Create I2S audio DAC example for STM32F4-Discovery board

Author: rleh

examples/stm32f4_discovery/audio_i2s/main.cpp

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+/*
+ * Copyright (c) 2021, Raphael Lehmann
+ * Copyright (c) 2021, Christopher Durand
+ *
+ * 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/.
+ */
+// ----------------------------------------------------------------------------
+
+#include <modm/board.hpp>
+#include <modm/driver/dac/cs43l22.hpp>
+
+#include <array>
+#include <cmath>
+#include <limits>
+#include <numbers>
+
+using namespace Board;
+
+
+template<typename T, std::size_t length>
+constexpr auto computeSinTable(uint8_t cycles=1)
+{
+	std::array<T, length> data{};
+	constexpr auto HalfOutput = std::numeric_limits<T>::max() / 2; // 16 bit full scale
+	for (size_t i = 0; i < data.size(); ++i) {
+		constexpr auto pi = std::numbers::pi_v<float>;
+		data[i] = HalfOutput * (1 + sin(i * (2*pi / data.size() * cycles)));
+	}
+	return data;
+}
+
+int
+main()
+{
+	initialize();
+
+	Dma1::enable();
+	Dma2::enable();
+	initializeCs43</*samplerate=*/48_kHz>();
+
+	modm::Cs43l22<cs43::I2cMaster, cs43::I2sMaster> audioDac{cs43::I2CAddress};
+
+	audioDac.setMasterVolume(-600);
+
+	constexpr std::size_t bufferSize = 480;
+	auto bufferA = computeSinTable<uint16_t, bufferSize>(1);
+	auto bufferB = computeSinTable<uint16_t, bufferSize>(2);
+
+	cs43::I2sMaster::setTxBufferAddresses(uintptr_t(bufferA.data()), uintptr_t(bufferB.data()), bufferSize);
+	cs43::I2sMaster::start();
+
+	LedOrange::set();
+	LedRed::set();
+
+	uint8_t counter{3};
+
+	while (true)
+	{
+		while(cs43::I2sMaster::isBuffer1Active()) ; // wait until bufferA is not used
+		bufferA = computeSinTable<uint16_t, bufferSize>(counter);
+		counter++;
+
+		while(!cs43::I2sMaster::isBuffer1Active()) ; // wait until bufferb is not used
+		bufferB = computeSinTable<uint16_t, bufferSize>(counter);
+		counter++;
+
+		if (counter == 100) {
+			counter = 3;
+		}
+
+		LedBlue::toggle();
+	}
+
+	return 0;
+}

examples/stm32f4_discovery/audio_i2s/project.xml

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+<library>
+  <extends>modm:disco-f407vg</extends>
+  <options>
+    <option name="modm:build:build.path">../../../build/stm32f4_discovery/audio_i2s</option>
+  </options>
+  <modules>
+    <module>modm:build:scons</module>
+  </modules>
+</library>