Add analogRead and A0...A3 pins

cores/rp2040/Arduino.h

@@ -29,13 +29,21 @@ typedef uint8_t pin_size_t;
 
 
 void pinMode(pin_size_t pinNumber, PinMode pinMode);
+
+// SIO (GPIO)
 void digitalWrite(pin_size_t pinNumber, PinStatus status);
 PinStatus digitalRead(pin_size_t pinNumber);
 
+// ADC
+static const pin_size_t A0 = 26;
+static const pin_size_t A1 = 27;
+static const pin_size_t A2 = 28;
+static const pin_size_t A3 = 29;
+int analogRead(pin_size_t pinNumber);
 
+// PWM
 void analogWrite(pin_size_t pinNumber, int value);
 
-
 void delay(unsigned long);
 void delayMicroseconds(unsigned int us);
 unsigned long millis();

cores/rp2040/wiring_analog.cpp

@@ -20,6 +20,7 @@
 #include "../../pico-sdk/src/rp2_common/hardware_clocks/include/hardware/clocks.h"
 #include "../../pico-sdk/src/rp2_common/hardware_pll/include/hardware/pll.h"
 #include "../../pico-sdk/src/rp2_common/hardware_clocks/include/hardware/clocks.h"
+#include "../../pico-sdk/src/rp2_common/hardware_adc/include/hardware/adc.h"
 
 static int32_t analogScale = 255;
 static uint32_t analogMap = 0;
@@ -77,3 +78,16 @@ extern "C" void analogWrite(pin_size_t pin, int val) {
   pwm_set_gpio_level(pin, val);
 }
 
+extern "C" int analogRead(pin_size_t pinNumber) {
+  if ((pinNumber < A0) || (pinNumber > A3)) {
+    return 0;
+  }
+  static bool adcInitted = false;
+  if (!adcInitted) {
+    adc_init();
+  }
+  adc_gpio_init(pinNumber);
+  adc_select_input(pinNumber - A0);
+  return adc_read();
+}
+