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sensor: si7006: combined RH/T measurements

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The Si7006-A20 rev. 1.2 datasheet, section 5.1.2. Measuring Temperature
says that:

"Each time a relative humidity measurement is made a temperature
measurement is also made for the purposes of temperature compensation of
the relative humidity measurement. If the temperature value is required,
it can be read using command 0xE0; this avoids having to perform a
second temperature measurement."

Respective improvement is implemented.

Signed-off-by: Max Payne <forgge@gmail.com>
Signed-off-by: Anthony Brandon <anthony@amarulasolutions.com>
This commit is contained in:
Anthony Brandon 2020-04-21 16:59:32 +02:00 • committed by Maureen Helm
commit 7dd4cc5821
1 changed files with 8 additions and 5 deletions
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13
drivers/sensor/si7006/si7006.c
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@ -54,17 +54,20 @@ static int si7006_get_humidity(struct device *i2c_dev,
/** /**
* @brief function to get temperature * @brief function to get temperature
* *
* Note that si7006_get_humidity must be called before calling
* si7006_get_old_temperature.
*
* @return int 0 on success * @return int 0 on success
*/ */
static int si7006_get_temperature(struct device *i2c_dev, static int si7006_get_old_temperature(struct device *i2c_dev,
struct si7006_data *si_data) struct si7006_data *si_data)
{ {
u8_t temp[2]; u8_t temp[2];
int retval; int retval;
retval = i2c_burst_read(i2c_dev, DT_INST_REG_ADDR(0), retval = i2c_burst_read(i2c_dev, DT_INST_REG_ADDR(0),
SI7006_MEAS_TEMP_MASTER_MODE, temp, sizeof(temp)); SI7006_READ_OLD_TEMP, temp, sizeof(temp));
if (retval == 0) { if (retval == 0) {
si_data->temperature = (temp[0] << 8) | temp[1]; si_data->temperature = (temp[0] << 8) | temp[1];
@ -85,9 +88,9 @@ static int si7006_sample_fetch(struct device *dev, enum sensor_channel chan)
int retval; int retval;
struct si7006_data *si_data = dev->driver_data; struct si7006_data *si_data = dev->driver_data;
retval = si7006_get_temperature(si_data->i2c_dev, si_data); retval = si7006_get_humidity(si_data->i2c_dev, si_data);
if (retval == 0) { if (retval == 0) {
retval = si7006_get_humidity(si_data->i2c_dev, si_data); retval = si7006_get_old_temperature(si_data->i2c_dev, si_data);
} }
return retval; return retval;