1 /*
2 * Copyright (c) 2016 ARM Ltd.
3 * Copyright (c) 2023 FTP Technologies
4 * Copyright (c) 2023 Daniel DeGrasse <daniel@degrasse.com>
5 *
6 * SPDX-License-Identifier: Apache-2.0
7 */
8
9 #include <zephyr/kernel.h>
10 #include <zephyr/drivers/sensor.h>
11 #include <stdio.h>
12
13 static double high_temp;
14 static double low_temp;
15
read_temperature(const struct device * dev,struct sensor_value * val)16 int read_temperature(const struct device *dev, struct sensor_value *val)
17 {
18 int ret;
19
20 ret = sensor_sample_fetch_chan(dev, SENSOR_CHAN_AMBIENT_TEMP);
21 if (ret < 0) {
22 printf("Could not fetch temperature: %d\n", ret);
23 return ret;
24 }
25
26 ret = sensor_channel_get(dev, SENSOR_CHAN_AMBIENT_TEMP, val);
27 if (ret < 0) {
28 printf("Could not get temperature: %d\n", ret);
29 }
30 return ret;
31 }
32
temp_alert_handler(const struct device * dev,const struct sensor_trigger * trig)33 void temp_alert_handler(const struct device *dev, const struct sensor_trigger *trig)
34 {
35 int ret;
36 struct sensor_value value;
37 double temp;
38
39 /* Read sensor value */
40 ret = read_temperature(dev, &value);
41 if (ret < 0) {
42 printf("Reading temperature failed: %d\n", ret);
43 return;
44 }
45 temp = sensor_value_to_double(&value);
46 if (temp <= low_temp) {
47 printf("Temperature below threshold: %0.1f°C\n", temp);
48 } else if (temp >= high_temp) {
49 printf("Temperature above threshold: %0.1f°C\n", temp);
50 } else {
51 printf("Error: temperature alert triggered without valid condition\n");
52 }
53 }
54
main(void)55 int main(void)
56 {
57 const struct device *const dev = DEVICE_DT_GET(DT_ALIAS(ambient_temp0));
58 struct sensor_value value;
59 double temp;
60 int ret;
61 const struct sensor_trigger trig = {
62 .chan = SENSOR_CHAN_AMBIENT_TEMP,
63 .type = SENSOR_TRIG_THRESHOLD,
64 };
65
66 printf("Thermometer Example (%s)\n", CONFIG_ARCH);
67
68 if (!device_is_ready(dev)) {
69 printf("Device %s is not ready\n", dev->name);
70 return 0;
71 }
72
73 printf("Temperature device is %p, name is %s\n", dev, dev->name);
74
75 /* First, fetch a sensor sample to use for sensor thresholds */
76 ret = read_temperature(dev, &value);
77 if (ret != 0) {
78 printf("Failed to read temperature: %d\n", ret);
79 return ret;
80 }
81 temp = sensor_value_to_double(&value);
82
83 /* Set thresholds to +0.5 and +1.5 °C from ambient */
84 low_temp = temp + 0.5;
85 ret = sensor_value_from_double(&value, low_temp);
86 if (ret != 0) {
87 printf("Failed to convert low threshold to sensor value: %d\n", ret);
88 return ret;
89 }
90 ret = sensor_attr_set(dev, SENSOR_CHAN_AMBIENT_TEMP,
91 SENSOR_ATTR_LOWER_THRESH, &value);
92 if (ret == 0) {
93 /* This sensor supports threshold triggers */
94 printf("Set temperature lower limit to %0.1f°C\n", low_temp);
95 }
96
97 high_temp = temp + 1.5;
98 ret = sensor_value_from_double(&value, high_temp);
99 if (ret != 0) {
100 printf("Failed to convert low threshold to sensor value: %d\n", ret);
101 return ret;
102 }
103 ret = sensor_attr_set(dev, SENSOR_CHAN_AMBIENT_TEMP,
104 SENSOR_ATTR_UPPER_THRESH, &value);
105 if (ret == 0) {
106 /* This sensor supports threshold triggers */
107 printf("Set temperature upper limit to %0.1f°C\n", high_temp);
108 }
109
110 ret = sensor_trigger_set(dev, &trig, temp_alert_handler);
111 if (ret == 0) {
112 printf("Enabled sensor threshold triggers\n");
113 }
114
115 while (1) {
116 ret = read_temperature(dev, &value);
117 if (ret != 0) {
118 printf("Failed to read temperature: %d\n", ret);
119 break;
120 }
121
122 printf("Temperature is %0.1lf°C\n", sensor_value_to_double(&value));
123
124 k_sleep(K_MSEC(1000));
125 }
126 return 0;
127 }
128
