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author | Peter Johanson <[email protected]> | 2024-03-15 21:00:37 +0000 |
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committer | Pete Johanson <[email protected]> | 2024-03-24 13:28:55 -0700 |
commit | 44358798d3dae71cc1af118e5a5bc5792f9f7761 (patch) | |
tree | 8dfea21a2073efa939962793cb28097b56001e1c | |
parent | 931a36ff4ad0b30c8165024bbfc0286d05b74b53 (diff) | |
download | zmk-44358798d3dae71cc1af118e5a5bc5792f9f7761.tar.gz zmk-44358798d3dae71cc1af118e5a5bc5792f9f7761.zip |
feat: Add ability to fetch battery voltage.
* To be able to use the Zephyr `voltage-divider` driver,
add a mode for fetching raw voltage from the sensor
and do state of charge calculation outside of the driver.
-rw-r--r-- | app/Kconfig | 14 | ||||
-rw-r--r-- | app/src/battery.c | 42 |
2 files changed, 55 insertions, 1 deletions
diff --git a/app/Kconfig b/app/Kconfig index c430bcb2d3..21e97ac635 100644 --- a/app/Kconfig +++ b/app/Kconfig @@ -383,6 +383,20 @@ config ZMK_BATTERY_REPORTING select ZMK_LOW_PRIORITY_WORK_QUEUE imply BT_BAS if ZMK_BLE +if ZMK_BATTERY_REPORTING + +choice ZMK_BATTERY_REPORTING_FETCH_MODE + prompt "Battery Reporting Fetch Mode" + +config ZMK_BATTERY_REPORTING_FETCH_MODE_STATE_OF_CHARGE + bool "State of charge" + +config ZMK_BATTERY_REPORTING_FETCH_MODE_LITHIUM_VOLTAGE + bool "Lithium Voltage" + +endchoice +endif + config ZMK_IDLE_TIMEOUT int "Milliseconds of inactivity before entering idle state (OLED shutoff, etc)" default 30000 diff --git a/app/src/battery.c b/app/src/battery.c index 1295f82248..ae79d5f794 100644 --- a/app/src/battery.c +++ b/app/src/battery.c @@ -34,11 +34,29 @@ static const struct device *const battery = DEVICE_DT_GET(DT_CHOSEN(zmk_battery) static const struct device *battery; #endif +#if IS_ENABLED(CONFIG_ZMK_BATTERY_REPORTING_FETCH_MODE_LITHIUM_VOLTAGE) +static uint8_t lithium_ion_mv_to_pct(int16_t bat_mv) { + // Simple linear approximation of a battery based off adafruit's discharge graph: + // https://learn.adafruit.com/li-ion-and-lipoly-batteries/voltages + + if (bat_mv >= 4200) { + return 100; + } else if (bat_mv <= 3450) { + return 0; + } + + return bat_mv * 2 / 15 - 459; +} + +#endif // IS_ENABLED(CONFIG_ZMK_BATTERY_REPORTING_FETCH_MODE_LITHIUM_VOLTAGE) + static int zmk_battery_update(const struct device *battery) { struct sensor_value state_of_charge; + int rc; - int rc = sensor_sample_fetch_chan(battery, SENSOR_CHAN_GAUGE_STATE_OF_CHARGE); +#if IS_ENABLED(CONFIG_ZMK_BATTERY_REPORTING_FETCH_MODE_STATE_OF_CHARGE) + rc = sensor_sample_fetch_chan(battery, SENSOR_CHAN_GAUGE_STATE_OF_CHARGE); if (rc != 0) { LOG_DBG("Failed to fetch battery values: %d", rc); return rc; @@ -50,6 +68,28 @@ static int zmk_battery_update(const struct device *battery) { LOG_DBG("Failed to get battery state of charge: %d", rc); return rc; } +#elif IS_ENABLED(CONFIG_ZMK_BATTERY_REPORTING_FETCH_MODE_LITHIUM_VOLTAGE) + rc = sensor_sample_fetch_chan(battery, SENSOR_CHAN_VOLTAGE); + if (rc != 0) { + LOG_DBG("Failed to fetch battery values: %d", rc); + return rc; + } + + struct sensor_value voltage; + rc = sensor_channel_get(battery, SENSOR_CHAN_VOLTAGE, &voltage); + + if (rc != 0) { + LOG_DBG("Failed to get battery voltage: %d", rc); + return rc; + } + + uint16_t mv = voltage.val1 * 1000 + (voltage.val2 / 1000); + state_of_charge.val1 = lithium_ion_mv_to_pct(mv); + + LOG_DBG("State of change %d from %d mv", state_of_charge.val1, mv); +#else +#error "Not a supported reporting fetch mode" +#endif if (last_state_of_charge != state_of_charge.val1) { last_state_of_charge = state_of_charge.val1; |