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/*
* spreadspace avr utils
*
*
* Copyright (C) 2016 Bernhard Tittelbach <bernhard@tittelbach.org>
* Thanks to Adafruit for writing a great example. Go buy their stuff!
*
* This file is part of spreadspace avr utils.
*
* spreadspace avr utils 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
* any later version.
*
* spreadspace avr utils 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 spreadspace avr utils. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdio.h>
#include <avr/pgmspace.h>
#include <LUFA/Drivers/Peripheral/SPI.h>
#include "bmp280.h"
void bmp280_cs(bmp280_sensor *sensor, uint8_t select)
{
if (!select)
*(sensor->cs_port) |= _BV(sensor->cs_pin);
else
*(sensor->cs_port) &= ~ _BV(sensor->cs_pin);
}
void bmp280_write8(bmp280_sensor *sensor, uint8_t reg, uint8_t value)
{
bmp280_cs(sensor, true);
SPI_SendByte(reg & ~0x80); //bit 7 needs to be low for write mode
SPI_SendByte(value);
bmp280_cs(sensor, false);
}
uint8_t bmp280_read8(bmp280_sensor *sensor, uint8_t reg)
{
bmp280_cs(sensor, true);
SPI_SendByte(reg | 0x80); //bit 7 high for read mode
uint8_t value = SPI_ReceiveByte();
bmp280_cs(sensor, false);
return value;
}
uint16_t bmp280_read16(bmp280_sensor *sensor, uint8_t reg)
{
uint16_t value = 0;
bmp280_cs(sensor, true);
SPI_SendByte(reg | 0x80); //bit 7 high for read mode
value |= ((uint16_t) SPI_ReceiveByte() & 0xFF) << 8;
value |= (uint16_t) SPI_ReceiveByte() & 0xFF;
bmp280_cs(sensor, false);
return value;
}
uint32_t bmp280_read24(bmp280_sensor *sensor, uint8_t reg)
{
uint32_t value = 0;
bmp280_cs(sensor, true);
SPI_SendByte(reg | 0x80); //bit 7 high for read mode
value |= ((uint32_t) SPI_ReceiveByte() & 0xFF) << 16;
value |= ((uint32_t) SPI_ReceiveByte() & 0xFF) << 8;
value |= (uint32_t) SPI_ReceiveByte() & 0xFF;
bmp280_cs(sensor, false);
return value;
}
int16_t bmp280_readS16(bmp280_sensor *sensor, uint8_t reg)
{
return (int16_t) bmp280_read16(sensor, reg);
}
uint16_t bmp280_read16_LE(bmp280_sensor *sensor, uint8_t reg)
{
uint16_t value = bmp280_read16(sensor, reg);
return (value >> 8) | (value << 8);
}
int16_t bmp280_readS16_LE(bmp280_sensor *sensor, uint8_t reg)
{
return (int16_t)bmp280_read16_LE(sensor, reg);
}
void bmp280_readCoefficients(bmp280_sensor *sensor)
{
sensor->dig_T1 = bmp280_read16_LE(sensor,BMP280_REGISTER_DIG_T1);
sensor->dig_T2 = bmp280_readS16_LE(sensor,BMP280_REGISTER_DIG_T2);
sensor->dig_T3 = bmp280_readS16_LE(sensor,BMP280_REGISTER_DIG_T3);
sensor->dig_P1 = bmp280_read16_LE(sensor,BMP280_REGISTER_DIG_P1);
sensor->dig_P2 = bmp280_readS16_LE(sensor,BMP280_REGISTER_DIG_P2);
sensor->dig_P3 = bmp280_readS16_LE(sensor,BMP280_REGISTER_DIG_P3);
sensor->dig_P4 = bmp280_readS16_LE(sensor,BMP280_REGISTER_DIG_P4);
sensor->dig_P5 = bmp280_readS16_LE(sensor,BMP280_REGISTER_DIG_P5);
sensor->dig_P6 = bmp280_readS16_LE(sensor,BMP280_REGISTER_DIG_P6);
sensor->dig_P7 = bmp280_readS16_LE(sensor,BMP280_REGISTER_DIG_P7);
