/**
* The MIT License (MIT)
*
* Copyright (c) 2016 sheinz (https://github.com/sheinz)
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include <stddef.h>
#include "bmp280.h"
#include "i2c/i2c.h"
#ifdef BMP280_DEBUG
#include <stdio.h>
#define debug(fmt, ...) printf("%s" fmt "\n", "bmp280: ", ## __VA_ARGS__);
#else
#define debug(fmt, ...)
#endif
/**
* BMP280 registers
*/
#define BMP280_REG_TEMP_XLSB 0xFC /* bits: 7-4 */
#define BMP280_REG_TEMP_LSB 0xFB
#define BMP280_REG_TEMP_MSB 0xFA
#define BMP280_REG_TEMP (BMP280_REG_TEMP_MSB)
#define BMP280_REG_PRESS_XLSB 0xF9 /* bits: 7-4 */
#define BMP280_REG_PRESS_LSB 0xF8
#define BMP280_REG_PRESS_MSB 0xF7
#define BMP280_REG_PRESSURE (BMP280_REG_PRESS_MSB)
#define BMP280_REG_CONFIG 0xF5 /* bits: 7-5 t_sb; 4-2 filter; 0 spi3w_en */
#define BMP280_REG_CTRL 0xF4 /* bits: 7-5 osrs_t; 4-2 osrs_p; 1-0 mode */
#define BMP280_REG_STATUS 0xF3 /* bits: 3 measuring; 0 im_update */
#define BMP280_REG_CTRL_HUM 0xF2 /* bits: 2-0 osrs_h; */
#define BMP280_REG_RESET 0xE0
#define BMP280_REG_ID 0xD0
#define BMP280_REG_CALIB 0x88
#define BMP280_REG_HUM_CALIB 0x88
#define BMP280_RESET_VALUE 0xB6
void bmp280_init_default_params(bmp280_params_t *params)
{
params->mode = BMP280_MODE_NORMAL;
params->filter = BMP280_FILTER_OFF;
params->oversampling = BMP280_STANDARD;
params->oversampling_humidity = BMP280_STANDARD;
params->standby = BMP280_STANDBY_250;
}
static bool read_register16(uint8_t i2c_addr, uint8_t addr, uint16_t *value)
{
uint8_t d[] = {0, 0};
if (i2c_slave_read(i2c_addr, addr, d, sizeof(d))) {
*value = d[0] | (d[1] << 8);
return true;
}
return false;
}
static bool read_calibration_data(bmp280_t *dev)
{
uint8_t i2c_addr = dev->i2c_addr;
if (read_register16(i2c_addr, 0x88, &dev->dig_T1) &&
read_register16(i2c_addr, 0x8a, (uint16_t *)&dev->dig_T2) &&
read_register16(i2c_addr, 0x8c, (uint16_t *)&dev->dig_T3) &&
read_register16(i2c_addr, 0x8e, &dev->dig_P1) &&
read_register16(i2c_addr, 0x90, (uint16_t *)&dev->dig_P2) &&
read_register16(i2c_addr, 0x92, (uint16_t *)&dev->dig_P3) &&
read_register16(i2c_addr, 0x94, (uint16_t *)&dev->dig_P4) &&
read_register16(i2c_addr, 0x96, (uint16_t *)&dev->dig_P5) &&
read_register16(i2c_addr, 0x98, (uint16_t *)&dev->dig_P6) &&
read_register16(i2c_addr, 0x9a, (uint16_t *)&dev->dig_P7) &&
read_register16(i2c_addr, 0x9c, (uint16_t *)&dev->dig_P8) &&
read_register16(i2c_addr, 0x9e, (uint16_t *)&dev->dig_P9)) {
debug("Calibration data received:");
debug("dig_T1=%d", dev->dig_T1);
debug("dig_T2=%d", dev->dig_T2);
debug("dig_T3=%d", dev->dig_T3);
debug("dig_P1=%d", dev->dig_P1);
debug("dig_P2=%d", dev->dig_P2);
debug("dig_P3=%d", dev->dig_P3);
debug("dig_P4=%d", dev->dig_P4);
debug("dig_P5=%d", dev->dig_P5);
debug("dig_P6=%d", dev->dig_P6);
debug("dig_P7=%d", dev->dig_P7);
debug("dig_P8=%d", dev->dig_P8);
debug("dig_P9=%d", dev->dig_P9);
return true;
}
return false;
}
static bool read_hum_calibration_data(bmp280_t *dev)
{
uint8_t i2c_addr = dev->i2c_addr;
uint16_t h4, h5;
if (i2c_slave_read(i2c_addr, 0xa1, &dev->dig_H1, 1) &&
read_register16(i2c_addr, 0xe1, (uint16_t *)&dev->dig_H2) &&
i2c_slave_read(i2c_addr, 0xe3, &dev->dig_H3, 1) &&
read_register16(i2c_addr, 0xe4, &h4) &&
read_register16(i2c_addr, 0xe5, &h5) &&
