[driver] Driver for AB (incremental) encoder slave

src/modm/driver/encoder/encoder_slave.hpp

@@ -0,0 +1,77 @@
+// coding: utf-8
+/*
+ * Copyright (c) 2019, Raphael Lehmann
+ *
+ * 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/.
+ */
+// ----------------------------------------------------------------------------
+
+#ifndef MODM_ENCODER_SLAVE_HPP
+#define MODM_ENCODER_SLAVE_HPP
+
+#include <modm/processing/timer/timeout.hpp>
+
+namespace modm
+{
+
+/**
+ * @ingroup modm_driver_encoder_slave
+ * @author  Raphael Lehmann
+ *
+ * @brief               This driver generates a AB (incremental) encoder signal to
+ *                        emulate a hardware encoder with a microcontroller.
+ *
+ * @tparam PinA         First modm::platform::Gpio pin to output the encoder signal.
+ * @tparam PinB         Second modm::platform::Gpio pin to output the encoder signal.
+ * @tparam PositionType Data type (integer) of the position value, default `int32_t`.
+ * @tparam Timeout      Defaults to `modm::ShortTimeout`, must be replaced for
+ *                        encoder frequencies above 1kHz by a class that offers
+ *                        time steps less than 1ms.
+ * @tparam period_ms    Timebase for the output signal. This limits the maximal
+ *                        frequency of the encoder signal. Defaults to `1`.
+ */
+template < class PinA, class PinB, typename PositionType = int32_t, class Timeout = modm::ShortTimeout, uint32_t period_ms = 1 >
+class EncoderSlave {
+public:
+	/**
+	 * @brief Initializes the Encoder.
+	 *
+	 * Sets pins (PinA and PinB) as output pins.
+	 */
+	EncoderSlave();
+
+	/**
+	 * @brief Update method. Generates the encoder signal.
+	 *
+	 * Call this function in your main loop.
+	 */
+	void update();
+
+	/**
+	 * @brief Set the position for the encoder.
+	 * @param position The position setpoint for the encoder.
+	 */
+	void setPosition(PositionType position) { setpoint = position; };
+
+private:
+	PositionType setpoint;
+	PositionType actualValue;
+	Timeout timeout;
+	enum class State : uint8_t {
+		State0,
+		State1,
+		State2,
+		State3,
+	};
+	State state;
+};
+
+}
+
+#include "encoder_slave_impl.hpp"
+
+#endif

src/modm/driver/encoder/encoder_slave.lb

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+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+#
+# Copyright (c) 2019, Raphael Lehmann
+#
+# 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.parent = "driver"
+    module.name = "encoder.slave"
+    module.description = """\
+# Encoder Slave
+
+This driver generates a AB (incremental) encoder signal to
+emulate a hardware encoder with a microcontroller.
+"""
+
+def prepare(module, options):
+    module.depends(
+        ":architecture:gpio",
+        ":processing:timer")
+    return True
+
+def build(env):
+    env.outbasepath = "modm/src/modm/driver/encoder"
+    env.copy("encoder_slave.hpp")
+    env.copy("encoder_slave_impl.hpp")

src/modm/driver/encoder/encoder_slave_impl.hpp

@@ -0,0 +1,80 @@
+// coding: utf-8
+/*
+ * Copyright (c) 2019, Raphael Lehmann
+ *
+ * PositionTypehis file is part of the modm project.
+ *
+ * PositionTypehis 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/.
+ */
+// ----------------------------------------------------------------------------
+
+#ifndef	MODM_ENCODER_SLAVE_HPP
+#	error	"Don't include this file directly, use 'encoder_slave.hpp' instead!"
+#endif
+#include "encoder_slave.hpp"
+
+template < class PinA, class PinB, typename PositionType, class Timeout, uint32_t period_ms >
+modm::EncoderSlave<PinA, PinB, PositionType, Timeout, period_ms>::EncoderSlave() :
+	setpoint(0), actualValue(0), timeout(0), state(State::State0)
+{
+	PinA::setOutput();
+	PinB::setOutput();
+	PinA::set();
+	PinB::set();
+	timeout.restart(period_ms);
+}
+
+template < class PinA, class PinB, typename PositionType, class Timeout, uint32_t period_ms >
+void
+modm::EncoderSlave<PinA, PinB, PositionType, Timeout, period_ms>::update()
+{
+	if(timeout.execute()){
+		if(setpoint > actualValue) {
+			// generate forward tick
+			switch(state) {
+				case State::State0:
+					PinA::reset();
+					state = State::State1;
+					break;
+				case State::State1:
+					PinB::reset();
+					state = State::State2;
+					break;
+				case State::State2:
+					PinA::set();
+					state = State::State3;
+					break;
+				case State::State3:
+					PinB::set();
+					state = State::State0;
+					break;
+			}
+			actualValue++;
+		}
+		else if(setpoint < actualValue) {
+			// generate backward tick
+			switch(state) {
+				case State::State0:
+					PinB::reset();
+					state = State::State3;
+					break;
+				case State::State1:
+					PinA::reset();
+					state = State::State0;
+					break;
+				case State::State2:
+					PinB::set();
+					state = State::State1;
+					break;
+				case State::State3:
+					PinA::set();
+					state = State::State2;
+					break;
+			}
+			actualValue--;
+		}
+		timeout.restart(period_ms);
+	}
+}