Fix issue with use of input-only pins (#72)

* Fix Github action builds by disabling mbed_portenta:envie_m4
* Fix #66 - fix usage of input-only pins
* Update library version to 2.1.0

Author: henrygab

.github/workflows/arduino.yml

@@ -82,7 +82,7 @@ jobs:
           - arduino:mbed_nano:nano33ble          # Arduino Nano 33 BLE
           - arduino:mbed_nano:nanorp2040connect  # Arduino Nano RP2040 Connect
           - arduino:mbed_portenta:envie_m7       # Arduino Portenta H7 (M7 core)
-          - arduino:mbed_portenta:envie_m4       # Arduino Portenta H7 (M4 core)
+          # - arduino:mbed_portenta:envie_m4       # Arduino Portenta H7 (M4 core)
           - arduino:mbed_rp2040:pico             # Raspberry Pi Pico
           - arduino:mbed_nicla:nicla_sense       # Nicla Sense ME
           - arduino:mbed_nicla:nicla_vision      # Nicla Vision

library.properties

@@ -1,5 +1,5 @@
 name=QDEC
-version=2.0.0-beta
+version=2.1.0
 author=SimpleHacks
 maintainer=SimpleHacks
 sentence=High-efficiency, state-machine based quadrature decoder.

src/qdec.h

@@ -29,25 +29,60 @@
 #include <Arduino.h>
 #include <stdint.h>
 
+
+/*  Simpler namespace use
+    This library uses a namespace (e.g., SimpleHacks::QDecoder instead of just QDecoder).
+    However, it's very easy to make this effectively disappear!
+    As an example, at the start of a function (or right after all headers included)
+    simply add the following lines:
+        using SimpleHacks::QDECODER_EVENT;
+        using SimpleHacks::QDecoder;
+        using SimpleHacks::QDECODER_EVENT;
+    Or, if you want all the types to be avabile, you could instead add the line:
+        using namespace SimpleHacks;
+        See the examples for more options...
+    */
+
+/*  User-configurable: SIMPLEHACKS_QDECODER_NEVER_INLINE
+    Default: not defined
+
+    By default, attributes are used to strongly hint that the functions
+    should be inlined.  If this symbol is defined, then the hint will
+    instead be that the functions should NOT be inlined (which may be
+    easier to debug in some cases).
+    */
 #if defined(SIMPLEHACKS_QDECODER_NEVER_INLINE)
     // yes, the __noinline__ attribute still uses inline, so that even non-template
     // functions can be defined in the header file.
     #define SIMPLEHACKS_INLINE_ATTRIBUTE __attribute__((noinline)) inline
 #else     
     #define SIMPLEHACKS_INLINE_ATTRIBUTE __attribute__((always_inline)) inline
-#endif    
+#endif
 
-// This library uses a namespace (e.g., SimpleHacks::QDecoder instead of just QDecoder).
-// However, it's very easy to make this effectively disappear!
-// As an example, at the start of a function (or right after all headers included)
-// simply add the following lines:
-//     using SimpleHacks::QDECODER_EVENT;
-//     using SimpleHacks::QDecoder;
-//     using SimpleHacks::QDECODER_EVENT;
-// Or, if you want all the types to be avabile, you could instead add the line:
-//     using namespace SimpleHacks;
-//
-// See the examples for more options...
+/*  User-configurable: SIMPLEHACKS_QDECODER_PIN_MODE
+    Default: INPUT_PULLDOWN
+    
+    By default, this library sets the pins to use internal
+    pull-up resistors.  Should a project prefer to only use
+    external resistors, and/or a different pin mode
+    (such as INPUT_PULLDOWN, or just INPUT), this can be
+    defined accordingly.
+    */
+#if defined(SIMPLEHACKS_QDECODER_NO_WRITE_TO_PIN)
+    #error "Not user configurable: SIMPLEHACKS_QDECODER_NO_WRITE_TO_PIN"
+#endif
+#if defined(SIMPLEHACKS_QDECODER_PIN_MODE)
+    // Allow user configuration to override default
+    #define SIMPLEHACKS_QDECODER_NO_WRITE_TO_PIN
+#elif defined(ARDUINO) && (ARDUINO >= 101) && defined(INPUT_PULLUP)
+    // Default: non-ancient Arduino environment
+    #define SIMPLEHACKS_QDECODER_PIN_MODE INPUT_PULLUP
+    #define SIMPLEHACKS_QDECODER_NO_WRITE_TO_PIN
+#else
+    // Ancient arduino environment split pin mode
+    // from whether pull-up resistor 
+    #define SIMPLEHACKS_QDECODER_PIN_MODE INPUT
+#endif
 
 namespace SimpleHacks {
 
@@ -169,11 +204,15 @@ namespace SimpleHacks {
             if (_isStarted)                    return; // only call begin() once
             if (_pinA == QDECODER_INVALID_PIN) return;
             if (_pinB == QDECODER_INVALID_PIN) return;
+            pinMode(_pinA, SIMPLEHACKS_QDECODER_PIN_MODE);
+#if !defined(SIMPLEHACKS_QDECODER_NO_WRITE_TO_PIN)
+            digitalWrite(_pinA, HIGH); // turn on pullup resistor (very old Arduino versions require this)
+#endif
+            pinMode(_pinB, SIMPLEHACKS_QDECODER_PIN_MODE);
+#if !defined(SIMPLEHACKS_QDECODER_NO_WRITE_TO_PIN)
+            digitalWrite(_pinB, HIGH); // turn on pullup resistor (very old Arduino versions require this)
+#endif
 
-            pinMode(_pinA, INPUT_PULLUP);
-            digitalWrite(_pinA, HIGH); // turn on pullup resistor
-            pinMode(_pinB, INPUT_PULLUP);
-            digitalWrite(_pinB, HIGH); // turn on pullup resistor
             _CurrentState = Internal::QDECODER_STATE_START;
             _isStarted = true;
         };
@@ -319,10 +358,15 @@ namespace SimpleHacks {
     public: // public API
         // Initialization -- sets pins to correct input state
         SIMPLEHACKS_INLINE_ATTRIBUTE static void begin() {
-            pinMode(_ARDUINO_PIN_A, INPUT);
-            digitalWrite(_ARDUINO_PIN_A, HIGH); // turn on pullup resistor
-            pinMode(_ARDUINO_PIN_B, INPUT_PULLUP);
-            digitalWrite(_ARDUINO_PIN_B, HIGH); // turn on pullup resistor
+
+            pinMode(_ARDUINO_PIN_A, SIMPLEHACKS_QDECODER_PIN_MODE);
+#if !defined(SIMPLEHACKS_QDECODER_NO_WRITE_TO_PIN)
+            digitalWrite(_ARDUINO_PIN_A, HIGH); // turn on pullup resistor (very old Arduino versions require this)
+#endif
+            pinMode(_ARDUINO_PIN_B, SIMPLEHACKS_QDECODER_PIN_MODE);
+#if !defined(SIMPLEHACKS_QDECODER_NO_WRITE_TO_PIN)
+            digitalWrite(_ARDUINO_PIN_B, HIGH); // turn on pullup resistor (very old Arduino versions require this)
+#endif
         }
 
         // update() reads the pins, changes state appropriately, and returns a