samples: sensor: thermometer: add trigger support to sample

Add optional trigger support to sample. If the selected temperature sensor supports triggering using the AMBIENT_TEMP channel, then temperature thresholds will be set for +0.5 and +1.5 degrees celsius above ambient temperature. Sample overlays are provided for the FRDM_K22F board to demonstrate enabling this feature. Signed-off-by: Daniel DeGrasse <daniel@degrasse.com>
Willmish · Jun 17, 2023 · 7993e7d · 7993e7d
1 parent d382841
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diff --git a/samples/sensor/thermometer/README.rst b/samples/sensor/thermometer/README.rst
@@ -39,17 +39,31 @@ alias named ``ambient-temp0`` to link to the node.  See the overlay used for the
 ``nrf52840dk_nrf52840`` board within this sample:
 ``boards/nrf52840dk_nrf52840.overlay``
 
+
+Temperature Alert
+=================
+
+If the attached sensor supports alerts when the temperature drifts above or
+below a threshold, the sample will enable the sensor's trigger functionality.
+This will require the sensor's TRIGGER KConfig setting to be enabled. An
+example of this setup is provided for the ``frdm_k22f`` board, using
+``boards/frdm_k22f.conf``.
+
 Sample Output
 =============
 
 .. code-block:: console
 
-	*** Booting Zephyr OS build zephyr-v3.3.0-1205-g118f73e12a70 ***
-	Thermometer Example (arm)
-	Temperature device is 0x6150, name is mcp9700a
-	Temperature is 24.0°C
-	Temperature is 24.1°C
-	Temperature is 24.2°C
-	Temperature is 24.1°C
-	Temperature is 24.0°C
-	Temperature is 24.1°C
+        *** Booting Zephyr OS build zephyr-v3.3.0-2354-gb4f4bd1f1c22 ***
+        Thermometer Example (arm)
+        Temperature device is 0x525c, name is tcn75a@48
+        Set temperature lower limit to 25.5°C
+        Set temperature upper limit to 26.5°C
+        Enabled sensor threshold triggers
+        Temperature is 25.0°C
+        Temperature is 25.0°C
+        Temperature is 25.0°C
+        Temperature is 25.0°C
+        Temperature is 25.5°C
+        Temperature above threshold: 26.5°C
+        Temperature is 26.5°C
diff --git a/samples/sensor/thermometer/boards/frdm_k22f.conf b/samples/sensor/thermometer/boards/frdm_k22f.conf
@@ -0,0 +1,2 @@
+# Enable trigger support
+CONFIG_TCN75A_TRIGGER_GLOBAL_THREAD=y
diff --git a/samples/sensor/thermometer/boards/frdm_k22f.overlay b/samples/sensor/thermometer/boards/frdm_k22f.overlay
@@ -0,0 +1,24 @@
+/*
+ * Copyright 2023 Daniel DeGrasse <daniel@degrasse.com>
+ *
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+/ {
+	aliases {
+		ambient-temp0 = &temp_sensor;
+	};
+};
+
+/*
+ * Note- TCN75A is not present on the FRDM-K22F eval board, and must be
+ * wired to i2c0 and PTC2 externally
+ */
+&i2c0 {
+	temp_sensor: tcn75a@48 {
+		reg = <0x48>;
+		compatible = "microchip,tcn75a";
+		alert-gpios = <&gpioc 2 (GPIO_ACTIVE_LOW | GPIO_PULL_UP)>;
+		resolution = "10-bit";
+	};
+};
diff --git a/samples/sensor/thermometer/sample.yaml b/samples/sensor/thermometer/sample.yaml
@@ -6,4 +6,4 @@ tests:
     harness: sensor
     integration_platforms:
       - nrf52840dk_nrf52840
-    platform_allow: nrf52840dk_nrf52840
+    platform_allow: nrf52840dk_nrf52840 frdm_k22f
diff --git a/samples/sensor/thermometer/src/main.c b/samples/sensor/thermometer/src/main.c
@@ -1,6 +1,7 @@
 /*
  * Copyright (c) 2016 ARM Ltd.
  * Copyright (c) 2023 FTP Technologies
+ * Copyright (c) 2023 Daniel DeGrasse <daniel@degrasse.com>
  *
  * SPDX-License-Identifier: Apache-2.0
  */
@@ -9,11 +10,58 @@
 #include <zephyr/drivers/sensor.h>
 #include <stdio.h>
 
