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eddys_snippets/I2Csensors/BMP280.c

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/*
* Copyright 2025 Edward V. Emelianov <edward.emelianoff@gmail.com>.
*
* 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/>.
*/
#include <stdio.h>
#include <usefull_macros.h>
#include "BMP280.h"
#include "i2c.h"
#include "sensors_private.h"
/**
* BMP280 registers
*/
#define BMP280_REG_HUM_LSB 0xFE
#define BMP280_REG_HUM_MSB 0xFD
#define BMP280_REG_HUM (BMP280_REG_HUM_MSB)
#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_ALLDATA (BMP280_REG_PRESS_MSB) // all data: P, T & H
#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_STATUS_MSRNG (1<<3) // measuring flag
#define BMP280_STATUS_UPDATE (1<<0) // update flag
#define BMP280_REG_CTRL_HUM 0xF2 /* bits: 2-0 osrs_h; */
#define BMP280_REG_RESET 0xE0
#define BMP280_RESET_VALUE 0xB6
#define BMP280_REG_ID 0xD0
#define BMP280_REG_CALIBA 0x88
#define BMP280_CALIBA_SIZE (26) // 26 bytes of calibration registers sequence from 0x88 to 0xa1
#define BMP280_CALIBB_SIZE (7) // 7 bytes of calibration registers sequence from 0xe1 to 0xe7
#define BMP280_REG_CALIB_H1 0xA1 // dig_H1
#define BMP280_REG_CALIBB 0xE1
#define BMP280_MODE_FORSED (1) // force single measurement
#define BMP280_MODE_NORMAL (3) // run continuosly
#define BMP280_CHIP_ID 0x58
#define BME280_CHIP_ID 0x60
typedef enum{ // K for filtering: next = [prev*(k-1) + data_ADC]/k
BMP280_FILTER_OFF = 0, // k=1, no filtering
BMP280_FILTER_2 = 1, // k=2, 2 samples to reach >75% of data_ADC
BMP280_FILTER_4 = 2, // k=4, 5 samples
BMP280_FILTER_8 = 3, // k=8, 11 samples
BMP280_FILTER_16 = 4, // k=16, 22 samples
} BMP280_Filter;
typedef enum{ // Number of oversampling
BMP280_NOMEASUR = 0,
BMP280_OVERS1 = 1,
BMP280_OVERS2 = 2,
BMP280_OVERS4 = 3,
BMP280_OVERS8 = 4,
BMP280_OVERS16 = 5,
} BMP280_Oversampling;
typedef struct{
BMP280_Filter filter; // filtering
BMP280_Oversampling p_os; // oversampling for pressure
BMP280_Oversampling t_os; // -//- temperature
BMP280_Oversampling h_os; // -//- humidity
uint8_t ID; // identificator
uint8_t regctl; // control register base value [(params.t_os << 5) | (params.p_os << 2)]
} BPM280_params_t;
// default parameters for initialized s->privdata
static const BPM280_params_t defparams = {
.filter = BMP280_FILTER_4,
.p_os = BMP280_OVERS16,
.t_os = BMP280_OVERS16,
.h_os = BMP280_OVERS16,
.ID = 0
};
typedef struct {
// temperature
uint16_t dig_T1; // 0x88 (LSB), 0x98 (MSB)
int16_t dig_T2; // ...
int16_t dig_T3;
// pressure
uint16_t dig_P1;
int16_t dig_P2;
int16_t dig_P3;
int16_t dig_P4;
int16_t dig_P5;
int16_t dig_P6;
int16_t dig_P7;
int16_t dig_P8;
int16_t dig_P9; // 0x9e, 0x9f
// humidity (partially calculated from EEE struct)
uint8_t unused; // 0xA0
uint8_t dig_H1; // 0xA1
int16_t dig_H2; // 0xE1...
