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drivers: sensor: ccs811: deassert WAKEn when not active

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Asserting the WAKEn increases current draw.  Turn it off when I2C is
not being used.

Signed-off-by: Peter A. Bigot <pab@pabigot.com>
Signed-off-by: Carles Cufi <carles.cufi@nordicsemi.no>
This commit is contained in:
Peter A. Bigot 2018-11-19 23:02:30 -06:00 • committed by Maureen Helm
commit cc3020ea49
1 changed files with 40 additions and 12 deletions
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52
drivers/sensor/ccs811/ccs811.c
View file

@ -19,37 +19,55 @@
LOG_MODULE_REGISTER(CCS811, CONFIG_SENSOR_LOG_LEVEL);
#ifdef DT_INST_0_AMS_CCS811_WAKE_GPIOS_CONTROLLER
static void set_wake(struct ccs811_data *drv_data, bool enable)
{
/* Always active-low */
gpio_pin_write(drv_data->gpio, DT_INST_0_AMS_CCS811_WAKE_GPIOS_PIN, !enable);
if (enable) {
k_busy_wait(50); /* t_WAKE = 50 us */
} else {
k_busy_wait(20); /* t_DWAKE = 20 us */
}
}
#else
#define set_wake(...)
#endif
static int ccs811_sample_fetch(struct device *dev, enum sensor_channel chan)
{
struct ccs811_data *drv_data = dev->driver_data;
int tries = 11;
u16_t buf[4];
u8_t status;
int rv = -EIO;
/* Check data ready flag for the measurement interval of 1 seconds */
while (tries-- > 0) {
set_wake(drv_data, true);
if (i2c_reg_read_byte(drv_data->i2c, DT_INST_0_AMS_CCS811_BASE_ADDRESS,
CCS811_REG_STATUS, &status) < 0) {
LOG_ERR("Failed to read Status register");
return -EIO;
goto out;
}
if ((status & CCS811_STATUS_DATA_READY) || tries == 0) {
break;
}
set_wake(drv_data, false);
k_sleep(K_MSEC(100));
}
if (!(status & CCS811_STATUS_DATA_READY)) {
LOG_ERR("Sensor data not available");
return -EIO;
goto out;
}
if (i2c_burst_read(drv_data->i2c, DT_INST_0_AMS_CCS811_BASE_ADDRESS,
CCS811_REG_ALG_RESULT_DATA, (u8_t *)buf, 8) < 0) {
LOG_ERR("Failed to read conversion data.");
return -EIO;
goto out;
}
drv_data->co2 = sys_be16_to_cpu(buf[0]);
@ -57,8 +75,11 @@ static int ccs811_sample_fetch(struct device *dev, enum sensor_channel chan)
drv_data->status = buf[2] & 0xff;
drv_data->error = buf[2] >> 8;
drv_data->resistance = sys_be16_to_cpu(buf[3]);
rv = 0;
return 0;
out:
set_wake(drv_data, false);
return rv;
}
static int ccs811_channel_get(struct device *dev,
@ -211,8 +232,8 @@ int ccs811_init(struct device *dev)
#ifdef DT_INST_0_AMS_CCS811_WAKE_GPIOS_PIN
gpio_pin_configure(drv_data->gpio, DT_INST_0_AMS_CCS811_WAKE_GPIOS_PIN,
GPIO_DIR_OUT);
gpio_pin_write(drv_data->gpio, DT_INST_0_AMS_CCS811_WAKE_GPIOS_PIN, 0);
set_wake(drv_data, true);
k_sleep(K_MSEC(1));
#endif
}
@ -220,19 +241,21 @@ int ccs811_init(struct device *dev)
/* Switch device to application mode */
ret = switch_to_app_mode(drv_data->i2c);
if (ret) {
return ret;
goto out;
}
/* Check Hardware ID */
if (i2c_reg_read_byte(drv_data->i2c, DT_INST_0_AMS_CCS811_BASE_ADDRESS,
CCS811_REG_HW_ID, &hw_id) < 0) {
LOG_ERR("Failed to read Hardware ID register");
return -EIO;
ret = -EIO;
goto out;
}
if (hw_id != CCS881_HW_ID) {
LOG_ERR("Hardware ID mismatch!");
return -EINVAL;
ret = -EINVAL;
goto out;
}
/* Set Measurement mode for 1 second */
@ -240,22 +263,27 @@ int ccs811_init(struct device *dev)
CCS811_REG_MEAS_MODE,
CCS811_MODE_IAQ_1SEC) < 0) {
LOG_ERR("Failed to set Measurement mode");
return -EIO;
ret = -EIO;
goto out;
}
/* Check for error */
if (i2c_reg_read_byte(drv_data->i2c, DT_INST_0_AMS_CCS811_BASE_ADDRESS,
CCS811_REG_STATUS, &status) < 0) {
LOG_ERR("Failed to read Status register");
return -EIO;
ret = -EIO;
goto out;
}
if (status & CCS811_STATUS_ERROR) {
LOG_ERR("Error occurred during sensor configuration");
return -EINVAL;
ret = -EINVAL;
goto out;
}
return 0;
out:
set_wake(drv_data, false);
return ret;
}
static struct ccs811_data ccs811_driver;