3 This package contains the Bosch Sensortec's BME280 pressure sensor driver (sensor API)
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5 The sensor driver package includes bme280.c, bme280.h and bme280_defs.h files.
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8 File | Version | Date
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9 --------------|---------|------------
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10 bme280.c | 3.4.1 | 10 Jan 2020
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11 bme280.h | 3.4.1 | 10 Jan 2020
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12 bme280_defs.h | 3.4.1 | 10 Jan 2020
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14 ## Integration details
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15 * Integrate bme280.h, bme280_defs.h and bme280.c file in to the project.
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16 * Include the bme280.h file in your code like below.
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22 * bme280_defs.h : This header file has the constants, macros and datatype declarations.
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23 * bme280.h : This header file contains the declarations of the sensor driver APIs.
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24 * bme280.c : This source file contains the definitions of the sensor driver APIs.
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26 ## Supported sensor interfaces
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30 SPI 3-wire is currently not supported in the API.
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32 ### Initializing the sensor
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33 To initialize the sensor, user need to create a device structure. User can do this by
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34 creating an instance of the structure bme280_dev. After creating the device strcuture, user
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35 need to fill in the various parameters as shown below.
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37 #### Example for SPI 4-Wire
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39 struct bme280_dev dev;
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40 int8_t rslt = BME280_OK;
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42 /* Sensor_0 interface over SPI with native chip select line */
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44 dev.intf = BME280_SPI_INTF;
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45 dev.read = user_spi_read;
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46 dev.write = user_spi_write;
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47 dev.delay_ms = user_delay_ms;
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49 rslt = bme280_init(&dev);
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51 #### Example for I2C
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53 struct bme280_dev dev;
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54 int8_t rslt = BME280_OK;
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56 dev.dev_id = BME280_I2C_ADDR_PRIM;
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57 dev.intf = BME280_I2C_INTF;
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58 dev.read = user_i2c_read;
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59 dev.write = user_i2c_write;
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60 dev.delay_ms = user_delay_ms;
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62 rslt = bme280_init(&dev);
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64 Regarding compensation functions for temperature,pressure and humidity we have two implementations.
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65 1) Double precision floating point version
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68 By default, integer version is used in the API. If the user needs the floating point version, the user has to uncomment BME280_FLOAT_ENABLE macro in bme280_defs.h file or add that to the compiler flags.
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70 In integer compensation functions, we also have below two implementations for pressure.
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71 1) For 32 bit machine.
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72 2) For 64 bit machine.
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74 By default, 64 bit variant is used in the API. If the user wants 32 bit variant, the user can disable the
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75 macro BME280_64BIT_ENABLE in bme280_defs.h file.
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77 ### Sensor data units
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78 > The sensor data units depends on the following macros being enabled or not,
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79 > (in bme280_defs.h file or as compiler macros)
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80 > * BME280_FLOAT_ENABLE
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81 > * BME280_64BIT_ENABLE
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83 In case of the macro "BME280_FLOAT_ENABLE" enabled,
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84 The outputs are in double and the units are
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86 - °C for temperature
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87 - % relative humidity
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88 - Pascal for pressure
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90 In case if "BME280_FLOAT_ENABLE" is not enabled, then it is
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92 - int32_t for temperature with the units 100 * °C
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93 - uint32_t for humidity with the units 1024 * % relative humidity
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94 - uint32_t for pressure
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95 If macro "BME280_64BIT_ENABLE" is enabled, which it is by default, the unit is 100 * Pascal
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96 If this macro is disabled, Then the unit is in Pascal
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98 ### Stream sensor data
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99 #### Stream sensor data in forced mode
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102 int8_t stream_sensor_data_forced_mode(struct bme280_dev *dev)
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105 uint8_t settings_sel;
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106 uint32_t req_delay;
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107 struct bme280_data comp_data;
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109 /* Recommended mode of operation: Indoor navigation */
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110 dev->settings.osr_h = BME280_OVERSAMPLING_1X;
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111 dev->settings.osr_p = BME280_OVERSAMPLING_16X;
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112 dev->settings.osr_t = BME280_OVERSAMPLING_2X;
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113 dev->settings.filter = BME280_FILTER_COEFF_16;
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115 settings_sel = BME280_OSR_PRESS_SEL | BME280_OSR_TEMP_SEL | BME280_OSR_HUM_SEL | BME280_FILTER_SEL;
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117 rslt = bme280_set_sensor_settings(settings_sel, dev);
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119 /*Calculate the minimum delay required between consecutive measurement based upon the sensor enabled
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120 * and the oversampling configuration. */
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121 req_delay = bme280_cal_meas_delay(&dev->settings);
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123 printf("Temperature, Pressure, Humidity\r\n");
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124 /* Continuously stream sensor data */
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126 rslt = bme280_set_sensor_mode(BME280_FORCED_MODE, dev);
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127 /* Wait for the measurement to complete and print data @25Hz */
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128 dev->delay_ms(req_delay);
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129 rslt = bme280_get_sensor_data(BME280_ALL, &comp_data, dev);
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130 print_sensor_data(&comp_data);
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135 void print_sensor_data(struct bme280_data *comp_data)
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137 #ifdef BME280_FLOAT_ENABLE
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138 printf("%0.2f, %0.2f, %0.2f\r\n",comp_data->temperature, comp_data->pressure, comp_data->humidity);