i2c_slave_read(i2c_addr, 0xe7, (uint8_t *)&dev->dig_H6, 1)) {
dev->dig_H4 = (h4 & 0x00ff) << 4 | (h4 & 0x0f00) >> 8;
dev->dig_H5 = h5 >> 4;
debug("Calibration data received:");
debug("dig_H1=%d", dev->dig_H1);
debug("dig_H2=%d", dev->dig_H2);
debug("dig_H3=%d", dev->dig_H3);
debug("dig_H4=%d", dev->dig_H4);
debug("dig_H5=%d", dev->dig_H5);
debug("dig_H6=%d", dev->dig_H6);
return true;
}
return false;
}
static bool write_register8(uint8_t i2c_addr, uint8_t addr, uint8_t value)
{
uint8_t d[] = {addr, value};
return i2c_slave_write(i2c_addr, d, 2);
}
bool bmp280_init(bmp280_t *dev, bmp280_params_t *params)
{
uint8_t i2c_addr = dev->i2c_addr;
if (i2c_addr != BMP280_I2C_ADDRESS_0 && i2c_addr != BMP280_I2C_ADDRESS_1) {
debug("Invalid I2C address");
return false;
}
if (!i2c_slave_read(i2c_addr, BMP280_REG_ID, &dev->id, 1)) {
debug("Sensor not found");
return false;
}
if (dev->id != BMP280_CHIP_ID && dev->id != BME280_CHIP_ID) {
debug("Sensor wrong version");
return false;
}
// Soft reset.
if (!write_register8(i2c_addr, BMP280_REG_RESET, BMP280_RESET_VALUE)) {
debug("Failed resetting sensor");
return false;
}
// Wait until finished copying over the NVP data.
while (1) {
uint8_t status;
if (i2c_slave_read(i2c_addr, BMP280_REG_STATUS, &status, 1) && (status & 1) == 0)
break;
}
if (!read_calibration_data(dev)) {
debug("Failed to read calibration data");
return false;
}
if (dev->id == BME280_CHIP_ID && !read_hum_calibration_data(dev)) {
debug("Failed to read humidity calibration data");
return false;
}
uint8_t config = (params->standby << 5) | (params->filter << 2);
debug("Writing config reg=%x", config);
if (!write_register8(i2c_addr, BMP280_REG_CONFIG, config)) {
debug("Failed configuring sensor");
return false;
}
uint8_t oversampling_temp =
(params->oversampling == BMP280_ULTRA_HIGH_RES) ? 2 : 1;
if (params->mode == BMP280_MODE_FORCED) {
params->mode = BMP280_MODE_SLEEP; // initial mode for forced is sleep
}
uint8_t ctrl = (oversampling_temp << 5) | (params->oversampling << 2)
| (params->mode);
if (dev->id == BME280_CHIP_ID) {
// Write crtl hum reg first, only active after write to BMP280_REG_CTRL.
uint8_t ctrl_hum = params->oversampling_humidity;
debug("Writing ctrl hum reg=%x", ctrl_hum);
if (!write_register8(i2c_addr, BMP280_REG_CTRL_HUM, ctrl_hum)) {
debug("Failed controlling sensor");
return false;
}
}
debug("Writing ctrl reg=%x", ctrl);
if (!write_register8(i2c_addr, BMP280_REG_CTRL, ctrl)) {
debug("Failed controlling sensor");
return false;
}
return true;
}
bool bmp280_force_measurement(bmp280_t *dev)
{
uint8_t ctrl;
if (!i2c_slave_read(dev->i2c_addr, BMP280_REG_CTRL, &ctrl, 1))
return false;
ctrl &= ~0b11; // clear two lower bits
ctrl |= BMP280_MODE_FORCED;
debug("Writing ctrl reg=%x", ctrl);
if (!write_register8(dev->i2c_addr, BMP280_REG_CTRL, ctrl)) {
debug("Failed starting forced mode");
return false;
}
return true;
}
bool bmp280_is_measuring(bmp280_t *dev)
{
uint8_t status;
if (!i2c_slave_read(dev->i2c_addr, BMP280_REG_STATUS, &status, 1))
return false;
if (status & (1 << 3)) {
debug("Status: measuring");
return true;
}
debug("Status: idle");
return false;
}
/**
* Compensation algorithm is taken from BMP280 datasheet.
*
* Return value is in degrees Celsius.
