From ea8bf0b936615dd7afe85dd6266a17afbd8921b4 Mon Sep 17 00:00:00 2001
From: Donald Gordon <donald@gordon.nz>
Date: Wed, 28 Sep 2022 21:11:04 +0900
Subject: [PATCH] RGB underglow: dim or disable when battery low

Disable underglow when battery below 10%, halve brightness when battery below 20%
---
 app/src/rgb_underglow.c | 32 ++++++++++++++++++++++++++++++++
 1 file changed, 32 insertions(+)

diff --git a/app/src/rgb_underglow.c b/app/src/rgb_underglow.c
index 65b19d59..b4621e82 100644
--- a/app/src/rgb_underglow.c
+++ b/app/src/rgb_underglow.c
@@ -185,6 +185,7 @@ static void zmk_led_write_pixels() {
     static struct led_rgb led_buffer[STRIP_NUM_PIXELS];
     int bat0 = zmk_battery_state_of_charge();
     int blend = 0;
+    int reset_ext_power = 0;
     if (state.status_active) {
         blend = zmk_led_generate_status();
     }
@@ -194,6 +195,18 @@ static void zmk_led_write_pixels() {
         led_strip_update_rgb(led_strip, pixels, STRIP_NUM_PIXELS);
         return;
     }
+    // battery below minimum charge
+    if (bat0 < 10) {
+        memset(pixels, 0, sizeof(struct led_rgb) * STRIP_NUM_PIXELS);
+        if (state.on) {
+            int c_power = ext_power_get(ext_power);
+            if (c_power && !state.status_active) {
+                // power is on, RGB underglow is on, but battery is too low
+                state.on = false;
+                reset_ext_power = true;
+            }
+        }
+    }
 
     if (blend == 0) {
         for (int i = 0; i < STRIP_NUM_PIXELS; i++) {
@@ -216,7 +229,20 @@ static void zmk_led_write_pixels() {
         }
     }
 
+    // battery below 20%, reduce LED brightness
+    if (bat0 < 20) {
+        for (int i = 0; i < STRIP_NUM_PIXELS; i++) {
+            led_buffer[i].r = led_buffer[i].r >> 1;
+            led_buffer[i].g = led_buffer[i].g >> 1;
+            led_buffer[i].b = led_buffer[i].b >> 1;
+        }
+    }
+
     led_strip_update_rgb(led_strip, led_buffer, STRIP_NUM_PIXELS);
+
+    if (reset_ext_power) {
+        zmk_rgb_set_ext_power();
+    }
 }
 
 #define UNDERGLOW_INDICATORS DT_PATH(underglow_indicators)
@@ -485,6 +511,12 @@ int zmk_rgb_set_ext_power() {
         c_power = 0;
     }
     int desired_state = state.on || state.status_active;
+    // force power off, when battery low (<10%)
+    if (state.on && !state.status_active) {
+        if (zmk_battery_state_of_charge() < 10) {
+            desired_state = false;
+        }
+    }
     if (desired_state && !c_power) {
         int rc = ext_power_enable(ext_power);
         if (rc != 0) {