12-bit ADC resolution for STM32 (#20519)

Marlin/src/HAL/STM32/HAL.h

 
 #define HAL_ANALOG_SELECT(pin) pinMode(pin, INPUT)
 
-inline void HAL_adc_init() {}
-
 #define HAL_ADC_VREF         3.3
-#define HAL_ADC_RESOLUTION  10
+#define HAL_ADC_RESOLUTION  ADC_RESOLUTION // 12
 #define HAL_START_ADC(pin)  HAL_adc_start_conversion(pin)
 #define HAL_READ_ADC()      HAL_adc_result
 #define HAL_ADC_READY()     true
 
+inline void HAL_adc_init() { analogReadResolution(HAL_ADC_RESOLUTION); }
+
 void HAL_adc_start_conversion(const uint8_t adc_pin);
 
 uint16_t HAL_adc_get_result();

Marlin/src/module/thermistor/thermistors.h

 #define THERMISTOR_TABLE_SCALE (HAL_ADC_RANGE / _BV(THERMISTOR_TABLE_ADC_RESOLUTION))
 #if ENABLED(HAL_ADC_FILTERED)
   #define OVERSAMPLENR 1
+#elif HAL_ADC_RESOLUTION > 10
+  #define OVERSAMPLENR (20 - HAL_ADC_RESOLUTION)
 #else
   #define OVERSAMPLENR 16
 #endif

buildroot/share/PlatformIO/variants/MARLIN_FYSETC_S6/variant.h

 #define NUM_ANALOG_INPUTS       7
 #define NUM_ANALOG_FIRST        80
 
+#define ADC_RESOLUTION          12
+
 // PWM resolution
 // #define PWM_RESOLUTION          12
 #define PWM_FREQUENCY           20000 // >= 20 Khz => inaudible noise for fans