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140 printf("%ld, %ld, %ld\r\n",comp_data->temperature, comp_data->pressure, comp_data->humidity);
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144 ##### Stream sensor data in normal mode
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146 int8_t stream_sensor_data_normal_mode(struct bme280_dev *dev)
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149 uint8_t settings_sel;
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150 struct bme280_data comp_data;
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152 /* Recommended mode of operation: Indoor navigation */
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153 dev->settings.osr_h = BME280_OVERSAMPLING_1X;
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154 dev->settings.osr_p = BME280_OVERSAMPLING_16X;
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155 dev->settings.osr_t = BME280_OVERSAMPLING_2X;
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156 dev->settings.filter = BME280_FILTER_COEFF_16;
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157 dev->settings.standby_time = BME280_STANDBY_TIME_62_5_MS;
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159 settings_sel = BME280_OSR_PRESS_SEL;
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160 settings_sel |= BME280_OSR_TEMP_SEL;
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161 settings_sel |= BME280_OSR_HUM_SEL;
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162 settings_sel |= BME280_STANDBY_SEL;
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163 settings_sel |= BME280_FILTER_SEL;
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164 rslt = bme280_set_sensor_settings(settings_sel, dev);
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165 rslt = bme280_set_sensor_mode(BME280_NORMAL_MODE, dev);
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167 printf("Temperature, Pressure, Humidity\r\n");
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169 /* Delay while the sensor completes a measurement */
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171 rslt = bme280_get_sensor_data(BME280_ALL, &comp_data, dev);
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172 print_sensor_data(&comp_data);
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178 void print_sensor_data(struct bme280_data *comp_data)
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180 #ifdef BME280_FLOAT_ENABLE
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181 printf("%0.2f, %0.2f, %0.2f\r\n",comp_data->temperature, comp_data->pressure, comp_data->humidity);
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183 printf("%ld, %ld, %ld\r\n",comp_data->temperature, comp_data->pressure, comp_data->humidity);
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188 ### Templates for function pointers
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191 void user_delay_ms(uint32_t period)
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194 * Return control or wait,
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195 * for a period amount of milliseconds
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199 int8_t user_spi_read(uint8_t dev_id, uint8_t reg_addr, uint8_t *reg_data, uint16_t len)
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201 int8_t rslt = 0; /* Return 0 for Success, non-zero for failure */
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204 * The parameter dev_id can be used as a variable to select which Chip Select pin has
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205 * to be set low to activate the relevant device on the SPI bus
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209 * Data on the bus should be like
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210 * |----------------+---------------------+-------------|
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211 * | MOSI | MISO | Chip Select |
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212 * |----------------+---------------------|-------------|
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213 * | (don't care) | (don't care) | HIGH |
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214 * | (reg_addr) | (don't care) | LOW |
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215 * | (don't care) | (reg_data[0]) | LOW |
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216 * | (....) | (....) | LOW |
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217 * | (don't care) | (reg_data[len - 1]) | LOW |
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218 * | (don't care) | (don't care) | HIGH |
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219 * |----------------+---------------------|-------------|
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225 int8_t user_spi_write(uint8_t dev_id, uint8_t reg_addr, uint8_t *reg_data, uint16_t len)
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227 int8_t rslt = 0; /* Return 0 for Success, non-zero for failure */
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230 * The parameter dev_id can be used as a variable to select which Chip Select pin has
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231 * to be set low to activate the relevant device on the SPI bus
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235 * Data on the bus should be like
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236 * |---------------------+--------------+-------------|
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237 * | MOSI | MISO | Chip Select |
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238 * |---------------------+--------------|-------------|
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239 * | (don't care) | (don't care) | HIGH |
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240 * | (reg_addr) | (don't care) | LOW |
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241 * | (reg_data[0]) | (don't care) | LOW |
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242 * | (....) | (....) | LOW |
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243 * | (reg_data[len - 1]) | (don't care) | LOW |
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244 * | (don't care) | (don't care) | HIGH |
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245 * |---------------------+--------------|-------------|
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251 int8_t user_i2c_read(uint8_t dev_id, uint8_t reg_addr, uint8_t *reg_data, uint16_t len)
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253 int8_t rslt = 0; /* Return 0 for Success, non-zero for failure */
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256 * The parameter dev_id can be used as a variable to store the I2C address of the device
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260 * Data on the bus should be like
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261 * |------------+---------------------|
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262 * | I2C action | Data |
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263 * |------------+---------------------|
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265 * | Write | (reg_addr) |
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268 * | Read | (reg_data[0]) |
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269 * | Read | (....) |
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270 * | Read | (reg_data[len - 1]) |
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272 * |------------+---------------------|
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278 int8_t user_i2c_write(uint8_t dev_id, uint8_t reg_addr, uint8_t *reg_data, uint16_t len)
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280 int8_t rslt = 0; /* Return 0 for Success, non-zero for failure */
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283 * The parameter dev_id can be used as a variable to store the I2C address of the device
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287 * Data on the bus should be like
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288 * |------------+---------------------|
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289 * | I2C action | Data |
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290 * |------------+---------------------|
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292 * | Write | (reg_addr) |
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293 * | Write | (reg_data[0]) |
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294 * | Write | (....) |
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295 * | Write | (reg_data[len - 1]) |
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297 * |------------+---------------------|
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305 ## Copyright (C) 2016 - 2017 Bosch Sensortec GmbH