sensor: bme280: wait for sampling period before checking

Wait until the typical time that the sample would be ready before
starting to poll the status register.

Signed-off-by: Jordan Yates <[email protected]>

Author: JordanYates

drivers/sensor/bosch/bme280/bme280.c

@@ -33,6 +33,13 @@ LOG_MODULE_REGISTER(BME280, CONFIG_SENSOR_LOG_LEVEL);
  */
 #define BME280_MEASUREMENT_TIMEOUT_MS 150
 
+/* Equation 9.1, with the fractional parts rounded down */
+#define BME280_EXPECTED_SAMPLE_TIME_MS                                                             \
+	1 + BME280_TEMP_SAMPLE_TIME + BME280_PRESS_SAMPLE_TIME + BME280_HUMIDITY_SAMPLE_TIME
+
+BUILD_ASSERT(BME280_EXPECTED_SAMPLE_TIME_MS < BME280_MEASUREMENT_TIMEOUT_MS,
+	     "Expected duration over timeout duration");
+
 struct bme280_config {
 	union bme280_bus bus;
 	const struct bme280_bus_io *bus_io;
@@ -154,6 +161,7 @@ int bme280_sample_fetch_helper(const struct device *dev,
 	struct bme280_data *dev_data = dev->data;
 	uint8_t buf[8];
 	int32_t adc_press, adc_temp, adc_humidity;
+	uint32_t poll_timeout;
 	int size = 6;
 	int ret;
 
@@ -173,9 +181,14 @@ int bme280_sample_fetch_helper(const struct device *dev,
 	if (ret < 0) {
 		return ret;
 	}
+	/* Wait until the expected measurement time elapses */
+	k_sleep(K_MSEC(BME280_EXPECTED_SAMPLE_TIME_MS));
+	poll_timeout = BME280_MEASUREMENT_TIMEOUT_MS - BME280_EXPECTED_SAMPLE_TIME_MS;
+#else
+	poll_timeout = BME280_MEASUREMENT_TIMEOUT_MS;
 #endif
 
-	ret = bme280_wait_until_ready(dev, K_MSEC(BME280_MEASUREMENT_TIMEOUT_MS));
+	ret = bme280_wait_until_ready(dev, K_MSEC(poll_timeout));
 	if (ret < 0) {
 		return ret;
 	}

drivers/sensor/bosch/bme280/bme280.h

@@ -81,39 +81,54 @@ extern const struct bme280_bus_io bme280_bus_io_i2c;
 #endif
 
 #if defined CONFIG_BME280_TEMP_OVER_1X
-#define BME280_TEMP_OVER (1 << 5)
+#define BME280_TEMP_OVER        (1 << 5)
+#define BME280_TEMP_SAMPLE_TIME 2
 #elif defined CONFIG_BME280_TEMP_OVER_2X
-#define BME280_TEMP_OVER (2 << 5)
+#define BME280_TEMP_OVER        (2 << 5)
+#define BME280_TEMP_SAMPLE_TIME 4
 #elif defined CONFIG_BME280_TEMP_OVER_4X
-#define BME280_TEMP_OVER (3 << 5)
+#define BME280_TEMP_OVER        (3 << 5)
+#define BME280_TEMP_SAMPLE_TIME 8
 #elif defined CONFIG_BME280_TEMP_OVER_8X
-#define BME280_TEMP_OVER (4 << 5)
+#define BME280_TEMP_OVER        (4 << 5)
+#define BME280_TEMP_SAMPLE_TIME 16
 #elif defined CONFIG_BME280_TEMP_OVER_16X
-#define BME280_TEMP_OVER (5 << 5)
+#define BME280_TEMP_OVER        (5 << 5)
+#define BME280_TEMP_SAMPLE_TIME 32
 #endif
 
 #if defined CONFIG_BME280_PRESS_OVER_1X
-#define BME280_PRESS_OVER (1 << 2)
+#define BME280_PRESS_OVER        (1 << 2)
+#define BME280_PRESS_SAMPLE_TIME 2
 #elif defined CONFIG_BME280_PRESS_OVER_2X
-#define BME280_PRESS_OVER (2 << 2)
+#define BME280_PRESS_OVER        (2 << 2)
+#define BME280_PRESS_SAMPLE_TIME 4
 #elif defined CONFIG_BME280_PRESS_OVER_4X
-#define BME280_PRESS_OVER (3 << 2)
+#define BME280_PRESS_OVER        (3 << 2)
+#define BME280_PRESS_SAMPLE_TIME 8
 #elif defined CONFIG_BME280_PRESS_OVER_8X
-#define BME280_PRESS_OVER (4 << 2)
+#define BME280_PRESS_OVER        (4 << 2)
+#define BME280_PRESS_SAMPLE_TIME 16
 #elif defined CONFIG_BME280_PRESS_OVER_16X
-#define BME280_PRESS_OVER (5 << 2)
+#define BME280_PRESS_OVER        (5 << 2)
+#define BME280_PRESS_SAMPLE_TIME 32
 #endif
 
 #if defined CONFIG_BME280_HUMIDITY_OVER_1X
-#define BME280_HUMIDITY_OVER 1
+#define BME280_HUMIDITY_OVER        1
+#define BME280_HUMIDITY_SAMPLE_TIME 2
 #elif defined CONFIG_BME280_HUMIDITY_OVER_2X
-#define BME280_HUMIDITY_OVER 2
+#define BME280_HUMIDITY_OVER        2
+#define BME280_HUMIDITY_SAMPLE_TIME 4
 #elif defined CONFIG_BME280_HUMIDITY_OVER_4X
-#define BME280_HUMIDITY_OVER 3
+#define BME280_HUMIDITY_OVER        3
+#define BME280_HUMIDITY_SAMPLE_TIME 8
 #elif defined CONFIG_BME280_HUMIDITY_OVER_8X
-#define BME280_HUMIDITY_OVER 4
+#define BME280_HUMIDITY_OVER        4
+#define BME280_HUMIDITY_SAMPLE_TIME 16
 #elif defined CONFIG_BME280_HUMIDITY_OVER_16X
-#define BME280_HUMIDITY_OVER 5
+#define BME280_HUMIDITY_OVER        5
+#define BME280_HUMIDITY_SAMPLE_TIME 32
 #endif
 
 #if defined CONFIG_BME280_STANDBY_05MS