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BME280 support.

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The BME280 is close to compatible with the existing BMP280 and extends it with support for measuring humidity, so support has been bundled into the bmp280 driver.

The example now auto-detects the device and displays the humidity for the BME280.

The I2C bus initialization has been moved out of the bmp280 driver to support multiple devices.

The check-id and reset logic has been bundled into the driver initialization. It needs to be re-initialized after reset anyway and the chip-id is need to initialize it, just re-initialize to reset.

Support has been added for multiple devices. The calibration data storage needs to be managed by the caller rather than static data. The caller can choose the I2C address to allow two BMx280 devices to be used on the same I2C bus.

An interface has been added to return the measurement values in an integer fixed float format. The float format interface is still there.

All the values are read in one I2C transaction to ensure they are a consistent set.

Renamed bmp280_calib_t to bmp280_t, and removed read_register8.
This commit is contained in:
ourairquality 2016-08-15 15:36:09 +10:00
parent b07c34b863
commit f0c43ff5d5
4 changed files with 369 additions and 179 deletions
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49
examples/bmp280/bmp280_example.c
View file

@ -6,43 +6,55 @@
#include "FreeRTOS.h"
#include "task.h"
#include "i2c/i2c.h"
#include "bmp280/bmp280.h"
// In forced mode user initiate measurement each time.
// In normal mode measurement is done continuously with specified standby time.
// #define MODE_FORCED
const uint8_t scl_pin = 5;
const uint8_t sda_pin = 4;
const uint8_t scl_pin = 0;
const uint8_t sda_pin = 2;
#ifdef MODE_FORCED
static void bmp280_task_forced(void *pvParameters)
{
bmp280_params_t params;
float pressure, temperature;
float pressure, temperature, humidity;
bmp280_init_default_params(&params);
params.mode = BMP280_MODE_FORCED;
bmp280_t bmp280_dev;
bmp280_dev.i2c_addr = BMP280_I2C_ADDRESS_0;
while (1) {
while (!bmp280_init(&params, scl_pin, sda_pin)) {
while (!bmp280_init(&bmp280_dev, &params)) {
printf("BMP280 initialization failed\n");
vTaskDelay(1000 / portTICK_RATE_MS);
}
bool bme280p = bmp280_dev.id == BME280_CHIP_ID;
printf("BMP280: found %s\n", bme280p ? "BME280" : "BMP280");
while(1) {
vTaskDelay(1000 / portTICK_RATE_MS);
if (!bmp280_force_measurement()) {
if (!bmp280_force_measurement(&bmp280_dev)) {
printf("Failed initiating measurement\n");
break;
}
while (bmp280_is_measuring()) {}; // wait for measurement to complete
// wait for measurement to complete
while (bmp280_is_measuring(&bmp280_dev)) {};
if (!bmp280_read(&temperature, &pressure)) {
if (!bmp280_read_float(&bmp280_dev, &temperature, &pressure, &humidity)) {
printf("Temperature/pressure reading failed\n");
break;
}
printf("Pressure: %.2f Pa, Temperature: %.2f C\n", pressure, temperature);
printf("Pressure: %.2f Pa, Temperature: %.2f C", pressure, temperature);
if (bme280p)
printf(", Humidity: %.2f\n", humidity);
else
printf("\n");
}
}
}
@ -50,22 +62,33 @@ static void bmp280_task_forced(void *pvParameters)
static void bmp280_task_normal(void *pvParameters)
{
bmp280_params_t params;
float pressure, temperature;
float pressure, temperature, humidity;
bmp280_init_default_params(&params);
bmp280_t bmp280_dev;
bmp280_dev.i2c_addr = BMP280_I2C_ADDRESS_0;
while (1) {
while (!bmp280_init(&params, scl_pin, sda_pin)) {
while (!bmp280_init(&bmp280_dev, &params)) {
printf("BMP280 initialization failed\n");
vTaskDelay(1000 / portTICK_RATE_MS);
}
bool bme280p = bmp280_dev.id == BME280_CHIP_ID;
printf("BMP280: found %s\n", bme280p ? "BME280" : "BMP280");
while(1) {
vTaskDelay(1000 / portTICK_RATE_MS);
if (!bmp280_read(&temperature, &pressure)) {
if (!bmp280_read_float(&bmp280_dev, &temperature, &pressure, &humidity)) {
printf("Temperature/pressure reading failed\n");
break;
}
printf("Pressure: %.2f Pa, Temperature: %.2f C\n", pressure, temperature);
printf("Pressure: %.2f Pa, Temperature: %.2f C", pressure, temperature);
if (bme280p)
printf(", Humidity: %.2f\n", humidity);
else
printf("\n");
}
}
}
@ -80,6 +103,8 @@ void user_init(void)
printf("SDK version : %s\n", sdk_system_get_sdk_version());
printf("GIT version : %s\n", GITSHORTREV);
i2c_init(scl_pin, sda_pin);
#ifdef MODE_FORCED
xTaskCreate(bmp280_task_forced, (signed char *)"bmp280_task", 256, NULL, 2, NULL);
#else

