analogWrite: implement DAC pins

Author: facchinm

cores/arduino/Arduino.h

@@ -13,6 +13,7 @@
 #include <zephyr/drivers/gpio.h>
 #include <zephyr/drivers/pwm.h>
 #include <zephyr/drivers/adc.h>
+#include <zephyr/drivers/dac.h>
 #include <zephyr/drivers/i2c.h>
 #include <math.h>
 
@@ -52,6 +53,17 @@ enum analogPins {
 };
 #endif
 
+#ifdef CONFIG_DAC
+
+#undef DAC0
+#undef DAC1
+#undef DAC2
+#undef DAC3
+#define DAC_ENUMS(n, p, i) DAC ## i = i,
+enum dacPins { DT_FOREACH_PROP_ELEM(DT_PATH(zephyr_user), dac_channels, DAC_ENUMS) NUM_OF_DACS };
+
+#endif
+
 void interrupts(void);
 void noInterrupts(void);
 
@@ -62,6 +74,9 @@ int digitalPinToInterrupt(pin_size_t pin);
 #define portOutputRegister(x) (x)
 #define portInputRegister(x) (x)
 
+void analogReadResolution(int bits);
+void analogWriteResolution(int bits);
+
 #include <variant.h>
 #ifdef __cplusplus
 #include <SerialUSB.h>
@@ -70,6 +85,7 @@ int digitalPinToInterrupt(pin_size_t pin);
 #include <strings.h>
 #include <api/itoa.h>
 #include <time_macros.h>
+#include <overloads.h>
 
 // Allow namespace-less operations if Arduino.h is included
 using namespace arduino;

cores/arduino/overloads.h

@@ -0,0 +1,9 @@
+#ifdef CONFIG_DAC
+
+void analogWrite(enum dacPins pinNumber, int value);
+
+#endif
+
+// In c++ mode, we also provide analogReadResolution and analogWriteResolution getters
+int analogReadResolution();
+int analogWriteResolution();

cores/arduino/zephyrCommon.cpp

@@ -187,6 +187,28 @@ size_t analog_pin_index(pin_size_t pinNumber) {
 
 #endif //CONFIG_ADC
 
+#ifdef CONFIG_DAC
+
+#if (DT_NODE_HAS_PROP(DT_PATH(zephyr_user), dac))
+
+#define DAC_NODE DT_PHANDLE(DT_PATH(zephyr_user), dac)
+#define DAC_RESOLUTION DT_PROP(DT_PATH(zephyr_user), dac_resolution)
+static const struct device *const dac_dev = DEVICE_DT_GET(DAC_NODE);
+
+#define DAC_CHANNEL_DEFINE(n, p, i) \
+  { \
+    .channel_id = DT_PROP_BY_IDX(n, p, i), \
+    .resolution = DAC_RESOLUTION, \
+    .buffered = true, \
+  },
+
+static const struct dac_channel_cfg dac_ch_cfg[] =
+  { DT_FOREACH_PROP_ELEM(DT_PATH(zephyr_user), dac_channels, DAC_CHANNEL_DEFINE) };
+
+#endif
+
+#endif //CONFIG_DAC
+
 static unsigned int irq_key;
 static bool interrupts_disabled = false;
 }  // namespace
@@ -297,6 +319,16 @@ unsigned long millis(void) {
   return k_uptime_get_32();
 }
 
+#if defined(CONFIG_DAC) || defined(CONFIG_PWM)
+static int _analog_write_resolution = 8;
+void analogWriteResolution(int bits) {
+    _analog_write_resolution = bits;
+}
+int analogWriteResolution() {
+  return _analog_write_resolution;
+}
+#endif
+
 #ifdef CONFIG_PWM
 
 void analogWrite(pin_size_t pinNumber, int value)
@@ -311,6 +343,8 @@ void analogWrite(pin_size_t pinNumber, int value)
     return;
   }
 
+  value = map(value, 0, 1 << _analog_write_resolution, 0, arduino_pwm[idx].period);
+
   if (((uint32_t)value) > arduino_pwm[idx].period) {
     value = arduino_pwm[idx].period;
   } else if (value < 0) {
@@ -326,6 +360,21 @@ void analogWrite(pin_size_t pinNumber, int value)
 
 #endif
 
+#ifdef CONFIG_DAC
+void analogWrite(enum dacPins dacName, int value)
+{
+  if (dacName >= NUM_OF_DACS) {
+    return;
+  }
+
+  dac_channel_setup(dac_dev, &dac_ch_cfg[dacName]);
+
+  const int max_dac_value = 1U << dac_ch_cfg[dacName].resolution;
+  dac_write_value(dac_dev, dac_ch_cfg[dacName].channel_id, map(value, 0, 1 << _analog_write_resolution, 0, max_dac_value));
+}
+#endif
+
+
 #ifdef CONFIG_ADC
 
 void analogReference(uint8_t mode)