f0c43ff5d5
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.
386 lines
12 KiB
C
386 lines
12 KiB
C
/**
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* The MIT License (MIT)
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*
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* Copyright (c) 2016 sheinz (https://github.com/sheinz)
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*
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* Permission is hereby granted, free of charge, to any person obtaining a copy
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* of this software and associated documentation files (the "Software"), to deal
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* in the Software without restriction, including without limitation the rights
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* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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* copies of the Software, and to permit persons to whom the Software is
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* furnished to do so, subject to the following conditions:
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*
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* The above copyright notice and this permission notice shall be included in
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* all copies or substantial portions of the Software.
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*
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* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
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* AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
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* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
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* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
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* THE SOFTWARE.
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*/
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#include <stddef.h>
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#include "bmp280.h"
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#include "i2c/i2c.h"
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#ifdef BMP280_DEBUG
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#include <stdio.h>
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#define debug(fmt, ...) printf("%s" fmt "\n", "bmp280: ", ## __VA_ARGS__);
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#else
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#define debug(fmt, ...)
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#endif
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/**
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* BMP280 registers
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*/
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#define BMP280_REG_TEMP_XLSB 0xFC /* bits: 7-4 */
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#define BMP280_REG_TEMP_LSB 0xFB
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#define BMP280_REG_TEMP_MSB 0xFA
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#define BMP280_REG_TEMP (BMP280_REG_TEMP_MSB)
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#define BMP280_REG_PRESS_XLSB 0xF9 /* bits: 7-4 */
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#define BMP280_REG_PRESS_LSB 0xF8
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#define BMP280_REG_PRESS_MSB 0xF7
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#define BMP280_REG_PRESSURE (BMP280_REG_PRESS_MSB)
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#define BMP280_REG_CONFIG 0xF5 /* bits: 7-5 t_sb; 4-2 filter; 0 spi3w_en */
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#define BMP280_REG_CTRL 0xF4 /* bits: 7-5 osrs_t; 4-2 osrs_p; 1-0 mode */
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#define BMP280_REG_STATUS 0xF3 /* bits: 3 measuring; 0 im_update */
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#define BMP280_REG_CTRL_HUM 0xF2 /* bits: 2-0 osrs_h; */
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#define BMP280_REG_RESET 0xE0
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#define BMP280_REG_ID 0xD0
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#define BMP280_REG_CALIB 0x88
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#define BMP280_REG_HUM_CALIB 0x88
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#define BMP280_RESET_VALUE 0xB6
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void bmp280_init_default_params(bmp280_params_t *params)
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{
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params->mode = BMP280_MODE_NORMAL;
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params->filter = BMP280_FILTER_OFF;
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params->oversampling = BMP280_STANDARD;
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params->oversampling_humidity = BMP280_STANDARD;
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params->standby = BMP280_STANDBY_250;
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}
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static bool read_register16(uint8_t i2c_addr, uint8_t addr, uint16_t *value)
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{
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uint8_t d[] = {0, 0};
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if (i2c_slave_read(i2c_addr, addr, d, sizeof(d))) {
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*value = d[0] | (d[1] << 8);
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return true;
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}
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return false;
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}
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static bool read_calibration_data(bmp280_t *dev)
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{
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uint8_t i2c_addr = dev->i2c_addr;
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if (read_register16(i2c_addr, 0x88, &dev->dig_T1) &&
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read_register16(i2c_addr, 0x8a, (uint16_t *)&dev->dig_T2) &&
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read_register16(i2c_addr, 0x8c, (uint16_t *)&dev->dig_T3) &&
