improved modm:driver:encoder_input.bitbang

Author: TomSaw

src/modm/driver/encoder/bitbang_encoder_input.hpp

@@ -26,18 +26,19 @@ namespace modm
  *
  * @tparam SignalA          First modm::platform::Gpio pin to input the encoder signal.
  * @tparam SignalB          Second modm::platform::Gpio pin to input the encoder signal.
- * @tparam POSTSCALER	 	n_cycles to count as one in-/decrement.
- * @tparam DeltaType		Must be signed integer and fit at least POSTSCALER. The Bigger
+ * @tparam PRESCALER	 	n_cycles to count as one in-/decrement.
+ * @tparam DeltaType		Must be signed integral and fit at least PRESCALER. The Bigger
  * 							DeltaType, the more inc-/decrements can be stored temporarily.
+ * @tparam ValueType		Must be unsigned integral.
  */
-template<typename SignalA, typename SignalB, uint8_t POSTSCALER = 4,
+template<typename SignalA, typename SignalB, uint8_t PRESCALER = 4,
 		 std::signed_integral DeltaType = int8_t>
 class BitBangEncoderInput
 {
-	static_assert(std::popcount(POSTSCALER) == 1,
-				  "POSTSCALER must be an integer to basis 2 and not 0: 1, 2, 4, 8, 16, ...");
-	static_assert(POSTSCALER <= std::numeric_limits<DeltaType>::max(),
-				  "DeltaType is to small for POSTSCALER.");
+	static_assert(std::popcount(PRESCALER) == 1,
+				  "PRESCALER must be an integer to basis 2 and not 0: 1, 2, 4, 8, 16, ...");
+	static_assert(PRESCALER <= std::numeric_limits<DeltaType>::max(),
+				  "DeltaType is to small for PRESCALER.");
 
 	using Signals = modm::platform::SoftwareGpioPort<SignalA, SignalB>;
 
@@ -47,19 +48,19 @@ class BitBangEncoderInput
 	uint8_t inline getRaw();
 
 public:
-	using ValueType = DeltaType;
 	BitBangEncoderInput() : raw_last(0), delta(0){};
 
+	using InputType = modm::platform::Gpio::InputType;
 	// Connect SingalA and SignalB and store power-up state
 	inline void
-	connect();
+	initialize(const modm::platform::Gpio::InputType inputType = modm::platform::Gpio::InputType::PullUp);
 
 	// Call @1kHz for manual movement
 	inline void
 	update();
 
-	ValueType
-	getIncrement();
+	DeltaType
+	getDelta();
 
 private:
 	uint8_t raw_last;

src/modm/driver/encoder/bitbang_encoder_input.lb

@@ -15,7 +15,7 @@ def init(module):
     module.description = """
 # Quadrature Encoder Input
 
-This driver decodes a AB (incremental) encoder signal.
+This driver decodes an AB (incremental) encoder signal.
 Ported from code created by Peter Dannegger:
 https://www.mikrocontroller.net/articles/Drehgeber.
 """

src/modm/driver/encoder/bitbang_encoder_input_impl.hpp

@@ -15,10 +15,9 @@
 
 #include <cmath>
 
-template<typename SignalA, typename SignalB, uint8_t POSTSCALER,
-		 std::signed_integral DeltaType>
+template<typename SignalA, typename SignalB, uint8_t PRESCALER, std::signed_integral DeltaType>
 inline uint8_t
-modm::BitBangEncoderInput<SignalA, SignalB, POSTSCALER, DeltaType>::getRaw()
+modm::BitBangEncoderInput<SignalA, SignalB, PRESCALER, DeltaType>::getRaw()
 {
 	const uint8_t read = Signals::read();
 	// convert graycode to binary
@@ -28,42 +27,40 @@ modm::BitBangEncoderInput<SignalA, SignalB, POSTSCALER, DeltaType>::getRaw()
 	return raw;
 }
 
-template<typename SignalA, typename SignalB, uint8_t POSTSCALER,
-		 std::signed_integral DeltaType>
+template<typename SignalA, typename SignalB, uint8_t PRESCALER, std::signed_integral DeltaType>
 inline void
-modm::BitBangEncoderInput<SignalA, SignalB, POSTSCALER, DeltaType>::connect()
+modm::BitBangEncoderInput<SignalA, SignalB, PRESCALER, DeltaType>::initialize(
+	const modm::platform::Gpio::InputType inputType
+)
 {
-	Signals::setInput(::Gpio::InputType::PullUp);
+	Signals::setInput(inputType);
 
 	// Tare power-on state
 	modm::delay(10us);
 	raw_last = getRaw();
 }
 
-template<typename SignalA, typename SignalB, uint8_t POSTSCALER,
-		 std::signed_integral DeltaType>
+template<typename SignalA, typename SignalB, uint8_t PRESCALER, std::signed_integral DeltaType>
 inline void
-modm::BitBangEncoderInput<SignalA, SignalB, POSTSCALER, DeltaType>::update()
+modm::BitBangEncoderInput<SignalA, SignalB, PRESCALER, DeltaType>::update()
 {
-	uint8_t raw = getRaw();
+	const uint8_t raw = getRaw();
 	const uint8_t diff = raw_last - raw;
+
 	if (diff & 0b01)
 	{
 		raw_last = raw;
 		delta += (diff & 0b10) - 1;  // bit 1 = direction (+/-)
 	}
 }
 
-template<typename SignalA, typename SignalB, uint8_t POSTSCALER,
-		 std::signed_integral DeltaType>
+template<typename SignalA, typename SignalB, uint8_t PRESCALER, std::signed_integral DeltaType>
 DeltaType
-modm::BitBangEncoderInput<SignalA, SignalB, POSTSCALER, DeltaType>::getIncrement()
+modm::BitBangEncoderInput<SignalA, SignalB, PRESCALER, DeltaType>::getDelta()
 {
 	::modm::atomic::Lock _;
-	DeltaType val = delta;
-
-	delta &= (POSTSCALER - 1);  // mask out higher bits
 
-	constexpr uint8_t shift = std::log2(POSTSCALER);  // Number of fraction bits
-	return val >> shift;                              // return whats left without fractions
+	DeltaType ret = delta;
+	delta &= (PRESCALER - 1);					// Only keep prescaler fraction
+	return ret >> int(std::log2(PRESCALER));	// return delta without prescaler fraction
 }