analog: provide analogReference() getter w/ measure

Author: facchinm

cores/arduino/Arduino.h

@@ -86,6 +86,21 @@ pin_size_t digitalPinToInterrupt(pin_size_t pin);
 #define clockCyclesToMicroseconds(a) ( (a) / clockCyclesPerMicrosecond() )
 #define microsecondsToClockCycles(a) ( (a) * clockCyclesPerMicrosecond() )
 
+// analog extra functionalities
+
+typedef enum _ar_aref {
+  AR_INTERNAL,
+  AR_INTERNAL_1_5V,
+  AR_INTERNAL_2_0V,
+  AR_INTERNAL_2_5V,
+  AR_EXTERNAL,
+  AR_DEFAULT,
+} ar_aref;
+
+#if defined(__cplusplus)
+float analogReference();
+#endif
+
 #ifndef NO_USB
 #define Serial  SerialUSB
 #define Serial1 _UART1_

cores/arduino/analog.cpp

@@ -526,24 +526,63 @@ int analogRead(pin_size_t pinNumber) {
   return adcConvert(_adc,cfg_adc);
 }
 
+void analogReference(uint8_t mode) {
 
+ adc_vref_control_t ctrl;
+
+  switch (mode) {
+      case AR_INTERNAL:
+        ctrl = ADC_VREF_CONTROL_IVREF_AVSS0; break;
+      case AR_INTERNAL_1_5V:
+        ctrl = ADC_VREF_CONTROL_1_5V_OUTPUT; break;
+      case AR_INTERNAL_2_0V:
+        ctrl = ADC_VREF_CONTROL_2_0V_OUTPUT; break;
+      case AR_INTERNAL_2_5V:
+        ctrl = ADC_VREF_CONTROL_2_5V_OUTPUT; break;
+      case AR_EXTERNAL:
+        ctrl = ADC_VREF_CONTROL_VREFH0_AVSS0; break;
+      default:
+        ctrl = ADC_VREF_CONTROL_AVCC0_AVSS0; break;
+  }
 
-void analogReference(uint8_t mode) {
-  // TODO: in case VREFH is selected, please configure the pin accordingly
-  // something like
-  // pinPeripheral(digitalPinToBspPin(VREFH), (uint32_t) IOPORT_CFG_PERIPHERAL_PIN | VREFH)
   R_ADC_Close(&adc.ctrl);
-  adc.cfg_extend.adc_vref_control = (adc_vref_control_t)mode;
+  adc.cfg_extend.adc_vref_control = ctrl;
   R_ADC_Open(&adc.ctrl, &adc.cfg);
 
   R_ADC_Close(&adc1.ctrl);
-  adc1.cfg_extend.adc_vref_control = (adc_vref_control_t)mode;
+  adc1.cfg_extend.adc_vref_control = ctrl;
   R_ADC_Open(&adc1.ctrl, &adc1.cfg);
 }
 
-
-
-
+static float aref = 0;
+float analogReference() {
+    switch (adc.cfg_extend.adc_vref_control) {
+      case ADC_VREF_CONTROL_1_5V_OUTPUT:
+        return 1.5;
+      case ADC_VREF_CONTROL_2_0V_OUTPUT:
+        return 2.0;
+      case ADC_VREF_CONTROL_2_5V_OUTPUT:
+        return 2.5;
+      case ADC_VREF_CONTROL_VREFH0_AVSS0:
+        // the user must know the voltage he applies from outside
+        return NAN;
+      default:
+        #if defined(AVCC_MEASURE_PIN)
+        if (aref == 0) {
+          analogReference(AR_INTERNAL);
+          delayMicroseconds(5);
+          for (int i = 0; i < 10; i++) {
+            aref += analogRead(AVCC_MEASURE_PIN) * 1.43f  * AVCC_MULTIPLY_FACTOR / (1 << _analogRequestedReadResolution);
+          }
+          aref = aref / 10;
+          analogReference(AR_DEFAULT);
+        }
+        return aref;
+        #else
+        return NAN;
+        #endif
+    }
+}
 
 void analogReadResolution(int bits) {
   /* 20221109 [maidnl] FIX Requested resolution: 

cores/arduino/main.cpp

@@ -92,6 +92,7 @@ void arduino_main(void)
 
    _init();
    initVariant();
+   analogReference();
 #ifndef NO_USB
    __USBStart();
    Serial.begin(115200);

variants/SANTIAGO/pins_arduino.h

@@ -138,6 +138,9 @@ static const uint8_t SS  =  PIN_SPI_CS;
 
 #define EXT_INTERRUPTS_HOWMANY 2
 
+#define AVCC_MEASURE_PIN        36
+#define AVCC_MULTIPLY_FACTOR    8.33
+
 #define USB_VID           (0x2341)
 #define USB_PID           (0x0069)
 #define USB_NAME          "Santiago"

variants/SANTIAGO/variant.cpp

@@ -120,6 +120,7 @@ extern "C" const PinMuxCfg_t g_pin_cfg[] = {
   { BSP_IO_PORT_04_PIN_08,    P408   }, /* (34) D34  EXT_SCL */
   { BSP_IO_PORT_04_PIN_09,    P409   }, /* (35) D35  EXT_SDA */
 
+  { BSP_IO_PORT_05_PIN_00,    P500   }, /* (36) Analog voltage measure pin  */
 };
 
 extern "C" const size_t g_pin_cfg_size = sizeof(g_pin_cfg);

variants/SANTIAGO_COMPOSTA/pins_arduino.h

@@ -119,7 +119,6 @@ static const uint8_t SS  =  PIN_SPI_CS;
 /****** AGT CORE DEFINES *******/
 #define AGT_HOWMANY       2
 
-
 /****** CAN CORE DEFINES ******/
 
 #define CAN_HOWMANY       1
@@ -130,6 +129,9 @@ static const uint8_t SS  =  PIN_SPI_CS;
 
 #define EXT_INTERRUPTS_HOWMANY 2
 
+#define AVCC_MEASURE_PIN        38
+#define AVCC_MULTIPLY_FACTOR    8.33
+
 #define USB_VID           (0x2341)
 #define USB_PID           (0x0069)
 #define USB_NAME          "Santiago"

variants/SANTIAGO_COMPOSTA/variant.cpp

@@ -119,6 +119,8 @@ extern "C" const PinMuxCfg_t g_pin_cfg[] = {
   { BSP_IO_PORT_02_PIN_06,    P206   }, /* (33) D33  */
   { BSP_IO_PORT_02_PIN_13,    P213   }, /* (34) D34  */
   { BSP_IO_PORT_02_PIN_12,    P212   }, /* (35) D35  */
+
+  { BSP_IO_PORT_05_PIN_00,    P500   }, /* (36) Analog voltage measure pin  */
 };
 
 extern "C" const size_t g_pin_cfg_size = sizeof(g_pin_cfg);