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powermgmt: Better time estimation

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This method, while far from perfect, is able to make use of
real-time battery usage information and updates frequently
in fine-grained increments. This should make time estimates
a lot more useful than they previously were.

Change-Id: I66c6daba88210f60a27e239fbbcc56869be3b878
This commit is contained in:
Aidan MacDonald 2021-12-23 02:49:50 +00:00
parent 90dd2f84a9
commit 96cfe329a6
2 changed files with 50 additions and 16 deletions
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4
firmware/export/powermgmt.h
View file

@ -95,8 +95,8 @@ void powermgmt_init(void) INIT_ATTR;
#endif
#ifndef BATT_CURRENT_AVE_SAMPLES
/* TODO may need tweaking */
#define BATT_CURRENT_AVE_SAMPLES 16
/* semi arbitrary but needs to be 'large' for the time estimation algorithm */
#define BATT_CURRENT_AVE_SAMPLES 128
#endif
#ifndef POWER_THREAD_STEP_TICKS

62
firmware/powermgmt.c
View file

@ -102,6 +102,13 @@ static char power_stack[DEFAULT_STACK_SIZE/2];
#endif
static const char power_thread_name[] = "power";
/* Time estimation requires 64 bit math so don't use it in the bootloader.
* Also we need to be able to measure current, and not have a better time
* estimate source available. */
#define HAVE_TIME_ESTIMATION \
(!defined(BOOTLOADER) && !(CONFIG_BATTERY_MEASURE & TIME_MEASURE) && \
(defined(CURRENT_NORMAL) || (CONFIG_BATTERY_MEASURE & CURRENT_MEASURE)))
#if !(CONFIG_BATTERY_MEASURE & PERCENTAGE_MEASURE)
int _battery_level(void) { return -1; }
#endif
@ -109,12 +116,16 @@ static int percent_now; /* Cached to avoid polling too often */
#if !(CONFIG_BATTERY_MEASURE & TIME_MEASURE)
int _battery_time(void) { return -1; }
#endif
#if (CONFIG_BATTERY_MEASURE & TIME_MEASURE) || \
defined(CURRENT_NORMAL) || (CONFIG_BATTERY_MEASURE & CURRENT_MEASURE)
#else
static int time_now; /* Cached to avoid polling too often */
#endif
#if HAVE_TIME_ESTIMATION
static int time_now; /* reported time in minutes */
static int64_t time_cnt; /* reported time in seconds */
static int64_t time_err; /* error... it's complicated */
#endif
#if !(CONFIG_BATTERY_MEASURE & VOLTAGE_MEASURE)
int _battery_voltage(void) { return -1; }
#else
@ -149,8 +160,7 @@ int battery_level(void)
* on the battery level and the actual current usage. */
int battery_time(void)
{
#if (CONFIG_BATTERY_MEASURE & TIME_MEASURE) || \
defined(CURRENT_NORMAL) || (CONFIG_BATTERY_MEASURE & CURRENT_MEASURE)
#if (CONFIG_BATTERY_MEASURE & TIME_MEASURE) || HAVE_TIME_ESTIMATION
return time_now;
#else
return -1;
@ -373,19 +383,43 @@ static void battery_status_update(void)
#if CONFIG_BATTERY_MEASURE & TIME_MEASURE
time_now = _battery_time();
#elif defined(CURRENT_NORMAL) || (CONFIG_BATTERY_MEASURE & CURRENT_MEASURE)
#elif HAVE_TIME_ESTIMATION
/* TODO: This is essentially a bad version of coloumb counting,
* so in theory using coloumb counters when they are available
* should provide a more accurate result. Also note that this
* is hard-coded with a HZ/2 update rate to simplify arithmetic. */
int current = battery_current();
if(level >= 0 && current > 0 && battery_capacity > 0) {
int resolution = battery_capacity * 36;
int time_est;
#if CONFIG_CHARGING >= CHARGING_MONITOR
if (charging_state())
time_now = (100 - level) * battery_capacity * 60 / 100 / current;
else
if (charging_state())
time_est = (100 - level) * battery_capacity * 36 / current;
else
#endif
time_now = (level + percent_now) * battery_capacity * 60 / 200 / current;
} else {
/* not enough information to calculate time remaining */
time_now = -1;
time_est = level * battery_capacity * 36 / current;
/* The first term nudges the counter toward the estimate.
* The second term decrements the counter due to elapsed time. */
time_err += current * (time_est - time_cnt);
time_err -= resolution;
/* Arbitrary cutoff to ensure we don't get too far out
* of sync. Seems to work well on synthetic tests. */
if(time_err > resolution * 12 ||
time_err < -resolution * 13) {
time_cnt = time_est;
time_err = 0;
}
/* Convert the error into a time and adjust the counter. */
int64_t adjustment = time_err / (2 * resolution);
time_cnt += adjustment;
time_err -= adjustment * (2 * resolution);
/* Update the reported time based on the counter. */
time_now = (time_cnt + 30) / 60;
#endif
percent_now = level;