+static double high_temp;
+static double low_temp;
+
+int read_temperature(const struct device *dev, struct sensor_value *val)
+{
+	int ret;
+
+	ret = sensor_sample_fetch_chan(dev, SENSOR_CHAN_AMBIENT_TEMP);
+	if (ret < 0) {
+		printf("Could not fetch temperature: %d\n", ret);
+		return ret;
+	}
+
+	ret = sensor_channel_get(dev, SENSOR_CHAN_AMBIENT_TEMP, val);
+	if (ret < 0) {
+		printf("Could not get temperature: %d\n", ret);
+	}
+	return ret;
+}
+
+void temp_alert_handler(const struct device *dev, const struct sensor_trigger *trig)
+{
+	int ret;
+	struct sensor_value value;
+	double temp;
+
+	/* Read sensor value */
+	ret = read_temperature(dev, &value);
+	if (ret < 0) {
+		printf("Reading temperature failed: %d\n", ret);
+		return;
+	}
+	temp = sensor_value_to_double(&value);
+	if (temp <= low_temp) {
+		printf("Temperature below threshold: %0.1f°C\n", temp);
+	} else if (temp >= high_temp) {
+		printf("Temperature above threshold: %0.1f°C\n", temp);
+	} else {
+		printf("Error: temperature alert triggered without valid condition\n");
+	}
+}
+
 int main(void)
 {
 	const struct device *const dev = DEVICE_DT_GET(DT_ALIAS(ambient_temp0));
 	struct sensor_value value;
+	double temp;
 	int ret;
+	const struct sensor_trigger trig = {
+		.chan = SENSOR_CHAN_AMBIENT_TEMP,
+		.type = SENSOR_TRIG_THRESHOLD,
+	};
 
 	printf("Thermometer Example (%s)\n", CONFIG_ARCH);
 
@@ -24,16 +72,50 @@ int main(void)
 
 	printf("Temperature device is %p, name is %s\n", dev, dev->name);
 
-	while (1) {
-		ret = sensor_sample_fetch(dev);
-		if (ret != 0) {
-			printf("Sensor fetch failed: %d\n", ret);
-			break;
-		}
+	/* First, fetch a sensor sample to use for sensor thresholds */
+	ret = read_temperature(dev, &value);
+	if (ret != 0) {
+		printf("Failed to read temperature: %d\n", ret);
+		return ret;
+	}
+	temp = sensor_value_to_double(&value);
 
-		ret = sensor_channel_get(dev, SENSOR_CHAN_AMBIENT_TEMP, &value);
+	/* Set thresholds to +0.5 and +1.5 °C from ambient */
+	low_temp = temp + 0.5;
+	ret = sensor_value_from_double(&value, low_temp);
+	if (ret != 0) {
+		printf("Failed to convert low threshold to sensor value: %d\n", ret);
+		return ret;
+	}
+	ret = sensor_attr_set(dev, SENSOR_CHAN_AMBIENT_TEMP,
+			      SENSOR_ATTR_LOWER_THRESH, &value);
+	if (ret == 0) {
+		/* This sensor supports threshold triggers */
+		printf("Set temperature lower limit to %0.1f°C\n", low_temp);
+	}
+
+	high_temp = temp + 1.5;
+	ret = sensor_value_from_double(&value, high_temp);
+	if (ret != 0) {
+		printf("Failed to convert low threshold to sensor value: %d\n", ret);
+		return ret;
+	}
+	ret = sensor_attr_set(dev, SENSOR_CHAN_AMBIENT_TEMP,
+			      SENSOR_ATTR_UPPER_THRESH, &value);
+	if (ret == 0) {
+		/* This sensor supports threshold triggers */
+		printf("Set temperature upper limit to %0.1f°C\n", high_temp);
+	}
+
+	ret = sensor_trigger_set(dev, &trig, temp_alert_handler);
+	if (ret == 0) {
+		printf("Enabled sensor threshold triggers\n");
+	}
+
+	while (1) {
+		ret = read_temperature(dev, &value);
 		if (ret != 0) {
-			printf("Sensor get failed: %d\n", ret);
+			printf("Failed to read temperature: %d\n", ret);
 			break;
 		}
Original file line number	Diff line number	Diff line change
		@@ -0,0 +1,2 @@
		# Enable trigger support
		CONFIG_TCN75A_TRIGGER_GLOBAL_THREAD=y