67
extras/bmp280/README.md
View file

@ -1,10 +1,10 @@
# Driver for BMP280 absolute barometric pressure sensor
# Driver for BMP280 and BME280 absolute barometric pressure sensors
The driver works only with BMP280 sensor. For BMP080/BMP180 there's a separate
driver. Even though BMP280 is a successor of BMP180 they are not compatible.
They have different registers and different operation modes.
BMP280 supports two ways of communication: spi and i2c.
This driver provides only i2c communication.
The driver works only with BMP280 and BME280 sensors. For BMP080/BMP180 there's
a separate driver. Even though BMP280 is a successor of BMP180 they are not
compatible. They have different registers and different operation modes.
BMP280 supports two ways of communication: spi and i2c. This driver provides
only i2c communication.
The driver is written for [esp-open-rtos](https://github.com/SuperHouse/esp-open-rtos)
framework and requires [i2c driver](https://github.com/SuperHouse/esp-open-rtos/tree/master/extras/i2c)
from it.
@ -18,17 +18,21 @@ from it.
## Usage
Connect BMP280 module to you ESP8266 module and specify SCL and SDA pins:
Connect BMP280 or BME280 module to you ESP8266 module and initialize the I2C SCL and SDA pins:
```
const uint8_t scl_pin = 5;
const uint8_t sda_pin = 4;
const uint8_t scl_pin = 0;
const uint8_t sda_pin = 2;
i2c_init(scl_pin, sda_pin);
```
Pull up SDO pin of BMP280 in order to have address 0x77.
Or pull down SDO pin and change `#define BMP280_ADDRESS 0x77` to
`#define BMP280_ADDRESS 0x76`. Otherwise your sensor will not work.
By default address 0x77 is used, so SDO pin should be high.
Pull up SDO pin of BMP280 in order to have address 0x77 `BMP280_I2C_ADDRESS_1`.
Or pull down SDO pin for address 0x76 `BMP280_I2C_ADDRESS_0`. Otherwise your
sensor will not work.
The BMP280 or BME280 are auto-detected at initialization based on the chip ID
and this ID is stored in the device descriptor.
BMP280 supports two operation modes.
@ -48,21 +52,26 @@ whose time is defined by standby_time.
### Forced mode
```
const uint8_t scl_pin = 5;
const uint8_t sda_pin = 4;
bmp280_params_t params;
float pressure, temperature;
float pressure, temperature, humidity;
bmp280_init_default_params(&params);
params.mode = BMP280_MODE_FORCED;
bmp280_init(&params, scl_pin, sda_pin);
bmp280_t bmp280_dev;
bmp280_dev.i2c_addr = BMP280_I2C_ADDRESS_0;
bmp280_init(&bmp280_dev, &params);
bool bme280p = bmp280_dev.id == BME280_CHIP_ID;
while(1) {
bmp280_force_measurement();
while (bmp280_is_measuring()) {}; // wait for measurement to complete
bmp280_force_measurement(&bmp280_dev));
// wait for measurement to complete
while (bmp280_is_measuring(&bmp280_dev)) {};
bmp280_read(&temperature, &pressure);
printf("Pressure: %.2f Pa, Temperature: %.2f C\n", pressure, temperature);
bmp280_read_float(&bmp280_dev, &temperature, &pressure, &humidity);
printf("Pressure: %.2f Pa, Temperature: %.2f C", pressure, temperature);
if (bme280p)
printf(", Humidity: %.2f\n", humidity);
vTaskDelay(1000 / portTICK_RATE_MS);
}
```
@ -71,14 +80,22 @@ while (1) {
```
bmp280_params_t params;
float pressure, temperature;
float pressure, temperature, humidity;
bmp280_init_default_params(&params);
bmp280_init(&params, scl_pin, sda_pin);
bmp280_t bmp280_dev;
bmp280_dev.i2c_addr = BMP280_I2C_ADDRESS_0;
bmp280_init(&bmp280_dev, &params);
bool bme280p = bmp280_dev.id == BME280_CHIP_ID;
while(1) {
bmp280_read(&temperature, &pressure);
printf("Pressure: %.2f Pa, Temperature: %.2f C\n", pressure, temperature);
bmp280_read_float(&bmp280_dev, &temperature, &pressure, &humidity);
printf("Pressure: %.2f Pa, Temperature: %.2f C", pressure, temperature);
if (bme280p)
printf(", Humidity: %.2f\n", humidity);
else
printf("\n");
vTaskDelay(1000 / portTICK_RATE_MS);
}
```

