drivers/sensor: sht3xd: implement single shot mode

For now there is only periodic data acquisition mode implemented. This mode is quite power consuming. Based on datasheet in idle state in periodic data acquisition mode SHT3X consumes 45uA but in single shot mode 0.2uA. For many applications where power consumption has to be kept as low as possible single shot mode is the only choice. Tester on custom board NRF52832 + SHT31-DIS. Signed-off-by: Michał Oleszczyk <[email protected]>
mlaz · Sep 18, 2019 · da4d00e · da4d00e
1 parent 1593de9
commit da4d00e
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Showing 2 changed files with 42 additions and 1 deletion.
diff --git a/drivers/sensor/sht3xd/Kconfig b/drivers/sensor/sht3xd/Kconfig
@@ -70,6 +70,20 @@ config SHT3XD_REPEATABILITY_HIGH
 
 endchoice
 
+choice
+	prompt "Measurement mode"
+	default SHT3XD_PERIODIC_MODE
+
+config SHT3XD_SINGLE_SHOT_MODE
+	bool "single shot"
+
+config SHT3XD_PERIODIC_MODE
+	bool "periodic data acquisition"
+
+endchoice
+
+if SHT3XD_PERIODIC_MODE
+
 choice
 	prompt "Measurements per second"
 	default SHT3XD_MPS_1
@@ -93,4 +107,6 @@ config SHT3XD_MPS_10
 
 endchoice
 
+endif # SHT3XD_PERIODIC_MODE
+
 endif # SHT3XD
diff --git a/drivers/sensor/sht3xd/sht3xd.c b/drivers/sensor/sht3xd/sht3xd.c
@@ -16,13 +16,20 @@
 #define LOG_LEVEL CONFIG_SENSOR_LOG_LEVEL
 LOG_MODULE_REGISTER(SHT3XD);
 
+#ifdef CONFIG_SHT3XD_SINGLE_SHOT_MODE
+static const u16_t measure_cmd[3] = {
+	0x2400, 0x240B, 0x2416
+};
+#endif
+#ifdef CONFIG_SHT3XD_PERIODIC_MODE
 static const u16_t measure_cmd[5][3] = {
 	{ 0x202F, 0x2024, 0x2032 },
 	{ 0x212D, 0x2126, 0x2130 },
 	{ 0x222B, 0x2220, 0x2236 },
 	{ 0x2329, 0x2322, 0x2334 },
 	{ 0x272A, 0x2721, 0x2737 }
 };
+#endif
 
 static const int measure_wait[3] = {
 	4000, 6000, 15000
@@ -85,6 +92,22 @@ static int sht3xd_sample_fetch(struct device *dev, enum sensor_channel chan)
 
 	__ASSERT_NO_MSG(chan == SENSOR_CHAN_ALL);
 
+#ifdef CONFIG_SHT3XD_SINGLE_SHOT_MODE
+	/* start single shot measurement */
+	if (sht3xd_write_command(dev,
+				 measure_cmd[SHT3XD_REPEATABILITY_IDX])
+	    < 0) {
+		LOG_DBG("Failed to set single shot measurement mode!");
+		return -EIO;
+	}
+	k_sleep(K_MSEC(measure_wait[SHT3XD_REPEATABILITY_IDX] / USEC_PER_MSEC));
+
+	if (i2c_read(i2c, rx_buf, sizeof(rx_buf), address) < 0) {
+		LOG_DBG("Failed to read data sample!");
+		return -EIO;
+	}
+#endif
+#ifdef CONFIG_SHT3XD_PERIODIC_MODE
 	u8_t tx_buf[2] = {
 		SHT3XD_CMD_FETCH >> 8,
 		SHT3XD_CMD_FETCH & 0xFF
@@ -95,6 +118,7 @@ static int sht3xd_sample_fetch(struct device *dev, enum sensor_channel chan)
 		LOG_DBG("Failed to read data sample!");
 		return -EIO;
 	}
+#endif
 
 	t_sample = (rx_buf[0] << 8) | rx_buf[1];
 	if (sht3xd_compute_crc(t_sample) != rx_buf[2]) {
@@ -179,6 +203,7 @@ static int sht3xd_init(struct device *dev)
 
 	k_busy_wait(SHT3XD_CLEAR_STATUS_WAIT_USEC);
 
+#ifdef CONFIG_SHT3XD_PERIODIC_MODE
 	/* set periodic measurement mode */
 	if (sht3xd_write_command(dev,
 				 measure_cmd[SHT3XD_MPS_IDX][SHT3XD_REPEATABILITY_IDX])
@@ -188,7 +213,7 @@ static int sht3xd_init(struct device *dev)
 	}
 
 	k_busy_wait(measure_wait[SHT3XD_REPEATABILITY_IDX]);
-
+#endif
 #ifdef CONFIG_SHT3XD_TRIGGER
 	if (sht3xd_init_interrupt(dev) < 0) {
 		LOG_DBG("Failed to initialize interrupt");