ESP32 HAL - Dynamic ADC attenuation (#14623)

Marlin/src/HAL/HAL_ESP32/HAL.cpp

@@ -67,7 +67,9 @@ uint16_t HAL_adc_result;
 // Private Variables
 // ------------------------
 
-esp_adc_cal_characteristics_t characteristics;
+esp_adc_cal_characteristics_t characteristics[ADC_ATTEN_MAX];
+adc_atten_t attenuations[ADC1_CHANNEL_MAX] = {};
+uint32_t thresholds[ADC_ATTEN_MAX];
 volatile int numPWMUsed = 0,
              pwmPins[MAX_PWM_PINS],
              pwmValues[MAX_PWM_PINS];
@@ -129,49 +131,74 @@ adc1_channel_t get_channel(int pin) {
   return ADC1_CHANNEL_MAX;
 }
 
+void adc1_set_attenuation(adc1_channel_t chan, adc_atten_t atten) {
+  if (attenuations[chan] != atten) {
+    adc1_config_channel_atten(chan, atten);
+    attenuations[chan] = atten;
+  }
+}
+
 void HAL_adc_init() {
   // Configure ADC
   adc1_config_width(ADC_WIDTH_12Bit);
 
   // Configure channels only if used as (re-)configuring a pin for ADC that is used elsewhere might have adverse effects
   #if HAS_TEMP_ADC_0
-    adc1_config_channel_atten(get_channel(TEMP_0_PIN), ADC_ATTEN_11db);
+    adc1_set_attenuation(get_channel(TEMP_0_PIN), ADC_ATTEN_11db);
   #endif
   #if HAS_TEMP_ADC_1
-    adc1_config_channel_atten(get_channel(TEMP_1_PIN), ADC_ATTEN_11db);
+    adc1_set_attenuation(get_channel(TEMP_1_PIN), ADC_ATTEN_11db);
   #endif
   #if HAS_TEMP_ADC_2
-    adc1_config_channel_atten(get_channel(TEMP_2_PIN), ADC_ATTEN_11db);
+    adc1_set_attenuation(get_channel(TEMP_2_PIN), ADC_ATTEN_11db);
   #endif
   #if HAS_TEMP_ADC_3
-    adc1_config_channel_atten(get_channel(TEMP_3_PIN), ADC_ATTEN_11db);
+    adc1_set_attenuation(get_channel(TEMP_3_PIN), ADC_ATTEN_11db);
   #endif
   #if HAS_TEMP_ADC_4
-    adc1_config_channel_atten(get_channel(TEMP_4_PIN), ADC_ATTEN_11db);
+    adc1_set_attenuation(get_channel(TEMP_4_PIN), ADC_ATTEN_11db);
   #endif
   #if HAS_TEMP_ADC_5
-    adc1_config_channel_atten(get_channel(TEMP_5_PIN), ADC_ATTEN_11db);
+    adc1_set_attenuation(get_channel(TEMP_5_PIN), ADC_ATTEN_11db);
   #endif
   #if HAS_HEATED_BED
-    adc1_config_channel_atten(get_channel(TEMP_BED_PIN), ADC_ATTEN_11db);
+    adc1_set_attenuation(get_channel(TEMP_BED_PIN), ADC_ATTEN_11db);
   #endif
   #if HAS_TEMP_CHAMBER
-    adc1_config_channel_atten(get_channel(TEMP_CHAMBER_PIN), ADC_ATTEN_11db);
+    adc1_set_attenuation(get_channel(TEMP_CHAMBER_PIN), ADC_ATTEN_11db);
   #endif
   #if ENABLED(FILAMENT_WIDTH_SENSOR)
-    adc1_config_channel_atten(get_channel(FILWIDTH_PIN), ADC_ATTEN_11db);
+    adc1_set_attenuation(get_channel(FILWIDTH_PIN), ADC_ATTEN_11db);
   #endif
 
   // Note that adc2 is shared with the WiFi module, which has higher priority, so the conversion may fail.
   // That's why we're not setting it up here.
 
-  // Calculate ADC characteristics i.e. gain and offset factors
-  esp_adc_cal_characterize(ADC_UNIT_1, ADC_ATTEN_DB_11, ADC_WIDTH_BIT_12, V_REF, &characteristics);
+  // Calculate ADC characteristics (i.e., gain and offset factors for each attenuation level)
+  for (int i = 0; i < ADC_ATTEN_MAX; i++) {
+    esp_adc_cal_characterize(ADC_UNIT_1, (adc_atten_t)i, ADC_WIDTH_BIT_12, V_REF, &characteristics[i]);
+    
+    // Change attenuation 100mV below the calibrated threshold
+    thresholds[i] = esp_adc_cal_raw_to_voltage(4095, &characteristics[i]);
+  }
 }
 
 void HAL_adc_start_conversion(uint8_t adc_pin) {
+  const adc1_channel_t chan = get_channel(adc_pin);
   uint32_t mv;
-  esp_adc_cal_get_voltage((adc_channel_t)get_channel(adc_pin), &characteristics, &mv);
+  esp_adc_cal_get_voltage((adc_channel_t)chan, &characteristics[attenuations[chan]], &mv);
+
+  // Change the attenuation level based on the new reading
+  adc_atten_t atten;
+  if (mv < thresholds[ADC_ATTEN_DB_0] - 100)
+    adc1_set_attenuation(chan, ADC_ATTEN_DB_0);
+  else if (mv > thresholds[ADC_ATTEN_DB_0] - 50 && mv < thresholds[ADC_ATTEN_DB_2_5] - 100)
+    adc1_set_attenuation(chan, ADC_ATTEN_DB_2_5);
+  else if (mv > thresholds[ADC_ATTEN_DB_2_5] - 50 && mv < thresholds[ADC_ATTEN_DB_6] - 100)
+    adc1_set_attenuation(chan, ADC_ATTEN_DB_6);
+  else if (mv > thresholds[ADC_ATTEN_DB_6] - 50)
+    adc1_set_attenuation(chan, ADC_ATTEN_DB_11);
+
   HAL_adc_result = mv * 1023.0 / 3300.0;
 }