From 15fd31a6ce18b7c04d64e864df30a8afe73b11ed6a9409742f4539930b00be43 Mon Sep 17 00:00:00 2001
From: localhorst <localhorst@mosad.xyz>
Date: Sun, 9 Nov 2025 18:56:56 +0100
Subject: [PATCH] some tries to get adc bat refernce

---
 main.c | 58 +++++++++++++++++++++++++++++++++++++++++-----------------
 1 file changed, 41 insertions(+), 17 deletions(-)

diff --git a/main.c b/main.c
index b9cb86b..f8f454e 100644
--- a/main.c
+++ b/main.c
@@ -26,6 +26,7 @@
 #define BUTTON_CONFIRMATION_BLINK_DURATION_MS 50U
 #define GLOW_BRIGHTNESS_MIN 10U
 #define GLOW_BRIGHTNESS_MAX 100U
+#define INTERNAL_VREF_MV 1024UL
 
 /** Convert milliseconds to system ticks */
 #define MS_TO_TICKS(ms) ((ms) / MAIN_LOOP_SLEEP)
@@ -75,7 +76,7 @@ int main(void)
     VPORTA.DIR &= ~BUTTON_PIN_MASK;    // Input
     PORTA.PIN0CTRL = PORT_PULLUPEN_bm; // Pull-up enabled
 
-    leds_off();                // Ensure all LEDs off at startup
+    leds_off(); // Ensure all LEDs off at startup
 
     bool bLedEnabledOld = bLedEnabled;
     eModeCurrent = ANIMATION_BLINK; // Set the mode to start with
@@ -255,31 +256,46 @@ static inline void leds_on(void)
  */
 uint16_t readBatteryVoltage(void)
 {
-    // Enable ADC
-    ADC0.CTRLA = ADC_ENABLE_bm;
+    // Enable ADC with proper configuration
+    ADC0.CTRLC = ADC_REFSEL_VDDREF_gc | // VCC as reference
+                 ADC_PRESC_DIV4_gc;     // Prescaler DIV4
 
-    // Select internal voltage reference as input
+    // 10-bit resolution (default)
+    ADC0.CTRLA = ADC_RESSEL_10BIT_gc;
+
+    // Select internal voltage reference as input to measure
     ADC0.MUXPOS = ADC_MUXPOS_INTREF_gc;
 
-    // Use VCC as reference (default)
-    ADC0.CTRLC = ADC_PRESC_DIV4_gc; // Prescaler for 5MHz/4 = 1.25MHz ADC clock
+    // Enable ADC
+    ADC0.CTRLA |= ADC_ENABLE_bm;
 
-    // Start conversion
+    // Wait for ADC to stabilize
+    _delay_us(100);
+
+    // Dummy conversion for stability
     ADC0.COMMAND = ADC_STCONV_bm;
+    while (!(ADC0.INTFLAGS & ADC_RESRDY_bm))
+        ;
+    ADC0.INTFLAGS = ADC_RESRDY_bm; // Clear flag
 
-    // Wait for conversion complete
+    // Actual conversion
+    ADC0.COMMAND = ADC_STCONV_bm;
     while (!(ADC0.INTFLAGS & ADC_RESRDY_bm))
         ;
 
     uint16_t adcResult = ADC0.RES;
 
     // Disable ADC to save power
-    ADC0.CTRLA = !ADC_ENABLE_bm;
+    ADC0.CTRLA |= !ADC_ENABLE_bm;
 
-    // Calculate VCC voltage
-    // V_battery = 1.1V × 1023 / ADC_result
-    // Result in millivolts: 1100 × 1023 / ADC_result
-    uint32_t voltage_mv = (1100UL * 1023UL) / adcResult;
+    // Check for valid reading
+    if (adcResult == 0 || adcResult >= 1023)
+    {
+        return 0; // Invalid reading
+    }
+
+    // Calculate VCC: V_VCC = VREF × 1023 / ADC_result
+    uint32_t voltage_mv = (INTERNAL_VREF_MV * 1023 / adcResult);
 
     return (uint16_t)voltage_mv;
 }
@@ -293,9 +309,18 @@ static void battery_level_indicator(void)
 
     // 1S LiPo voltage ranges:
     // Good: >=3700mV
-    // Low:  >=3500mV
+    // Low:  >=3500mV --> 
 
-   // VPORTA.OUT &= ~(PA6_SET_MASK | PA7_SET_MASK); // Turn off both LEDs first
+    // VPORTA.OUT &= ~(PA6_SET_MASK | PA7_SET_MASK); // Turn off both LEDs first
+    VPORTA.OUT |= (PA6_SET_MASK | PA7_SET_MASK); // Red Debug ON
+
+    if (voltage <= 65534)
+    {
+        // Green OFF, Red ON - Low battery
+        //VPORTA.OUT &= ~PA7_SET_MASK; // Red Debug OFF
+    }
+
+    return;
 
     if (voltage >= 3700)
     {
@@ -312,9 +337,8 @@ static void battery_level_indicator(void)
         // Green OFF, Red ON - Low battery
         VPORTA.OUT &= ~PA7_SET_MASK; // Red ON (active low)
     }
-
-    VPORTA.OUT &= ~(PA6_SET_MASK | PA7_SET_MASK);
 }
+
 /**
  * @brief Handle momentary switch input on PA0
  *