1 /*
2 * Copyright (c) 2020 Libre Solar Technologies GmbH
3 *
4 * SPDX-License-Identifier: Apache-2.0
5 */
6
7 #include <zephyr/kernel.h>
8 #include <zephyr/sys/printk.h>
9 #include <zephyr/drivers/dac.h>
10
11 #define ZEPHYR_USER_NODE DT_PATH(zephyr_user)
12
13 #if (DT_NODE_HAS_PROP(ZEPHYR_USER_NODE, dac) && \
14 DT_NODE_HAS_PROP(ZEPHYR_USER_NODE, dac_channel_id) && \
15 DT_NODE_HAS_PROP(ZEPHYR_USER_NODE, dac_resolution))
16 #define DAC_NODE DT_PHANDLE(ZEPHYR_USER_NODE, dac)
17 #define DAC_CHANNEL_ID DT_PROP(ZEPHYR_USER_NODE, dac_channel_id)
18 #define DAC_RESOLUTION DT_PROP(ZEPHYR_USER_NODE, dac_resolution)
19 #else
20 #error "Unsupported board: see README and check /zephyr,user node"
21 #define DAC_NODE DT_INVALID_NODE
22 #define DAC_CHANNEL_ID 0
23 #define DAC_RESOLUTION 0
24 #endif
25
26 static const struct device *const dac_dev = DEVICE_DT_GET(DAC_NODE);
27
28 static const struct dac_channel_cfg dac_ch_cfg = {
29 .channel_id = DAC_CHANNEL_ID,
30 .resolution = DAC_RESOLUTION,
31 .buffered = true
32 };
33
main(void)34 int main(void)
35 {
36 if (!device_is_ready(dac_dev)) {
37 printk("DAC device %s is not ready\n", dac_dev->name);
38 return 0;
39 }
40
41 int ret = dac_channel_setup(dac_dev, &dac_ch_cfg);
42
43 if (ret != 0) {
44 printk("Setting up of DAC channel failed with code %d\n", ret);
45 return 0;
46 }
47
48 printk("Generating sawtooth signal at DAC channel %d.\n",
49 DAC_CHANNEL_ID);
50 while (1) {
51 /* Number of valid DAC values, e.g. 4096 for 12-bit DAC */
52 const int dac_values = 1U << DAC_RESOLUTION;
53
54 /*
55 * 1 msec sleep leads to about 4 sec signal period for 12-bit
56 * DACs. For DACs with lower resolution, sleep time needs to
57 * be increased.
58 * Make sure to sleep at least 1 msec even for future 16-bit
59 * DACs (lowering signal frequency).
60 */
61 const int sleep_time = 4096 / dac_values > 0 ?
62 4096 / dac_values : 1;
63
64 for (int i = 0; i < dac_values; i++) {
65 ret = dac_write_value(dac_dev, DAC_CHANNEL_ID, i);
66 if (ret != 0) {
67 printk("dac_write_value() failed with code %d\n", ret);
68 return 0;
69 }
70 k_sleep(K_MSEC(sleep_time));
71 }
72 }
73 return 0;
74 }
75