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read_register16(i2c_addr, 0x8e, &dev->dig_P1) &&
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read_register16(i2c_addr, 0x90, (uint16_t *)&dev->dig_P2) &&
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read_register16(i2c_addr, 0x92, (uint16_t *)&dev->dig_P3) &&
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read_register16(i2c_addr, 0x94, (uint16_t *)&dev->dig_P4) &&
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read_register16(i2c_addr, 0x96, (uint16_t *)&dev->dig_P5) &&
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read_register16(i2c_addr, 0x98, (uint16_t *)&dev->dig_P6) &&
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read_register16(i2c_addr, 0x9a, (uint16_t *)&dev->dig_P7) &&
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read_register16(i2c_addr, 0x9c, (uint16_t *)&dev->dig_P8) &&
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read_register16(i2c_addr, 0x9e, (uint16_t *)&dev->dig_P9)) {
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debug("Calibration data received:");
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debug("dig_T1=%d", dev->dig_T1);
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debug("dig_T2=%d", dev->dig_T2);
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debug("dig_T3=%d", dev->dig_T3);
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debug("dig_P1=%d", dev->dig_P1);
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debug("dig_P2=%d", dev->dig_P2);
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debug("dig_P3=%d", dev->dig_P3);
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debug("dig_P4=%d", dev->dig_P4);
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debug("dig_P5=%d", dev->dig_P5);
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debug("dig_P6=%d", dev->dig_P6);
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debug("dig_P7=%d", dev->dig_P7);
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debug("dig_P8=%d", dev->dig_P8);
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debug("dig_P9=%d", dev->dig_P9);
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return true;
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}
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return false;
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}
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static bool read_hum_calibration_data(bmp280_t *dev)
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{
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uint8_t i2c_addr = dev->i2c_addr;
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uint16_t h4, h5;
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if (i2c_slave_read(i2c_addr, 0xa1, &dev->dig_H1, 1) &&
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read_register16(i2c_addr, 0xe1, (uint16_t *)&dev->dig_H2) &&
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i2c_slave_read(i2c_addr, 0xe3, &dev->dig_H3, 1) &&
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read_register16(i2c_addr, 0xe4, &h4) &&
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read_register16(i2c_addr, 0xe5, &h5) &&
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i2c_slave_read(i2c_addr, 0xe7, (uint8_t *)&dev->dig_H6, 1)) {
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dev->dig_H4 = (h4 & 0x00ff) << 4 | (h4 & 0x0f00) >> 8;
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dev->dig_H5 = h5 >> 4;
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debug("Calibration data received:");
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debug("dig_H1=%d", dev->dig_H1);
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debug("dig_H2=%d", dev->dig_H2);
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debug("dig_H3=%d", dev->dig_H3);
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debug("dig_H4=%d", dev->dig_H4);
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debug("dig_H5=%d", dev->dig_H5);
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debug("dig_H6=%d", dev->dig_H6);
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return true;
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}
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return false;
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}
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static bool write_register8(uint8_t i2c_addr, uint8_t addr, uint8_t value)
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{
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uint8_t d[] = {addr, value};
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return i2c_slave_write(i2c_addr, d, 2);
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}
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bool bmp280_init(bmp280_t *dev, bmp280_params_t *params)
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{
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uint8_t i2c_addr = dev->i2c_addr;
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if (i2c_addr != BMP280_I2C_ADDRESS_0 && i2c_addr != BMP280_I2C_ADDRESS_1) {
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debug("Invalid I2C address");
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return false;
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}
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if (!i2c_slave_read(i2c_addr, BMP280_REG_ID, &dev->id, 1)) {
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debug("Sensor not found");
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return false;
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}
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if (dev->id != BMP280_CHIP_ID && dev->id != BME280_CHIP_ID) {
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debug("Sensor wrong version");
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return false;
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}
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// Soft reset.
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if (!write_register8(i2c_addr, BMP280_REG_RESET, BMP280_RESET_VALUE)) {
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debug("Failed resetting sensor");
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return false;
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}
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// Wait until finished copying over the NVP data.