uint8_t dig_H3; // only from EEE
uint16_t dig_H4;
uint16_t dig_H5;
int8_t dig_H6;
// calibration done
uint8_t calibrated;
// parameters
BPM280_params_t params;
} __attribute__ ((packed)) CaliData_t;
/*
// setters for `params`
void BMP280_setfilter(sensor_t *s, BMP280_Filter f){
((CaliData_t*)s->privdata)->params.filter = f;
}
void BMP280_setOSt(sensor_t *s, BMP280_Oversampling os){
((CaliData_t*)s->privdata)->params.t_os = os;
}
void BMP280_setOSp(sensor_t *s, BMP280_Oversampling os){
((CaliData_t*)s->privdata)->params.p_os = os;
}
void BMP280_setOSh(sensor_t *s, BMP280_Oversampling os){
((CaliData_t*)s->privdata)->params.h_os = os;
}*/
// get compensation data, return 1 if OK
static int readcompdata(sensor_t *s){
FNAME();
CaliData_t *CaliData = (CaliData_t*)s->privdata;
if(!i2c_read_data8(BMP280_REG_CALIBA, BMP280_CALIBA_SIZE, (uint8_t*)CaliData)){
DBG("Can't read calibration A data");
return FALSE;
}
if(CaliData->params.ID == BME280_CHIP_ID){
uint8_t EEE[BMP280_CALIBB_SIZE] = {0};
if(!i2c_read_reg8(BMP280_REG_CALIB_H1, &CaliData->dig_H1)){
WARNX("Can't read dig_H1");
return FALSE;
}
if(!i2c_read_data8(BMP280_REG_CALIBB, BMP280_CALIBB_SIZE, EEE)){
WARNX("Can't read rest of dig_Hx");
return FALSE;
}
// E5 is divided by two parts so we need this sex
CaliData->dig_H2 = (EEE[1] << 8) | EEE[0];
CaliData->dig_H3 = EEE[2];
CaliData->dig_H4 = (EEE[3] << 4) | (EEE[4] & 0x0f);
CaliData->dig_H5 = (EEE[5] << 4) | (EEE[4] >> 4);
CaliData->dig_H6 = EEE[6];
}
CaliData->calibrated = 1;
DBG("Calibration rdy");
return TRUE;
}
// do a soft-reset procedure
static int s_reset(){
if(!i2c_write_reg8(BMP280_REG_RESET, BMP280_RESET_VALUE)){
DBG("Can't reset\n");
return FALSE;
}
return TRUE;
}
// read compensation data & write registers
static int s_init(sensor_t *s){
s->status = SENS_NOTINIT;
uint8_t devid;
if(!i2c_read_reg8(BMP280_REG_ID, &devid)){
DBG("Can't read BMP280_REG_ID");
return FALSE;
}
DBG("Got device ID: 0x%02x", devid);
if(devid != BMP280_CHIP_ID && devid != BME280_CHIP_ID){
WARNX("Not BM[P/E]280\n");
return FALSE;
}
if(!s_reset()) return FALSE;
// wait whlie update done
uint8_t reg = BMP280_STATUS_UPDATE;
while(reg & BMP280_STATUS_UPDATE){ // wait while update is done
if(!i2c_read_reg8(BMP280_REG_STATUS, &reg)){
DBG("Can't read status");
return FALSE;
}
}
// allocate calibration and other data if need
if(!s->privdata){
s->privdata = calloc(1, sizeof(CaliData_t));
((CaliData_t*)s->privdata)->params = defparams; // and init default parameters
DBG("ALLOCA");
}else ((CaliData_t*)s->privdata)->calibrated = 0;
BPM280_params_t *params = &((CaliData_t*)s->privdata)->params;
params->ID = devid;
if(!readcompdata(s)){
DBG("Can't read calibration data\n");
return FALSE;
}else{
#ifdef EBUG
CaliData_t *CaliData = (CaliData_t*)s->privdata;
DBG("T: %d, %d, %d", CaliData->dig_T1, CaliData->dig_T2, CaliData->dig_T3);
DBG("\P: %d, %d, %d, %d, %d, %d, %d, %d, %d", CaliData->dig_P1, CaliData->dig_P2, CaliData->dig_P3,
CaliData->dig_P4, CaliData->dig_P5, CaliData->dig_P6, CaliData->dig_P7, CaliData->dig_P8, CaliData->dig_P9);
if(devid == BME280_CHIP_ID){ // H compensation
DBG("H: %d, %d, %d, %d, %d, %d", CaliData->dig_H1, CaliData->dig_H2, CaliData->dig_H3,
CaliData->dig_H4, CaliData->dig_H5, CaliData->dig_H6);
}
#endif
}
// write filter configuration
reg = params->filter << 2;
if(!i2c_write_reg8(BMP280_REG_CONFIG, reg)){
DBG("Can't save filter settings\n");
return FALSE;
}
reg = (params->t_os << 5) | (params->p_os << 2); // oversampling for P/T, sleep mode
if(!i2c_write_reg8(BMP280_REG_CTRL, reg)){
DBG("Can't write settings for P/T\n");
return FALSE;
}
params->regctl = reg;
if(devid == BME280_CHIP_ID){ // write CTRL_HUM only AFTER CTRL!
