725-SammysHP_ADC_fix.diff

#Fixes ATTiny ADC setup/config issues
#See https://budgetlightforum.com/t/anduril-2-feature-change-suggestions/218045/467
#2023/07/05 Written [by @SammysHP on https://budgetlightforum.com/]
--- a/ToyKeeper/spaghetti-monster/fsm-adc.c
+++ b/ToyKeeper/spaghetti-monster/fsm-adc.c
@@ -83,11 +83,6 @@ inline void adc_sleep_mode() {
         // attiny1634
         set_sleep_mode(SLEEP_MODE_ADC);
     #elif defined(AVRXMEGA3)  // ATTINY816, 817, etc
-        // set the RUNSTDBY bit so ADC will run in standby mode
-        ADC0.CTRLA |= 1;
-        // set a INITDLY value because the AVR manual says so
-        // (section 30.3.5)
-        ADC0.CTRLD |= (1 << 5);
         set_sleep_mode(SLEEP_MODE_STANDBY);
     #else
         #error No ADC sleep mode defined for this hardware.
@@ -133,10 +128,10 @@ inline void ADC_on()
         ADCSRA = (1 << ADEN) | (1 << ADSC) | (1 << ADATE) | ADC_PRSCL;
         //ADCSRA |= (1 << ADSC);  // start measuring
     #elif defined(AVRXMEGA3)  // ATTINY816, 817, etc
-        set_admux_voltage();
         VREF.CTRLA |= VREF_ADC0REFSEL_1V1_gc; // Set Vbg ref to 1.1V
-        ADC0.CTRLA = ADC_ENABLE_bm | ADC_FREERUN_bm; // Enabled, free-running (aka, auto-retrigger)
-        ADC0.COMMAND |= ADC_STCONV_bm; // Start the ADC conversions    
+        ADC0.CTRLA = ADC_ENABLE_bm | ADC_FREERUN_bm | ADC_RUNSTBY_bm; // Enable ADC, free running mode, run in standby
+        ADC0.CTRLD |= ADC_INITDLY_DLY16_gc; // Delay first measurement to stabilize reference
+        set_admux_voltage();
     #else
         #error Unrecognized MCU type
     #endif