Add pi pico support (Arduino-IRremote#955)

* Documentation

* Add support for Pi Pico and other RP2040 boards (non-mbed core)

Only receive was tested.

Co-authored-by: Armin <[email protected]>
Co-authored-by: Thomas Friedrichsmeier <[email protected]>

Author: tfry-git

README.md

@@ -382,6 +382,7 @@ ATtiny and Digispark boards are only tested with the recommended [ATTinyCore](ht
 - Sparkfun Pro Micro
 - Nano Every, Uno WiFi Rev2, nRF5 BBC MicroBit, Nano33_BLE
 - BluePill with STM32
+- RP2040 based boards (Raspberry Pi Pico, etc.)
 
 We are open to suggestions for adding support to new boards, however we highly recommend you contact your supplier first and ask them to provide support from their side.<br/>
 If you can provide **examples of using a periodic timer for interrupts** for the new board, and the board name for selection in the Arduino IDE, then you have way better chances to get your board supported by IRremote.
@@ -458,6 +459,7 @@ The timer and the pin usage can be adjusted in [private/IRTimer.hpp](https://git
 | [Teensy 4.0 - 4.1](https://www.pjrc.com/teensy/pinout.html)              | **FlexPWM1.3**    | **8**               | 7, 25 |
 | [BluePill / STM32F103C8T6](https://github.com/rogerclarkmelbourne/Arduino_STM32)  | **3**    | %                   | **PA6 & PA7 & PB0 & PB1** |
 | [BluePill / STM32F103C8T6](https://stm32-base.org/boards/STM32F103C8T6-Blue-Pill) | **TIM4** | %                   | **PB6 & PB7 & PB8 & PB9** |
+| [RP2040 / Pi Pico](https://github.com/earlephilhower/arduino-pico)       | [default alarm pool](https://raspberrypi.github.io/pico-sdk-doxygen/group__repeating__timer.html) | %                   |  |
 
 ### Why do we use 33% duty cycle for sending
 We do it according to the statement in the [Vishay datasheet](https://www.vishay.com/docs/80069/circuit.pdf):

library.properties

@@ -6,5 +6,5 @@ sentence=Send and receive infrared signals with multiple protocols
 paragraph=Currently included protocols: Denon / Sharp, JVC, LG / LG2,  NEC / Onkyo / Apple, Panasonic / Kaseikyo, RC5, RC6, Samsung, Sony, (Pronto), BoseWave, Lego, Whynter, MagiQuest.<br/><br/><b>New: </b><a href="https://github.com/Arduino-IRremote/Arduino-IRremote#converting-your-program-to-the-31-version">3.x upgrade instructions</a><br/>Added LG2 protocol.<br/>For all 3.x: Generation of PWM is now done by software by default, thus saving the hardware timer and enabling abitrary output pins. Removed decode_results results. Renamed most irparams_struct values. Support for more CPU's.<br/><b>New: </b>Improved support for Teensy boards by Paul Stoffregen.<br/><a href="https://github.com/Arduino-IRremote/Arduino-IRremote/blob/master/changelog.md">Release notes</a><br/>
 category=Communication
 url=https://github.com/Arduino-IRremote/Arduino-IRremote
-architectures=avr,megaavr,samd,esp8266,esp32,stm32,STM32F1,mbed,mbed_nano
+architectures=avr,megaavr,samd,esp8266,esp32,stm32,STM32F1,mbed,mbed_nano,rp2040
 includes=IRremote.hpp

src/private/IRTimer.hpp

@@ -1149,6 +1149,34 @@ void timerConfigForReceive() {
     sMbedTimer.attach(IRTimerInterruptHandler, std::chrono::microseconds(MICROS_PER_TICK));
 }
 
+/***************************************
+ * RP2040 based boards
+ ***************************************/
+#elif defined(ARDUINO_ARCH_RP2040) // Raspberry Pi Pico, Adafruit Feather RP2040, etc.
+#include "pico/time.h"
+#  if defined(SEND_PWM_BY_TIMER)
+#error PWM generation by hardware not implemented for RP2040
+#  endif
+
+#define TIMER_RESET_INTR_PENDING
+#define TIMER_ENABLE_RECEIVE_INTR  add_repeating_timer_us(MICROS_PER_TICK, IRTimerInterruptHandlerHelper, NULL, &sRP2040Timer);
+#define TIMER_DISABLE_RECEIVE_INTR  cancel_repeating_timer(&sRP2040Timer);
+
+// Redefinition of ISR macro which creates a plain function now
+#  ifdef ISR
+#undef ISR
+#  endif
+#define ISR() void IRTimerInterruptHandler(void)
+void IRTimerInterruptHandler();
+bool IRTimerInterruptHandlerHelper(repeating_timer_t *) {
+    IRTimerInterruptHandler();
+    return true;
+}
+
+repeating_timer_t sRP2040Timer;
+
+void timerConfigForReceive() {}
+
 /***************************************
  * NRF5 boards like the BBC:Micro
  ***************************************/