340
extras/bmp280/bmp280.c
View file

@ -21,10 +21,10 @@
* 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__);
@ -46,116 +46,150 @@
#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_CHIP_ID 0x58 /* BMP280 has chip-id 0x58 */
#define BMP280_RESET_VALUE 0xB6
typedef struct __attribute__((packed)) {
uint16_t dig_T1;
int16_t dig_T2;
int16_t dig_T3;
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;
} BMP280_Calib;
static BMP280_Calib calib_data;
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 uint8_t read_register8(uint8_t addr)
static bool read_register16(uint8_t i2c_addr, uint8_t addr, uint16_t *value)
{
uint8_t r = 0;
if (!i2c_slave_read(BMP280_ADDRESS, addr, &r, 1)) {
r = 0;
}
return r;
}
/**
* Even though value is signed the actual value is always positive.
* So, no need to take care of sign bit.
*/
static bool read_register24(uint8_t addr, int32_t *value)
{
uint8_t d[] = {0, 0, 0};
if (i2c_slave_read(BMP280_ADDRESS, addr, d, sizeof(d))) {
*value = d[0];
*value <<= 8;
*value |= d[1];
*value <<= 4;
*value |= d[2]>>4;
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 check_chip_id()
static bool read_calibration_data(bmp280_t *dev)
{
return (read_register8(BMP280_REG_ID)==BMP280_CHIP_ID);
}
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)) {
static bool read_calibration_data()
{
if (!i2c_slave_read(BMP280_ADDRESS, BMP280_REG_CALIB,
(uint8_t*)&calib_data, sizeof(calib_data))) {
return false;
}
debug("Calibration data received:");
debug("dig_T1=%d", calib_data.dig_T1);
debug("dig_T2=%d", calib_data.dig_T2);
debug("dig_T3=%d", calib_data.dig_T3);
debug("dig_P1=%d", calib_data.dig_P1);
debug("dig_P2=%d", calib_data.dig_P2);
debug("dig_P3=%d", calib_data.dig_P3);
debug("dig_P4=%d", calib_data.dig_P4);
debug("dig_P5=%d", calib_data.dig_P5);
debug("dig_P6=%d", calib_data.dig_P6);
debug("dig_P7=%d", calib_data.dig_P7);
debug("dig_P8=%d", calib_data.dig_P8);
debug("dig_P9=%d", calib_data.dig_P9);
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;
}
static bool write_register8(uint8_t addr, uint8_t value)
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(BMP280_ADDRESS, d, 2);
return i2c_slave_write(i2c_addr, d, 2);
}
bool bmp280_init(bmp280_params_t *params, uint8_t scl_pin, uint8_t sda_pin)
bool bmp280_init(bmp280_t *dev, bmp280_params_t *params)
{
i2c_init(scl_pin, sda_pin);
if (!check_chip_id()) {
debug("Sensor not found or wrong sensor version");
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 (!read_calibration_data()) {
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(BMP280_REG_CONFIG, config)) {
if (!write_register8(i2c_addr, BMP280_REG_CONFIG, config)) {
debug("Failed configuring sensor");
return false;
}
@ -170,30 +204,46 @@ bool bmp280_init(bmp280_params_t *params, uint8_t scl_pin, uint8_t sda_pin)
uint8_t ctrl = (oversampling_temp << 5) | (params->oversampling << 2)
| (params->mode);
debug("Writing ctrl reg=%x", ctrl);
if (!write_register8(BMP280_REG_CTRL, ctrl)) {
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()
bool bmp280_force_measurement(bmp280_t *dev)
{