reg = params->h_os;
if(!i2c_write_reg8(BMP280_REG_CTRL_HUM, reg)){
DBG("Can't write settings for H\n");
return FALSE;
}
}
DBG("OK, inited");
s->status = SENS_RELAX;
return TRUE;
}
// start measurement, @return 1 if all OK
static int s_start(sensor_t *s){
if(!s->privdata || s->status == SENS_BUSY || ((CaliData_t*)s->privdata)->calibrated == 0) return FALSE;
uint8_t reg = ((CaliData_t*)s->privdata)->params.regctl | BMP280_MODE_FORSED; // start single measurement
if(!i2c_write_reg8(BMP280_REG_CTRL, reg)){
DBG("Can't write CTRL reg\n");
return FALSE;
}
s->status = SENS_BUSY;
return TRUE;
}
// return T in degC
static inline float compTemp(sensor_t *s, int32_t adc_temp, int32_t *t_fine){
CaliData_t *CaliData = (CaliData_t*)s->privdata;
int32_t var1, var2;
var1 = ((((adc_temp >> 3) - ((int32_t) CaliData->dig_T1 << 1)))
* (int32_t) CaliData->dig_T2) >> 11;
var2 = (((((adc_temp >> 4) - (int32_t) CaliData->dig_T1)
* ((adc_temp >> 4) - (int32_t) CaliData->dig_T1)) >> 12)
* (int32_t) CaliData->dig_T3) >> 14;
*t_fine = var1 + var2;
return ((*t_fine * 5 + 128) >> 8) / 100.;
}
// return P in Pa
static inline double compPres(sensor_t *s, int32_t adc_press, int32_t fine_temp){
CaliData_t *CaliData = (CaliData_t*)s->privdata;
int64_t var1, var2, p;
var1 = (int64_t) fine_temp - 128000;
var2 = var1 * var1 * (int64_t) CaliData->dig_P6;
var2 = var2 + ((var1 * (int64_t) CaliData->dig_P5) << 17);
var2 = var2 + (((int64_t) CaliData->dig_P4) << 35);
var1 = ((var1 * var1 * (int64_t) CaliData->dig_P3) >> 8)
+ ((var1 * (int64_t) CaliData->dig_P2) << 12);
var1 = (((int64_t) 1 << 47) + var1) * ((int64_t) CaliData->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) CaliData->dig_P9 * (p >> 13) * (p >> 13)) >> 25;
var2 = ((int64_t) CaliData->dig_P8 * p) >> 19;
p = ((p + var1 + var2) >> 8) + ((int64_t) CaliData->dig_P7 << 4);
return p/25600.; // hPa
}
// return H in percents
static inline double compHum(sensor_t *s, int32_t adc_hum, int32_t fine_temp){
CaliData_t *CaliData = (CaliData_t*)s->privdata;
int32_t v_x1_u32r;
v_x1_u32r = fine_temp - (int32_t) 76800;
v_x1_u32r = ((((adc_hum << 14) - (((int32_t)CaliData->dig_H4) << 20)
- (((int32_t)CaliData->dig_H5) * v_x1_u32r)) + (int32_t)16384) >> 15)
* (((((((v_x1_u32r * ((int32_t)CaliData->dig_H6)) >> 10)
* (((v_x1_u32r * ((int32_t)CaliData->dig_H3)) >> 11)
+ (int32_t)32768)) >> 10) + (int32_t)2097152)
* ((int32_t)CaliData->dig_H2) + 8192) >> 14);
v_x1_u32r = v_x1_u32r
- (((((v_x1_u32r >> 15) * (v_x1_u32r >> 15)) >> 7)
* ((int32_t)CaliData->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)/1024.;
}
static sensor_status_t s_process(sensor_t *s){
uint8_t reg;
if(s->status != SENS_BUSY) goto ret;
if(!i2c_read_reg8(BMP280_REG_STATUS, &reg)) return (s->status = SENS_ERR);
DBG("stat=0x%02X", reg);
if(reg & BMP280_STATUS_MSRNG) goto ret;
// OK, measurements done -> get and calculate data
CaliData_t *CaliData = (CaliData_t*)s->privdata;
uint8_t ID = CaliData->params.ID;
uint8_t datasz = 8; // amount of bytes to read
uint8_t data[8];
if(ID == BMP280_CHIP_ID) datasz = 6; // no humidity
if(!i2c_read_data8(BMP280_REG_ALLDATA, datasz, data)){
DBG("Can't read data");
return (s->status = SENS_ERR);
}
int32_t p = (data[0] << 12) | (data[1] << 4) | (data[2] >> 4);
DBG("puncomp = %d", p);
int32_t t = (data[3] << 12) | (data[4] << 4) | (data[5] >> 4);
DBG("tuncomp = %d", t);
int32_t t_fine;
s->data.T = compTemp(s, t, &t_fine);
DBG("tfine = %d", t_fine);
s->data.P = compPres(s, p, t_fine);
if(ID == BME280_CHIP_ID){
int32_t h = (data[6] << 8) | data[7];
DBG("huncomp = %d", h);
s->data.H = compHum(s, h, t_fine);
}
s->status = SENS_RDY;
ret:
return s->status;
}
static sensor_props_t s_props(sensor_t *s){
sensor_props_t p = {.T = 1, .P = 1};
if(s && s->privdata){
if(((CaliData_t*)s->privdata)->params.ID == BME280_CHIP_ID) p.H = 1;
}
return p;
}
static int s_heater(sensor_t _U_ *s, int _U_ on){
return FALSE;
}
sensor_t BMP280 = {
.name = "BMP280",
.address = 0x76,
.status = SENS_NOTINIT,
.init = s_init,
.start = s_start,
.heater = s_heater,
.process = s_process,
.properties = s_props,
};
sensor_t BME280 = {
.name = "BME280",
.address = 0x76,
.status = SENS_NOTINIT,
.init = s_init,
.start = s_start,
.heater = s_heater,
.process = s_process,
.properties = s_props,
};
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