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bme280 app: use forced mode, only measure when needed

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This commit is contained in:
Joey Castillo 2021-08-05 12:29:09 -04:00
parent 67e9d173ca
commit fb249f9b48
1 changed files with 13 additions and 2 deletions
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15
Sensor Watch BME280 Project/app.c
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@ -77,7 +77,7 @@ void app_setup() {
watch_i2c_write8(BME280_ADDRESS, BME280_REGISTER_CONTROL_HUMID, BME280_CONTROL_HUMID_SAMPLING_X16); watch_i2c_write8(BME280_ADDRESS, BME280_REGISTER_CONTROL_HUMID, BME280_CONTROL_HUMID_SAMPLING_X16);
watch_i2c_write8(BME280_ADDRESS, BME280_REGISTER_CONTROL, BME280_CONTROL_TEMPERATURE_SAMPLING_X16 | watch_i2c_write8(BME280_ADDRESS, BME280_REGISTER_CONTROL, BME280_CONTROL_TEMPERATURE_SAMPLING_X16 |
BME280_CONTROL_PRESSURE_SAMPLING_NONE | BME280_CONTROL_PRESSURE_SAMPLING_NONE |
BME280_CONTROL_MODE_NORMAL); BME280_CONTROL_MODE_FORCED);
watch_enable_display(); watch_enable_display();
@ -107,12 +107,22 @@ bool app_loop() {
switch (application_state.mode) { switch (application_state.mode) {
case MODE_TEMPERATURE: case MODE_TEMPERATURE:
// take one reading
watch_i2c_write8(BME280_ADDRESS, BME280_REGISTER_CONTROL, BME280_CONTROL_TEMPERATURE_SAMPLING_X16 |
BME280_CONTROL_MODE_FORCED);
// wait for reading to finish
while(watch_i2c_read8(BME280_ADDRESS, BME280_REGISTER_STATUS) & BME280_STATUS_UPDATING_MASK);
temperature = read_temperature(NULL); temperature = read_temperature(NULL);
sprintf(buf, "TE %4.1f#C", temperature); sprintf(buf, "TE %4.1f#C", temperature);
watch_display_string(buf, 0); watch_display_string(buf, 0);
watch_clear_pixel(1, 16); watch_clear_pixel(1, 16);
break; break;
case MODE_HUMIDITY: case MODE_HUMIDITY:
// take one reading
watch_i2c_write8(BME280_ADDRESS, BME280_REGISTER_CONTROL, BME280_CONTROL_TEMPERATURE_SAMPLING_X16 |
BME280_CONTROL_MODE_FORCED);
// wait for reading to finish
while(watch_i2c_read8(BME280_ADDRESS, BME280_REGISTER_STATUS) & BME280_STATUS_UPDATING_MASK);
temperature = read_temperature(&t_fine); temperature = read_temperature(&t_fine);
humidity = read_humidity(t_fine); humidity = read_humidity(t_fine);
sprintf(buf, "HU rH %3d", (int)humidity); sprintf(buf, "HU rH %3d", (int)humidity);
@ -155,7 +165,8 @@ float read_temperature(int32_t *p_t_fine) {
/** /**
* Reads the humidity from the BME280 * Reads the humidity from the BME280
* @param t_fine - the t_fine measurement from a call to read_temperature * @param t_fine - the t_fine measurement from a call to read_temperature
* @return a float indicating the temperature in degrees celsius. * @return a float indicating the relative humidity as a percentage from 0-100.
* @todo the returned value is glitchy, need to fix.
*/ */
float read_humidity(int32_t t_fine) { float read_humidity(int32_t t_fine) {
int32_t adc_value = watch_i2c_read16(BME280_ADDRESS, BME280_REGISTER_HUMID_DATA); int32_t adc_value = watch_i2c_read16(BME280_ADDRESS, BME280_REGISTER_HUMID_DATA);