uint8_t ctrl = read_register8(BMP280_REG_CTRL);
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(BMP280_REG_CTRL, ctrl)) {
if (!write_register8(dev->i2c_addr, BMP280_REG_CTRL, ctrl)) {
debug("Failed starting forced mode");
return false;
}
return true;
}
bool bmp280_is_measuring()
bool bmp280_is_measuring(bmp280_t *dev)
{
uint8_t status = read_register8(BMP280_REG_STATUS);
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;
@ -207,82 +257,130 @@ bool bmp280_is_measuring()
*
* Return value is in degrees Celsius.
*/
static inline float compensate_temperature(int32_t raw_temp, int32_t *fine_temp)
static inline int32_t compensate_temperature(bmp280_t *dev,
int32_t adc_temp, int32_t *fine_temp)
{
int32_t var1, var2, T;
int32_t var1, var2;
var1 = ((((raw_temp>>3) - ((int32_t)calib_data.dig_T1<<1)))
* ((int32_t)calib_data.dig_T2)) >> 11;
var2 = (((((raw_temp>>4) - ((int32_t)calib_data.dig_T1))
* ((raw_temp>>4) - ((int32_t)calib_data.dig_T1))) >> 12)
* ((int32_t)calib_data.dig_T3)) >> 14;
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;
T = (*fine_temp * 5 + 128) >> 8;
return (float)T/100;
return (*fine_temp * 5 + 128) >> 8;
}
/**
* Compensation algorithm is taken from BMP280 datasheet.
*
* Return value is in Pa.
* Return value is in Pa, 24 integer bits and 8 fractional bits.
*/
static inline float compensate_pressure(int32_t raw_press, int32_t fine_temp)
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)calib_data.dig_P6;
var2 = var2 + ((var1*(int64_t)calib_data.dig_P5)<<17);
var2 = var2 + (((int64_t)calib_data.dig_P4)<<35);
var1 = ((var1 * var1 * (int64_t)calib_data.dig_P3)>>8) +
((var1 * (int64_t)calib_data.dig_P2)<<12);
var1 = (((((int64_t)1)<<47)+var1))*((int64_t)calib_data.dig_P1)>>33;
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 - raw_press;
p = 1048576 - adc_press;
p = (((p << 31) - var2) * 3125) / var1;
var1 = (((int64_t)calib_data.dig_P9) * (p>>13) * (p>>13)) >> 25;
var2 = (((int64_t)calib_data.dig_P8) * p) >> 19;
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)calib_data.dig_P7)<<4);
return (float)p/256;
p = ((p + var1 + var2) >> 8) + ((int64_t)dev->dig_P7 << 4);
return p;
}
bool bmp280_read(float *temperature, float *pressure)
/**
* 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 raw_pressure;
int32_t raw_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 (!read_register24(BMP280_REG_TEMP, &raw_temp)) {
debug("Failed reading temperature");
return false;
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);
}
if (!read_register24(BMP280_REG_PRESSURE, &raw_pressure)) {
debug("Failed reading pressure");
return false;
}
debug("Raw temperature: %d", raw_temp);
debug("Raw pressure: %d", raw_pressure);
*temperature = compensate_temperature(raw_temp, &fine_temp);
*pressure = compensate_pressure(raw_pressure, fine_temp);
return true;
}
bool bmp280_soft_reset()
bool bmp280_read_float(bmp280_t *dev, float *temperature,
float *pressure, float *humidity)
{
if (!write_register8(BMP280_REG_RESET, BMP280_RESET_VALUE)) {
debug("Failed resetting sensor");
return false;
}
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;
}