*/
static inline int32_t compensate_temperature(bmp280_t *dev,
int32_t adc_temp, int32_t *fine_temp)
{
int32_t var1, var2;
var1 = ((((adc_temp >> 3) - ((int32_t)dev->dig_T1 << 1)))
* (int32_t)dev->dig_T2) >> 11;
var2 = (((((adc_temp >> 4) - (int32_t)dev->dig_T1)
* ((adc_temp >> 4) - (int32_t)dev->dig_T1)) >> 12)
* (int32_t)dev->dig_T3) >> 14;
*fine_temp = var1 + var2;
return (*fine_temp * 5 + 128) >> 8;
}
/**
* Compensation algorithm is taken from BMP280 datasheet.
*
* Return value is in Pa, 24 integer bits and 8 fractional bits.
*/
static inline uint32_t compensate_pressure(bmp280_t *dev,
int32_t adc_press, int32_t fine_temp)
{
int64_t var1, var2, p;
var1 = (int64_t)fine_temp - 128000;
var2 = var1 * var1 * (int64_t)dev->dig_P6;
var2 = var2 + ((var1 * (int64_t)dev->dig_P5) << 17);
var2 = var2 + (((int64_t)dev->dig_P4) << 35);
var1 = ((var1 * var1 * (int64_t)dev->dig_P3) >> 8) +
((var1 * (int64_t)dev->dig_P2) << 12);
var1 = (((int64_t)1 << 47) + var1) * ((int64_t)dev->dig_P1) >> 33;
if (var1 == 0) {
return 0; // avoid exception caused by division by zero
}
p = 1048576 - adc_press;
p = (((p << 31) - var2) * 3125) / var1;
var1 = ((int64_t)dev->dig_P9 * (p >> 13) * (p >> 13)) >> 25;
var2 = ((int64_t)dev->dig_P8 * p) >> 19;
p = ((p + var1 + var2) >> 8) + ((int64_t)dev->dig_P7 << 4);
return p;
}
/**
* Compensation algorithm is taken from BME280 datasheet.
*
* Return value is in Pa, 24 integer bits and 8 fractional bits.
*/
static inline uint32_t compensate_humidity(bmp280_t *dev,
int32_t adc_hum, int32_t fine_temp)
{
int32_t v_x1_u32r;
v_x1_u32r = fine_temp - (int32_t)76800;
v_x1_u32r = ((((adc_hum << 14) - ((int32_t)dev->dig_H4 << 20) -
((int32_t)dev->dig_H5 * v_x1_u32r)) +
(int32_t)16384) >> 15) *
(((((((v_x1_u32r * (int32_t)dev->dig_H6) >> 10) *
(((v_x1_u32r * (int32_t)dev->dig_H3) >> 11) +
(int32_t)32768)) >> 10) + (int32_t)2097152) *
(int32_t)dev->dig_H2 + 8192) >> 14);
v_x1_u32r = v_x1_u32r - (((((v_x1_u32r >> 15) * (v_x1_u32r >> 15)) >> 7) *
(int32_t)dev->dig_H1) >> 4);
v_x1_u32r = v_x1_u32r < 0 ? 0 : v_x1_u32r;
v_x1_u32r = v_x1_u32r > 419430400 ? 419430400 : v_x1_u32r;
return v_x1_u32r >> 12;
}
bool bmp280_read_fixed(bmp280_t *dev, int32_t *temperature,
uint32_t *pressure, uint32_t *humidity)
{
int32_t adc_pressure;
int32_t adc_temp;
uint8_t data[8];
// Only the BME280 supports reading the humidity.
if (dev->id != BME280_CHIP_ID) {
if (humidity)
*humidity = 0;
humidity = NULL;
}
// Need to read in one sequence to ensure they match.
size_t size = humidity ? 8 : 6;
if (!i2c_slave_read(dev->i2c_addr, 0xf7, data, size)) {
debug("Failed reading");
return false;
}
adc_pressure = data[0] << 12 | data[1] << 4 | data[2] >> 4;
adc_temp = data[3] << 12 | data[4] << 4 | data[5] >> 4;
debug("ADC temperature: %d", adc_temp);
debug("ADC pressure: %d", adc_pressure);
int32_t fine_temp;
*temperature = compensate_temperature(dev, adc_temp, &fine_temp);
*pressure = compensate_pressure(dev, adc_pressure, fine_temp);
if (humidity) {
int32_t adc_humidity = data[6] << 8 | data[7];
debug("ADC humidity: %d", adc_humidity);
*humidity = compensate_humidity(dev, adc_humidity, fine_temp);
}
return true;
}
bool bmp280_read_float(bmp280_t *dev, float *temperature,
float *pressure, float *humidity)
{
int32_t fixed_temperature;
uint32_t fixed_pressure;
uint32_t fixed_humidity;
if (bmp280_read_fixed(dev, &fixed_temperature, &fixed_pressure,
humidity ? &fixed_humidity : NULL)) {
*temperature = (float)fixed_temperature/100;
*pressure = (float)fixed_pressure/256;
if (humidity)
*humidity = (float)fixed_humidity/1024;
return true;
}
return false;
}