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while (1) {
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uint8_t status;
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if (i2c_slave_read(i2c_addr, BMP280_REG_STATUS, &status, 1) && (status & 1) == 0)
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break;
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}
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if (!read_calibration_data(dev)) {
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debug("Failed to read calibration data");
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return false;
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}
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if (dev->id == BME280_CHIP_ID && !read_hum_calibration_data(dev)) {
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debug("Failed to read humidity calibration data");
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return false;
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}
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uint8_t config = (params->standby << 5) | (params->filter << 2);
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debug("Writing config reg=%x", config);
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if (!write_register8(i2c_addr, BMP280_REG_CONFIG, config)) {
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debug("Failed configuring sensor");
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return false;
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}
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uint8_t oversampling_temp =
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(params->oversampling == BMP280_ULTRA_HIGH_RES) ? 2 : 1;
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if (params->mode == BMP280_MODE_FORCED) {
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params->mode = BMP280_MODE_SLEEP; // initial mode for forced is sleep
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}
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uint8_t ctrl = (oversampling_temp << 5) | (params->oversampling << 2)
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| (params->mode);
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if (dev->id == BME280_CHIP_ID) {
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// Write crtl hum reg first, only active after write to BMP280_REG_CTRL.
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uint8_t ctrl_hum = params->oversampling_humidity;
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debug("Writing ctrl hum reg=%x", ctrl_hum);
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if (!write_register8(i2c_addr, BMP280_REG_CTRL_HUM, ctrl_hum)) {
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debug("Failed controlling sensor");
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return false;
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}
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}
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debug("Writing ctrl reg=%x", ctrl);
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if (!write_register8(i2c_addr, BMP280_REG_CTRL, ctrl)) {
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debug("Failed controlling sensor");
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return false;
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}
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return true;
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}
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bool bmp280_force_measurement(bmp280_t *dev)
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{
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uint8_t ctrl;
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if (!i2c_slave_read(dev->i2c_addr, BMP280_REG_CTRL, &ctrl, 1))
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return false;
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ctrl &= ~0b11; // clear two lower bits
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ctrl |= BMP280_MODE_FORCED;
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debug("Writing ctrl reg=%x", ctrl);
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if (!write_register8(dev->i2c_addr, BMP280_REG_CTRL, ctrl)) {
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debug("Failed starting forced mode");
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return false;
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}
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return true;
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}
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bool bmp280_is_measuring(bmp280_t *dev)
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{
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uint8_t status;
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if (!i2c_slave_read(dev->i2c_addr, BMP280_REG_STATUS, &status, 1))
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return false;
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if (status & (1 << 3)) {
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debug("Status: measuring");
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return true;
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}
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debug("Status: idle");
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return false;
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}
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/**
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* Compensation algorithm is taken from BMP280 datasheet.
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*
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* Return value is in degrees Celsius.
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*/
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static inline int32_t compensate_temperature(bmp280_t *dev,
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int32_t adc_temp, int32_t *fine_temp)
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{
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int32_t var1, var2;
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var1 = ((((adc_temp >> 3) - ((int32_t)dev->dig_T1 << 1)))
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* (int32_t)dev->dig_T2) >> 11;
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var2 = (((((adc_temp >> 4) - (int32_t)dev->dig_T1)
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* ((adc_temp >> 4) - (int32_t)dev->dig_T1)) >> 12)
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* (int32_t)dev->dig_T3) >> 14;
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*fine_temp = var1 + var2;
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return (*fine_temp * 5 + 128) >> 8;
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}
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/**
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* Compensation algorithm is taken from BMP280 datasheet.
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*
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* Return value is in Pa, 24 integer bits and 8 fractional bits.