82
extras/bmp280/bmp280.h
View file

@ -33,10 +33,14 @@
// #define BMP280_DEBUG
/**
* BMP280 address is 0x77 if SDO pin is high,
* Address is 0x76 if SDO pin is low.
* BMP280 or BME280 address is 0x77 if SDO pin is high, and is 0x76 if
* SDO pin is low.
*/
#define BMP280_ADDRESS 0x77
#define BMP280_I2C_ADDRESS_0 0x76
#define BMP280_I2C_ADDRESS_1 0x77
#define BMP280_CHIP_ID 0x58 /* BMP280 has chip-id 0x58 */
#define BME280_CHIP_ID 0x60 /* BME280 has chip-id 0x60 */
/**
* Mode of BMP280 module operation.
@ -78,8 +82,8 @@ typedef enum {
BMP280_STANDBY_250 = 3, /* stand by time 250ms */
BMP280_STANDBY_500 = 4, /* stand by time 500ms */
BMP280_STANDBY_1000 = 5, /* stand by time 1s */
BMP280_STANDBY_2000 = 6, /* stand by time 2s */
BMP280_STANDBY_4000 = 7, /* stand by time 4s */
BMP280_STANDBY_2000 = 6, /* stand by time 2s BMP280, 10ms BME280 */
BMP280_STANDBY_4000 = 7, /* stand by time 4s BMP280, 20ms BME280 */
} BMP280_StandbyTime;
/**
@ -90,10 +94,37 @@ typedef struct {
BMP280_Mode mode;
BMP280_Filter filter;
BMP280_Oversampling oversampling; // pressure oversampling
BMP280_Oversampling oversampling_humidity;
BMP280_StandbyTime standby;
} bmp280_params_t;
typedef struct {
uint16_t dig_T1;
int16_t dig_T2;
int16_t dig_T3;
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;
/* Humidity compensation for BME280 */
uint8_t dig_H1;
int16_t dig_H2;
uint8_t dig_H3;
int16_t dig_H4;
int16_t dig_H5;
int8_t dig_H6;
uint8_t i2c_addr; /* I2C address. */
uint8_t id; /* Chip ID */
} bmp280_t;
/**
* Initialize default parameters.
* Default configuration:
@ -105,33 +136,52 @@ typedef struct {
void bmp280_init_default_params(bmp280_params_t *params);
/**
* Initialize BMP280 module.
* Initialize BMP280 module, probes for the device, soft resets the device,
* reads the calibration constants, and configures the device using the supplied
* parameters. Returns true on success otherwise false.
*
* The I2C address is assumed to have been initialized in the dev, and
* may be either BMP280_I2C_ADDRESS_0 or BMP280_I2C_ADDRESS_1. If the I2C
* address is unknown then try initializing each in turn.
*
* This may be called again to soft reset the device and initialize it again.
*/
bool bmp280_init(bmp280_params_t *params, uint8_t scl_pin, uint8_t sda_pin);
bool bmp280_init(bmp280_t *dev, bmp280_params_t *params);
/**
* Start measurement in forced mode.
* The module remains in forced mode after this call.
* Do not call this method in normal mode.
*/
bool bmp280_force_measurement();
bool bmp280_force_measurement(bmp280_t *dev);
/**
* Check if BMP280 is busy with measuring temperature/pressure.
* Return true if BMP280 is busy.
*/
bool bmp280_is_measuring();
bool bmp280_is_measuring(bmp280_t *dev);
/**
* Read compensated temperature and pressure data.
* Read compensated temperature and pressure data:
*
* Temperature in degrees Celsius times 100.
*
* Pressure in Pascals in fixed point 24 bit integer 8 bit fraction format.
*
* Humidity is optional and only read for the BME280, in percent relative
* humidity as a fixed point 22 bit interger and 10 bit fraction format.
*/
bool bmp280_read_fixed(bmp280_t *dev, int32_t *temperature,
uint32_t *pressure, uint32_t *humidity);
/**
* Read compensated temperature and pressure data:
* Temperature in degrees Celsius.
* Pressure in Pascals.
* Humidity is optional and only read for the BME280, in percent relative
* humidity.
*/
bool bmp280_read(float *temperature, float *pressure);
/**
* Restart BMP280 module.
*/
bool bmp280_soft_reset();
bool bmp280_read_float(bmp280_t *dev, float *temperature,
float *pressure, float *humidity);
#endif // __BMP280_H__