Updated code for multi-board compatibility

README.md

@@ -3,7 +3,7 @@ Arduino library for SBUS (Futaba)
 
 SBUS library supports synchronous (blocking) or asynchronous (non-blocking) decoding of Futaba SBUS **without** requiring a **TTL inverter**.
 
-SBUS uses the TIMER 2 and the Pin Change interrupt. It doesn't use UARTs, so those pins can be used:
+SBUS uses the TIMER 0 and the Pin Change interrupt. It doesn't use UARTs, so those pins can be used:
 ```
  Arduino Uno/Nano/Mini: All pins are usable
  Arduino Mega: 10, 11, 12, 13, 50, 51, 52, 53, A8 (62), A9 (63), A10 (64),
@@ -59,6 +59,34 @@ void loop() {
 
 sbus.waitFrame() needs to be called. It returns "false" on timeout (default is 2 seconds). sbus.waitFrame() waits for the next frame the returns.
 
+===== Additional Notes =====
 
+Thank you to fdivitto. Your work is awesome!
+
+Supported Pins
+For unlisted boards, 
+1. Check the interrupt vector table for listing of PCINTx_vect
+2. Chip pinouts for PCINTx, corresponding to PCINTx_vect
+3. TIMER0 is an 8-bit timer
+
+ATMega328P (Uno, Nano): 
+ISRN(0): D8,D9,D10,D11,D12,D13 
+ISRN(1): A0,A1,A2,A3,A4,A5,D0,D1
+ISRN(2): D2,D3,D4,D5,D6,D7
+VERIFIED 8-BIT TIMER ON TC0 and TC2
+
+ATMega32u4 (Leonardo, Micro):
+ISRN(0): SS(PB0),SCK(PB1),MOSI(PB2),MISO(PB3),8,9,10,11
+VERIFIED 8BIT TIMER ON TC0
+
+ATMega2560 (Mega2560): 
+ISRN(0): SS(PB0),SCK(PB1),MOSI(PB2),MISO(PB3),D1,D10,D11,D12,D13
+ISRN(1): D0,D15,D14
+ISRN(2): A8,A9,A10,A11,A12,A13,A14,A15
+VERIFIED 8-BIT TIMER ON TC0
+
+===== CHANGES =====
+Changed TIMER2 to TIMER0 for support for more boards; especially the ATMega32u4
+Conditional ISR for PinChangeInterrupt, since the smaller boards only have PCINT0_vect interrupt vector.
 
 

sbus.cpp

@@ -2,6 +2,7 @@
   sbus.cpp
 
   Copyright (c) 2017, Fabrizio Di Vittorio (fdivitto2013@gmail.com)
+  Edited by ultimate1112.
 
   This library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
@@ -21,7 +22,7 @@
 #include "sbus.h"
 
 
-// quick IO functions
+// Quick IO functions
 #define portOfPin(P)        portOutputRegister(digitalPinToPort(P))
 #define ddrOfPin(P)         portModeRegister(digitalPinToPort(P))
 #define pinOfPin(P)         portInputRegister(digitalPinToPort(P))
@@ -89,42 +90,49 @@ inline void disablePinChangeInterrupts()
 }
 
 
-// handle pin change interrupt here
+// Handle pin change interrupt here
 static void handleInterrupt();
 #define ISRN(N) ISR(PCINT ## N ## _vect) { if (s_PCICRMask == 1 << (N)) handleInterrupt(); }
-ISRN(0) ISRN(1) ISRN(2)
+
+// Define Pin Change Interrupts for specific board
+#if defined(__AVR_ATmega1280__) || defined(__AVR_ATmega2560__) || defined(__AVR_ATmega328P__)
+  ISRN(0) ISRN(1) ISRN(2)
+#else
+  // Fall back to PCINT[0-7]
+  ISRN(0)
+#endif
 
 static void handleInterrupt()
 {
 
   // start bit?
   if (pinGet(s_pin, s_pinMask)) {
 
-    // reset timer 2 counter
-    TCNT2 = 0;
+    // reset timer 0 counter
+    TCNT0 = 0;
 
     disablePinChangeInterrupts();
 
     // start bit received    
     uint8_t receivingWord = 0;    
 
-    // reset OCF2A flag by writing "1"
-    TIFR2 |= 1 << OCF2A;
+    // reset OCF0A flag by writing "1"
+    TIFR0 |= 1 << OCF0A;
 
     uint8_t parity = 0xFF;    
 
     // receive other bits (including parity bit, ignore stop bits)
     for (uint8_t receivedBitIndex = 0; receivedBitIndex < 9; ++receivedBitIndex) {
 
-      // wait for TCNT2 == OCR2A      
+      // wait for TCNT0 == OCR0A      
       // warn: inside this loop interrupts are re-enabled to allow other libraries to work correctly (ie Servo library)
       interrupts();
-      while (!(TIFR2 & (1 << OCF2A)))
+      while (!(TIFR0 & (1 << OCF0A)))
         ;
       noInterrupts();
 
-      // reset OCF2A flag by writing "1"
-      TIFR2 |= 1 << OCF2A;
+      // reset OCF0A flag by writing "1"
+      TIFR0 |= 1 << OCF0A;
 
       // sample current bit  
       if (pinGet(s_pin, s_pinMask))
@@ -272,17 +280,17 @@ void SBUS::begin(uint8_t pin, mode_t mode)
   s_pinMask    = pinMask(pin);
   s_PCICRMask  = 1 << digitalPinToPCICRbit(pin);
 
-  //// setup TIMER 2 CTC
+  //// setup TIMER 0 CTC
 
   // select "Clear Timer on Compare (CTC)" mode
-  TCCR2A = 1 << WGM21; 
+  TCCR0A = 1 << WGM01; 
 
   // no prescaling
-  TCCR2B = 1 << CS20; 
+  TCCR0B = 1 << CS00; 
 
-  // set TOP timer 2 value
+  // set TOP timer 0 value
   // with no-prescaler 1/16000000=0.00000000625, each bit requires 10us, so reset timer 2 every 10us, so reset timer every 10/0.0625 = 160 ticks
-  OCR2A = F_CPU / 1000000 * 10 - 1; // for 16MHz = 159;  
+  OCR0A = F_CPU / 1000000 * 10 - 1; // for 16MHz = 159;  
 
   //// setup pin change interrupt