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*/
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static inline uint32_t compensate_pressure(bmp280_t *dev,
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int32_t adc_press, int32_t fine_temp)
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{
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int64_t var1, var2, p;
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var1 = (int64_t)fine_temp - 128000;
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var2 = var1 * var1 * (int64_t)dev->dig_P6;
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var2 = var2 + ((var1 * (int64_t)dev->dig_P5) << 17);
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var2 = var2 + (((int64_t)dev->dig_P4) << 35);
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var1 = ((var1 * var1 * (int64_t)dev->dig_P3) >> 8) +
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((var1 * (int64_t)dev->dig_P2) << 12);
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var1 = (((int64_t)1 << 47) + var1) * ((int64_t)dev->dig_P1) >> 33;
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if (var1 == 0) {
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return 0; // avoid exception caused by division by zero
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}
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p = 1048576 - adc_press;
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p = (((p << 31) - var2) * 3125) / var1;
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var1 = ((int64_t)dev->dig_P9 * (p >> 13) * (p >> 13)) >> 25;
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var2 = ((int64_t)dev->dig_P8 * p) >> 19;
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p = ((p + var1 + var2) >> 8) + ((int64_t)dev->dig_P7 << 4);
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return p;
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}
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/**
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* Compensation algorithm is taken from BME280 datasheet.
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*
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* Return value is in Pa, 24 integer bits and 8 fractional bits.
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*/
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static inline uint32_t compensate_humidity(bmp280_t *dev,
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int32_t adc_hum, int32_t fine_temp)
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{
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int32_t v_x1_u32r;
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v_x1_u32r = fine_temp - (int32_t)76800;
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v_x1_u32r = ((((adc_hum << 14) - ((int32_t)dev->dig_H4 << 20) -
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((int32_t)dev->dig_H5 * v_x1_u32r)) +
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(int32_t)16384) >> 15) *
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(((((((v_x1_u32r * (int32_t)dev->dig_H6) >> 10) *
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(((v_x1_u32r * (int32_t)dev->dig_H3) >> 11) +
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(int32_t)32768)) >> 10) + (int32_t)2097152) *
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(int32_t)dev->dig_H2 + 8192) >> 14);
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v_x1_u32r = v_x1_u32r - (((((v_x1_u32r >> 15) * (v_x1_u32r >> 15)) >> 7) *
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(int32_t)dev->dig_H1) >> 4);
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v_x1_u32r = v_x1_u32r < 0 ? 0 : v_x1_u32r;
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v_x1_u32r = v_x1_u32r > 419430400 ? 419430400 : v_x1_u32r;
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return v_x1_u32r >> 12;
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}
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bool bmp280_read_fixed(bmp280_t *dev, int32_t *temperature,
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uint32_t *pressure, uint32_t *humidity)
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{
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int32_t adc_pressure;
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int32_t adc_temp;
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uint8_t data[8];
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// Only the BME280 supports reading the humidity.
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if (dev->id != BME280_CHIP_ID) {
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if (humidity)
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*humidity = 0;
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humidity = NULL;
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}
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// Need to read in one sequence to ensure they match.
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size_t size = humidity ? 8 : 6;
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if (!i2c_slave_read(dev->i2c_addr, 0xf7, data, size)) {
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debug("Failed reading");
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return false;
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}
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adc_pressure = data[0] << 12 | data[1] << 4 | data[2] >> 4;
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adc_temp = data[3] << 12 | data[4] << 4 | data[5] >> 4;
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debug("ADC temperature: %d", adc_temp);
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debug("ADC pressure: %d", adc_pressure);
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int32_t fine_temp;
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*temperature = compensate_temperature(dev, adc_temp, &fine_temp);
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*pressure = compensate_pressure(dev, adc_pressure, fine_temp);
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if (humidity) {
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int32_t adc_humidity = data[6] << 8 | data[7];
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debug("ADC humidity: %d", adc_humidity);
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*humidity = compensate_humidity(dev, adc_humidity, fine_temp);
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}
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return true;
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}
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bool bmp280_read_float(bmp280_t *dev, float *temperature,
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float *pressure, float *humidity)
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{
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int32_t fixed_temperature;
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uint32_t fixed_pressure;
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uint32_t fixed_humidity;
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if (bmp280_read_fixed(dev, &fixed_temperature, &fixed_pressure,
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humidity ? &fixed_humidity : NULL)) {
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*temperature = (float)fixed_temperature/100;
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*pressure = (float)fixed_pressure/256;
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if (humidity)
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*humidity = (float)fixed_humidity/1024;
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return true;
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}
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return false;
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}
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