fix(adc): Always use default read resolution in __analogReadMilliVolts to obtain correct milliVolts value. (espressif#9006)

Add new __analogReadRaw function and move code from __analogRead without mapResolution part to __analogReadRaw.

Refactor __anlogRead to use analogReadRaw (and mapResolution).

Refactor __analogReadMilliVolts to always use default read resolution when reading adc value, as expected input by esp_adc_cal_raw_to_voltage is in default resolution (means replacing all calls of __analogRead with __analogReadRaw).

Author: bkari02

Diff for: cores/esp32/esp32-hal-adc.c

@@ -149,7 +149,7 @@ void __analogReadResolution(uint8_t bits)
 #endif
 }
 
-uint16_t __analogRead(uint8_t pin)
+uint16_t __analogReadRaw(uint8_t pin)
 {
     int8_t channel = digitalPinToAnalogChannel(pin);
     int value = 0;
@@ -173,8 +173,14 @@ uint16_t __analogRead(uint8_t pin)
         }
     } else {
         value = adc1_get_raw(channel);
-        return mapResolution(value);
+        return value;
     }
+    return value;
+}
+
+uint16_t __analogRead(uint8_t pin)
+{
+    uint16_t value = __analogReadRaw(pin);
     return mapResolution(value);
 }
 
@@ -201,7 +207,7 @@ uint32_t __analogReadMilliVolts(uint8_t pin){
             if(__analogVRefPin){
                 esp_adc_cal_characteristics_t chars;
                 if(adc_vref_to_gpio(ADC_UNIT_2, __analogVRefPin) == ESP_OK){
-                    __analogVRef = __analogRead(__analogVRefPin);
+                    __analogVRef = __analogReadRaw(__analogVRefPin);
                     esp_adc_cal_characterize(1, __analogAttenuation, __analogWidth, DEFAULT_VREF, &chars);
                     __analogVRef = esp_adc_cal_raw_to_voltage(__analogVRef, &chars);
                     log_d("Vref to GPIO%u: %u", __analogVRefPin, __analogVRef);
@@ -215,7 +221,7 @@ uint32_t __analogReadMilliVolts(uint8_t pin){
         unit = 2;
     }
 
-    uint16_t adc_reading = __analogRead(pin);
+    uint16_t adc_reading = __analogReadRaw(pin);
 
     uint8_t atten = __analogAttenuation;
     if (__pin_attenuation[pin] != ADC_ATTENDB_MAX){
@@ -266,6 +272,7 @@ int __hallRead()    //hall sensor using idf read
 #endif
 
 extern uint16_t analogRead(uint8_t pin) __attribute__ ((weak, alias("__analogRead")));
+extern uint16_t analogReadRaw(uint8_t pin) __attribute__ ((weak, alias("__analogReadRaw")));
 extern uint32_t analogReadMilliVolts(uint8_t pin) __attribute__ ((weak, alias("__analogReadMilliVolts")));
 extern void analogReadResolution(uint8_t bits) __attribute__ ((weak, alias("__analogReadResolution")));
 extern void analogSetClockDiv(uint8_t clockDiv) __attribute__ ((weak, alias("__analogSetClockDiv")));

Diff for: cores/esp32/esp32-hal-adc.h

@@ -39,6 +39,11 @@ typedef enum {
  * */
 uint16_t analogRead(uint8_t pin);
 
+/*
+ * Get ADC value in default resolution for pin
+ * */
+uint16_t analogReadRaw(uint8_t pin);
+
 /*
  * Get MilliVolts value for pin
  * */