1 /*
2 * Copyright (c) 2021 Leonard Pollak
3 *
4 * SPDX-License-Identifier: Apache-2.0
5 */
6
7 #include <zephyr/kernel.h>
8 #include <zephyr/device.h>
9 #include <zephyr/drivers/sensor.h>
10 #include <stdio.h>
11
12 #include <zephyr/drivers/sensor/sgp40.h>
13 #include <zephyr/drivers/sensor/sht4x.h>
14
15 #if !DT_HAS_COMPAT_STATUS_OKAY(sensirion_sgp40)
16 #error "No sensirion,sgp40 compatible node found in the device tree"
17 #endif
18
19 #if !DT_HAS_COMPAT_STATUS_OKAY(sensirion_sht4x)
20 #error "No sensirion,sht4x compatible node found in the device tree"
21 #endif
22
main(void)23 int main(void)
24 {
25
26 #if CONFIG_APP_USE_COMPENSATION
27 struct sensor_value comp_t;
28 struct sensor_value comp_rh;
29 #endif
30 const struct device *const sht = DEVICE_DT_GET_ANY(sensirion_sht4x);
31 const struct device *const sgp = DEVICE_DT_GET_ANY(sensirion_sgp40);
32 struct sensor_value temp, hum, gas;
33
34 if (!device_is_ready(sht)) {
35 printf("Device %s is not ready.\n", sht->name);
36 return 0;
37 }
38
39 if (!device_is_ready(sgp)) {
40 printf("Device %s is not ready.\n", sgp->name);
41 return 0;
42 }
43
44 #if CONFIG_APP_USE_HEATER
45 struct sensor_value heater_p;
46 struct sensor_value heater_d;
47
48 heater_p.val1 = CONFIG_APP_HEATER_PULSE_POWER;
49 heater_d.val1 = CONFIG_APP_HEATER_PULSE_DURATION;
50 sensor_attr_set(sht, SENSOR_CHAN_ALL,
51 SENSOR_ATTR_SHT4X_HEATER_POWER, &heater_p);
52 sensor_attr_set(sht, SENSOR_CHAN_ALL,
53 SENSOR_ATTR_SHT4X_HEATER_DURATION, &heater_d);
54 #endif
55
56 while (true) {
57
58 if (sensor_sample_fetch(sht)) {
59 printf("Failed to fetch sample from SHT4X device\n");
60 return 0;
61 }
62
63 sensor_channel_get(sht, SENSOR_CHAN_AMBIENT_TEMP, &temp);
64 sensor_channel_get(sht, SENSOR_CHAN_HUMIDITY, &hum);
65 #if CONFIG_APP_USE_HEATER
66 /*
67 * Conditions in which it makes sense to activate the heater
68 * are application/environment specific.
69 *
70 * The heater should not be used above SHT4X_HEATER_MAX_TEMP (65 °C)
71 * as stated in the datasheet.
72 *
73 * The temperature data will not be updated here for obvious reasons.
74 **/
75 if (hum.val1 > CONFIG_APP_HEATER_HUMIDITY_THRESH &&
76 temp.val1 < SHT4X_HEATER_MAX_TEMP) {
77 printf("Activating heater.\n");
78
79 if (sht4x_fetch_with_heater(sht)) {
80 printf("Failed to fetch sample from SHT4X device\n");
81 return 0;
82 }
83
84 sensor_channel_get(sht, SENSOR_CHAN_HUMIDITY, &hum);
85 }
86 #endif
87
88 #if CONFIG_APP_USE_COMPENSATION
89 comp_t.val1 = temp.val1; /* Temp [°C] */
90 comp_rh.val1 = hum.val1; /* RH [%] */
91 sensor_attr_set(sgp,
92 SENSOR_CHAN_GAS_RES,
93 SENSOR_ATTR_SGP40_TEMPERATURE,
94 &comp_t);
95 sensor_attr_set(sgp,
96 SENSOR_CHAN_GAS_RES,
97 SENSOR_ATTR_SGP40_HUMIDITY,
98 &comp_rh);
99 #endif
100 if (sensor_sample_fetch(sgp)) {
101 printf("Failed to fetch sample from SGP40 device.\n");
102 return 0;
103 }
104
105 sensor_channel_get(sgp, SENSOR_CHAN_GAS_RES, &gas);
106
107 printf("SHT4X: %.2f Temp. [C] ; %0.2f RH [%%] -- SGP40: %d Gas [a.u.]\n",
108 sensor_value_to_double(&temp),
109 sensor_value_to_double(&hum),
110 gas.val1);
111
112 /* Maximum duty cycle for using the heater is 5% */
113 #if CONFIG_APP_USE_HEATER && CONFIG_APP_HEATER_PULSE_DURATION == 0
114 k_sleep(K_MSEC(20000));
115 #else
116 k_sleep(K_MSEC(2000));
117 #endif
118 }
119 }
120
