Implement DAC for enabled boards

Fixes #9

Author: facchinm

cores/arduino/wiring_analog.cpp

@@ -27,6 +27,21 @@
 static int write_resolution = 8;
 static int read_resolution = 10;
 
+#if DEVICE_ANALOGOUT
+#include "mbed/drivers/AnalogOut.h"
+mbed::AnalogOut* dac = NULL;
+void analogWriteDAC(PinName pin, int val) {
+  if (dac == NULL) {
+    dac = new mbed::AnalogOut(pin);
+  }
+  float percent = (float)val/(float)(1 << write_resolution);
+  if (percent > 1.0f) {
+    percent = 1.0f;
+  }
+  dac->write(percent);
+}
+#endif
+
 void analogWrite(PinName pin, int val)
 {
   pin_size_t idx = PinNameToIndex(pin);
@@ -45,6 +60,12 @@ void analogWrite(pin_size_t pin, int val)
   if (pin >= PINS_COUNT) {
     return;
   }
+#ifdef DAC
+    if (pin == DAC) {
+      analogWriteDAC(digitalPinToPinName(pin), val);
+      return;
+    }
+#endif
   float percent = (float)val/(float)(1 << write_resolution);
   mbed::PwmOut* pwm = digitalPinToPwm(pin);
   if (pwm == NULL) {

variants/PORTENTA_H7_M4/pins_arduino.h

@@ -39,6 +39,9 @@ static const uint8_t A5  = PIN_A5;
 static const uint8_t A6  = PIN_A6;
 #define ADC_RESOLUTION 12
 
+//DACs
+#define DAC           (A6)
+
 // Serial
 #define PIN_SERIAL_RX (13ul)
 #define PIN_SERIAL_TX (14ul)
@@ -97,6 +100,6 @@ void _ontouch1200bps_();
 #define SPI_MOSI			(digitalPinToPinName(PIN_SPI_MOSI))
 #define SPI_SCK				(digitalPinToPinName(PIN_SPI_SCK))
 
-#define digitalPinToPort(P)		(digitalPinToPinName(P)/32)
+#define digitalPinToPort(P)		(digitalPinToPinName(P)/16)
 
 #endif //__PINS_ARDUINO__

variants/PORTENTA_H7_M7/pins_arduino.h

@@ -39,6 +39,9 @@ static const uint8_t A5  = PIN_A5;
 static const uint8_t A6  = PIN_A6;
 #define ADC_RESOLUTION 12
 
+//DACs
+#define DAC           (A6)
+
 // Serial
 #define PIN_SERIAL_RX (13ul)
 #define PIN_SERIAL_TX (14ul)
@@ -91,7 +94,6 @@ void _ontouch1200bps_();
 #define I2C_SDA1			I2C_SDA_INTERNAL
 #define I2C_SCL1			I2C_SCL_INTERNAL
 
-
 #define SPI_HOWMANY			1
 
 #define SPI_MISO			(digitalPinToPinName(PIN_SPI_MISO))