Added driver EncoderInput

Author: TomSaw

src/modm/driver/encoder/encoder_input.hpp

@@ -0,0 +1,70 @@
+/*
+ * Copyright (c) 2021, Thomas Sommer
+ *
+ * This file is part of the modm project.
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/.
+ */
+
+#pragma once
+
+#include <modm/platform.hpp>
+
+namespace modm
+{
+/**
+ * @brief 			Gray code decoder using STM32 Timer mode
+ *
+ * @tparam Timer 	STM32 General purpose timer
+ * @tparam SignalA	First modm::platform::Gpio pin that connects to Timer::Ch1
+ * @tparam SignalB	Second modm::platform::Gpio pin that connects to Timer::Ch2
+ */
+template<class Timer, typename SignalA, typename SignalB, uint16_t POSTSCALER = 4, std::signed_integral ValueType = int8_t>
+class EncoderInput
+{
+public:
+	void
+	initialize(const bool invert = false, const uint8_t filter = 4)
+	{
+		// TODO Pullup optional?
+		SignalA::setInput(modm::platform::Gpio::InputType::PullUp);
+		SignalB::setInput(modm::platform::Gpio::InputType::PullUp);
+		Timer::template connect<typename SignalA::Ch1, typename SignalB::Ch2>();
+
+		Timer::enable();
+
+		Timer::setMode(invert ? Timer::Mode::UpCounter : Timer::Mode::DownCounter, Timer::SlaveMode::Encoder3);
+		Timer::setPrescaler(POSTSCALER);
+
+		if(filter) {
+			Timer::configureInputChannel(1, filter);
+			Timer::configureInputChannel(2, filter);
+		}
+
+		Timer::applyAndReset();
+		Timer::start();
+		last = Timer::getValue();
+	}
+
+	uint16_t
+	getValue()
+	{
+		return Timer::getValue();
+	}
+
+	ValueType
+	getIncrement()
+	{
+		uint16_t current = Timer::getValue();
+		int16_t delta = current - last;
+		last = current;
+		return delta;
+	}
+
+
+private:
+	uint16_t last = 0;
+};
+}  // namespace modm

src/modm/driver/encoder/encoder_input.lb

@@ -0,0 +1,28 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+#
+# Copyright (c) 2021, Thomas Sommer
+#
+# This file is part of the modm project.
+#
+# This Source Code Form is subject to the terms of the Mozilla Public
+# License, v. 2.0. If a copy of the MPL was not distributed with this
+# file, You can obtain one at http://mozilla.org/MPL/2.0/.
+# -----------------------------------------------------------------------------
+
+def init(module):
+    module.name = ":driver:encoder_input"
+    module.description = """
+# Quadrature Encoder Input using STM32 general purpose Timer
+
+This driver decodes a AB (incremental) encoder signal.
+"""
+
+def prepare(module, options):
+	# TODO requires STM32 architecture
+    module.depends(":architecture:atomic")
+    return True
+
+def build(env):
+    env.outbasepath = "modm/src/modm/driver/encoder"
+    env.copy("encoder_input.hpp")