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Environmental Sensor FeatherWing Sample

Introduction​

The sensor sample sets up the sensors available on the Environmental Sensor FeatherWing v1 and reads values from the sensors in a loop.

Project Configuration​

In order to use the sensors on the FeatherWing, the following directives are enabled in the prj.conf file:

CONFIG_I2C=y
CONFIG_I2C_NRFX=y
CONFIG_I2C_2=y
CONFIG_I2C_2_NRF_TWIM=y

CONFIG_SENSOR=y

These include and enable the I2C driver and the sensor library.

Additionally, the sample configures the following directives in the prj.conf:

CONFIG_SENSOR=y

CONFIG_BME280=y

CONFIG_CCS811=y
CONFIG_CCS811_GPIO_WAKEUP=y
CONFIG_CCS811_GPIO_DEV_NAME="GPIO_0"
CONFIG_CCS811_GPIO_WAKEUP_PIN_NUM=30

CONFIG_SI7060=y

CONFIG_OPT3001=y

These enable the Zephyr sensor driver and the use of the individual sensor drivers.

Code Explanation​

The sample initializes each of the sensors by getting the device bindings from the Icarus device tree (they are added to the device tree by the overlay file):

struct device* bme280 = device_get_binding("BME280");
struct device* ccs881 = device_get_binding("CCS811");
struct device* opt3001 = device_get_binding("OPT3001");
struct device* si7060 = device_get_binding("SI7060");

Then it reads each sensor's values in a loop using the Zephyr sensor library and prints them.

Reading Sensor Values​

The following code shows how the measured values are retrieved from the sensors:

BME280​

sensor_sample_fetch(bme280);

struct sensor_value temp;
sensor_channel_get(bme280, SENSOR_CHAN_AMBIENT_TEMP, &temp);

struct sensor_value press;
sensor_channel_get(bme280, SENSOR_CHAN_PRESS, &press);

struct sensor_value humidity;
sensor_channel_get(bme280, SENSOR_CHAN_HUMIDITY, &humidity);

CCS811​

sensor_sample_fetch(ccs881);

struct sensor_value co2;
sensor_channel_get(ccs881, SENSOR_CHAN_CO2, &co2);

struct sensor_value voc;
sensor_channel_get(ccs881, SENSOR_CHAN_VOC, &voc);

OPT3001​

sensor_sample_fetch(opt3001);

struct sensor_value lux;
sensor_channel_get(opt3001, SENSOR_CHAN_LIGHT, &lux);

SI7060​

sensor_sample_fetch(si7060);

struct sensor_value temp;
sensor_channel_get(si7060, SENSOR_CHAN_AMBIENT_TEMP, &temp);

Converting Sensor Values​

In order to convert the value returned from the sensors to a double, the sensor library provides a helper method:

double value_float = sensor_value_to_double(&sensor_value);
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