1500);
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Offset2 += 7 * tcorr2;
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Sens2 += (11 * tcorr2) / 2;
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}
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} else {
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compensation_t2 = 0;
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Offset2 = 0;
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Sens2 = 0;
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}
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RawPressure = ((Data[0] << 16) | (Data[1] << 8) | Data[2]);
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// Offset at actual temperature
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// OFF = OFFT1 + TCO * dT = C2 * 2^16 + (C4 * dT) / 2^7
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Offset = ((int64_t)CalibData.C[1]) * POW2(16) + (((int64_t)CalibData.C[3]) * deltaTemp) / POW2(7) - Offset2;
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// Sensitivity at actual temperature
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// SENS = SENST1 + TCS * dT = C1 * 2^15 + (C3 * dT) / 2^8
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Sens = ((int64_t)CalibData.C[0]) * POW2(15) + (((int64_t)CalibData.C[2]) * deltaTemp) / POW2(8) - Sens2;
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// Temperature compensated pressure (10…1200mbar with 0.01mbar resolution)
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// P = D1 * SENS - OFF = (D1 * SENS / 2^21 - OFF) / 2^15
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Pressure = (((((int64_t)RawPressure) * Sens) / POW2(21)) - Offset) / POW2(15);
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}
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return 0;
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}
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/**
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* Return the most recently computed temperature in kPa
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*/
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float PIOS_MS5611_GetTemperature(void)
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{
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// Apply the second order low and very low temperature compensation offset
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return ((float)(Temperature - compensation_t2)) / 100.0f;
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}
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/**
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* Return the most recently computed pressure in kPa
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*/
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float PIOS_MS5611_GetPressure(void)
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{
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return ((float)Pressure) / 1000.0f;
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}
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/**
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* Reads one or more bytes into a buffer
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* \param[in] the command indicating the address to read
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* \param[out] buffer destination buffer
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* \param[in] len number of bytes which should be read
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* \return 0 if operation was successful
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* \return -1 if error during I2C transfer
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*/
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int32_t PIOS_MS5611_Read(uint8_t address, uint8_t *buffer, uint8_t len)
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{
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const struct pios_i2c_txn txn_list[] = {
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{
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.info = __func__,
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.addr = MS5611_I2C_ADDR,
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.rw = PIOS_I2C_TXN_WRITE,
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.len = 1,
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.buf = &address,
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}
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,
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{
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.info = __func__,
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.addr = MS5611_I2C_ADDR,
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.rw = PIOS_I2C_TXN_READ,
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.len = len,
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.buf = buffer,
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}
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};
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return PIOS_I2C_Transfer(i2c_id, txn_list, NELEMENTS(txn_list));
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}
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/**
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* Writes one or more bytes to the MS5611
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* \param[in] address Register address
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* \param[in] buffer source buffer
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* \return 0 if operation was successful
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* \return -1 if error during I2C transfer
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*/
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int32_t PIOS_MS5611_WriteCommand(uint8_t command)
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{
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const struct pios_i2c_txn txn_list[] = {
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{
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.info = __func__,
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.addr = MS5611_I2C_ADDR,
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.rw = PIOS_I2C_TXN_WRITE,
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.len = 1,
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.buf = &command,
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}
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,
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};
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return PIOS_I2C_Transfer(i2c_id, txn_list, NELEMENTS(txn_list));
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}
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/**
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* @brief Run self-test operation.
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* \return 0 if self-test succeed, -1 if failed
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*/
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int32_t PIOS_MS5611_Test()
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{
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// TODO: Is there a better way to test this than just checking that pressure/temperature has changed?
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int32_t cur_value = 0;
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cur_value = Temperature;
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PIOS_MS5611_StartADC(TemperatureConv);
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PIOS_DELAY_WaitmS(5);
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PIOS_MS5611_ReadADC();
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if (cur_value == Temperature) {
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return -1;
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}
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cur_value = Pressure;
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PIOS_MS5611_StartADC(PressureConv);
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PIOS_DELAY_WaitmS(26);
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PIOS_MS5611_ReadADC();
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if (cur_value == Pressure) {
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return -1;
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}
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return 0;
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}
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#endif /* PIOS_INCLUDE_MS5611 */
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/**
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* @}
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* @}
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*/
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