1 /*
2 * Copyright (c) 2018-2019 Peter Bigot Consulting, LLC
3 * Copyright (c) 2019 Nordic Semiconductor ASA
4 *
5 * SPDX-License-Identifier: Apache-2.0
6 */
7
8 #include <math.h>
9 #include <stdio.h>
10 #include <stdlib.h>
11
12 #include <zephyr/kernel.h>
13 #include "battery.h"
14
15 /** A discharge curve specific to the power source. */
16 static const struct battery_level_point levels[] = {
17 /* "Curve" here eyeballed from captured data for the [Adafruit
18 * 3.7v 2000 mAh](https://www.adafruit.com/product/2011) LIPO
19 * under full load that started with a charge of 3.96 V and
20 * dropped about linearly to 3.58 V over 15 hours. It then
21 * dropped rapidly to 3.10 V over one hour, at which point it
22 * stopped transmitting.
23 *
24 * Based on eyeball comparisons we'll say that 15/16 of life
25 * goes between 3.95 and 3.55 V, and 1/16 goes between 3.55 V
26 * and 3.1 V.
27 */
28
29 { 10000, 3950 },
30 { 625, 3550 },
31 { 0, 3100 },
32 };
33
now_str(void)34 static const char *now_str(void)
35 {
36 static char buf[16]; /* ...HH:MM:SS.MMM */
37 uint32_t now = k_uptime_get_32();
38 unsigned int ms = now % MSEC_PER_SEC;
39 unsigned int s;
40 unsigned int min;
41 unsigned int h;
42
43 now /= MSEC_PER_SEC;
44 s = now % 60U;
45 now /= 60U;
46 min = now % 60U;
47 now /= 60U;
48 h = now;
49
50 snprintf(buf, sizeof(buf), "%u:%02u:%02u.%03u",
51 h, min, s, ms);
52 return buf;
53 }
54
main(void)55 int main(void)
56 {
57 int rc = battery_measure_enable(true);
58
59 if (rc != 0) {
60 printk("Failed initialize battery measurement: %d\n", rc);
61 return 0;
62 }
63
64 while (true) {
65 int batt_mV = battery_sample();
66
67 if (batt_mV < 0) {
68 printk("Failed to read battery voltage: %d\n",
69 batt_mV);
70 break;
71 }
72
73 unsigned int batt_pptt = battery_level_pptt(batt_mV, levels);
74
75 printk("[%s]: %d mV; %u pptt\n", now_str(),
76 batt_mV, batt_pptt);
77
78 /* Burn battery so you can see that this works over time */
79 k_busy_wait(5 * USEC_PER_SEC);
80 }
81 printk("Disable: %d\n", battery_measure_enable(false));
82 return 0;
83 }
84