sensor->dig_P8 = bmp280_readS16_LE(sensor,BMP280_REGISTER_DIG_P8);
sensor->dig_P9 = bmp280_readS16_LE(sensor,BMP280_REGISTER_DIG_P9);
}
uint8_t bmp280_check_chipid(bmp280_sensor *sensor)
{
uint8_t chip_id = bmp280_read8(sensor, BMP280_REGISTER_CHIPID);
return chip_id == 0x58;
}
//need to init SPI beforehand
uint8_t bmp280_init(bmp280_sensor *sensor, volatile uint8_t *cs_port, uint8_t cs_pin)
{
memset(sensor,0,sizeof(bmp280_sensor));
sensor->cs_port = cs_port;
sensor->cs_pin = cs_pin;
uint8_t sensor_available = bmp280_check_chipid(sensor);
if (!sensor_available)
return sensor_available; //don't talk with chip, it doesn't speak our language
bmp280_readCoefficients(sensor);
bmp280_write8(sensor, BMP280_REGISTER_CONTROL, 0x3F);
return sensor_available;
}
int32_t bmp280_readFineTemp(bmp280_sensor *sensor)
{
int32_t var1, var2;
int32_t adc_T = bmp280_read24(sensor, BMP280_REGISTER_TEMPDATA);
adc_T >>= 4;
var1 = ((((adc_T>>3) - ((int32_t)sensor->dig_T1 <<1))) * ((int32_t)sensor->dig_T2)) >> 11;
var2 = (((((adc_T>>4) - ((int32_t)sensor->dig_T1)) * ((adc_T>>4) - ((int32_t)sensor->dig_T1))) >> 12) * ((int32_t)sensor->dig_T3)) >> 14;
return var1 + var2;
}
float bmp280_convertTempToCelsius(int32_t bmp280_t_fine)
{
float T = (bmp280_t_fine * 5 + 128) >> 8;
return T/100;
}
float bmp280_readTemp(bmp280_sensor *sensor)
{
return bmp280_convertTempToCelsius(bmp280_readFineTemp(sensor));
}
bmp280_result bmp280_readTempAndPressure(bmp280_sensor *sensor)
{
bmp280_result result;
result.temperature = 0;
result.pressure = 0;
int64_t var1, var2, p;
int32_t bmp280_t_fine = bmp280_readFineTemp(sensor);
result.temperature = bmp280_convertTempToCelsius(bmp280_t_fine);
int32_t adc_P = bmp280_read24(sensor, BMP280_REGISTER_PRESSUREDATA);
adc_P >>= 4;
var1 = ((int64_t)bmp280_t_fine) - 128000;
var2 = var1 * var1 * (int64_t)sensor->dig_P6;
var2 = var2 + ((var1*(int64_t)sensor->dig_P5)<<17);
var2 = var2 + (((int64_t)sensor->dig_P4)<<35);
var1 = ((var1 * var1 * (int64_t)sensor->dig_P3)>>8) +
((var1 * (int64_t)sensor->dig_P2)<<12);
var1 = (((((int64_t)1)<<47)+var1))*((int64_t)sensor->dig_P1)>>33;
if (var1 == 0)
{
return result; // avoid exception caused by division by zero
}
p = 1048576 - adc_P;
p = (((p<<31) - var2)*3125) / var1;
var1 = (((int64_t)sensor->dig_P9) * (p>>13) * (p>>13)) >> 25;
var2 = (((int64_t)sensor->dig_P8) * p) >> 19;
p = ((p + var1 + var2) >> 8) + (((int64_t)sensor->dig_P7)<<4);
result.pressure = (float)p/256;
return result;
}
float bmp280_readPressure(bmp280_sensor *sensor)
{
bmp280_result result = bmp280_readTempAndPressure(sensor);
return result.pressure;
}
float bmp280_calcAltitude(float pressure, float sealevelp)
{
pressure /= 100;
return 44330 * (1.0 - pow(pressure / sealevelp, 0.1903));
}
float bmp280_readAltitude(bmp280_sensor *sensor, float sealevelp)
{
return bmp280_calcAltitude(bmp280_readTempAndPressure(sensor).pressure, sealevelp);
}
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