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drivers: sensor: ccs811: reset sensor when driver is initialized

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The CCS811 has a measurement lifecycle that includes certain timing
constraints, including that calibration constants should not be applied
until the conditioning period has completed.  If a device resets but the
CCS811 remains the process of inspecting current state and initializing
the device properly can be complicated.

Simplify this by forcing a reset of the device when the driver is
initialized.  Should this cause hardship the necessary logic and
infrastructure to record time-of-last-reset across reboots and verify
measurement mode/baseline consistency can be added at that point.

Signed-off-by: Peter A. Bigot <pab@pabigot.com>
This commit is contained in:
Peter A. Bigot 2018-11-21 08:37:52 -06:00 • committed by Maureen Helm
commit 21e68d4b81
1 changed files with 24 additions and 0 deletions
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24
drivers/sensor/ccs811/ccs811.c
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@ -297,6 +297,30 @@ int ccs811_init(struct device *dev)
#endif
}
/* Reset the device. This saves having to deal with detecting
* and validating any errors or configuration inconsistencies
* after a reset that left the device running.
*/
#ifdef DT_INST_0_AMS_CCS811_RESET_GPIOS_PIN
gpio_pin_write(drv_data->gpio, DT_INST_0_AMS_CCS811_RESET_GPIOS_PIN, 0);
k_busy_wait(15); /* t_RESET */
gpio_pin_write(drv_data->gpio, DT_INST_0_AMS_CCS811_RESET_GPIOS_PIN, 1);
#else
{
static u8_t const reset_seq[] = {
0xFF, 0x11, 0xE5, 0x72, 0x8A,
};
if (i2c_write(drv_data->i2c, reset_seq, sizeof(reset_seq),
DT_INST_0_AMS_CCS811_BASE_ADDRESS) < 0) {
LOG_ERR("Failed to issue SW reset");
ret = -EIO;
goto out;
}
}
#endif
k_sleep(20); /* t_START assuming recent power-on */
/* Switch device to application mode */
ret = switch_to_app_mode(drv_data->i2c);
if (ret) {