[example] Add SAMx7x ADC DMA example with hardware timer trigger

examples/samv71_xplained_ultra/adc/dma/main.cpp

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+/*
+ * Copyright (c) 2023, 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/io/iostream.hpp>
+#include <array>
+#include <atomic>
+
+/*
+ * ADC example with DMA and hardware timer trigger.
+ *
+ * Channels 0 and 8 are sampled 5 times in a sequence. The sampling is triggered
+ * by the Timer Counter Channel 0 TIOA output.
+ */
+
+using namespace modm::platform;
+using namespace modm::literals;
+
+using Ad2 = GpioA19::Ad; // channel 8, pin AD2 on board
+using Ad3 = GpioD30::Ad; // channel 0, pin AD3 on board
+
+constexpr size_t ChannelCount{2};
+constexpr size_t ChannelSamples{5};
+constexpr size_t TotalSamples{ChannelCount * ChannelSamples};
+
+std::array<uint16_t, TotalSamples> data{};
+std::atomic_bool samplingDone{false};
+
+BlockTransfer prepareDmaTransfer()
+{
+	BlockTransfer transfer;
+	transfer.setSourceAddress(Afec0::dataRegister());
+	transfer.setDestinationAddress(data.data());
+	transfer.setDataLength(TotalSamples);
+
+	Dma::ChannelConfig_t config;
+	Dma::TransferType_t::set(config, Dma::TransferType::Peripheral);
+	Dma::PeripheralDirection_t::set(config, Dma::PeripheralDirection::PeripheralToMemory);
+	// 16 bit data size
+	Dma::DataWidth_t::set(config, Dma::DataWidth::HalfWord);
+	// peripherals are connected to DMA AHB interface 1
+	Dma::SourceBusInterface_t::set(config, Dma::BusInterface::Bus1);
+	// data in RAM, all RAMs are connected to DMA AHB interface 0
+	Dma::DestinationBusInterface_t::set(config, Dma::BusInterface::Bus0);
+	// Auto-increment destination address after each sample
+	Dma::DestinationAddressingMode_t::set(config, Dma::AddressingMode::Incrementing);
+	// Transfer is triggered by Afec0 conversion
+	Dma::DmaRequest_t::set(config, DmaRequests::Afec<0>::Rx);
+	transfer.setConfiguration(config);
+
+	return transfer;
+}
+
+void startSampling(DmaChannel channel)
+{
+	channel.startTransfer(prepareDmaTransfer());
+	Afec0::enableHardwareTrigger(Afec0::Trigger::Tc0Tioa);
+}
+
+void initializeTimer()
+{
+	TimerChannel0::initialize();
+	// 32 kHz slow clock source
+	TimerChannel0::setClockSource(TimerChannel0::ClockSource::Slck);
+	TimerChannel0::setWaveformMode(true);
+	TimerChannel0::setWaveformSelection(TimerChannel0::WavSel::Up_Rc);
+
+	// 32768 Hz / 3277 = ~10 Hz sampling rate, 10 total samples => cycle ~1 Hz
+	TimerChannel0::setRegC(3277);
+	TimerChannel0::setRegA(100);
+	TimerChannel0::setTioaEffects(TimerChannel0::TioEffect::Set, TimerChannel0::TioEffect::Clear);
+
+	TimerChannel0::enable();
+	TimerChannel0::start();
+}
+
+void printSamples()
+{
+	MODM_LOG_INFO << "ADC Readings:\n";
+	MODM_LOG_INFO << "Channel 0 (AD3): ";
+	for (size_t i = 0; i < ChannelSamples; ++i) {
+		MODM_LOG_INFO << data[2 * i + 0] << " ";
+	}
+	MODM_LOG_INFO << '\n';
+	MODM_LOG_INFO << "Channel 8 (AD2): ";
+	for (size_t i = 0; i < ChannelSamples; ++i) {
+		MODM_LOG_INFO << data[2 * i + 1] << " ";
+	}
+	MODM_LOG_INFO << '\n';
+}
+
+int main()
+{
+	Board::initialize();
+	initializeTimer();
+
+	MODM_LOG_INFO << "ADC DMA Test\n";
+
+	Afec0::initialize<Board::SystemClock>();
+	Afec0::connect<Ad2::Ad, Ad3::Ad>();
+	Afec0::setChannels(Afec0::Channel::Ch0, Afec0::Channel::Ch8);
+
+	Dma::initialize();
+	const int priority = 5;
+	Dma::enableInterruptVector(priority);
+
+	auto channel = Dma::channel(0);
+	channel.enableInterrupts();
+	channel.enableInterruptFlag(DmaChannel::Interrupt::EndOfBlock);
+
+	channel.setInterruptHandler([](auto flags) {
+		if (flags & DmaChannel::Interrupt::EndOfBlock) {
+			Afec0::disableHardwareTrigger();
+			samplingDone = true;
+		}
+	});
+
+	startSampling(channel);
+
+	while (true) {
+		if (samplingDone) {
+			printSamples();
+			samplingDone = false;
+			startSampling(channel);
+		}
+	}
+}

examples/samv71_xplained_ultra/adc/dma/project.xml

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+<library>
+  <extends>modm:samv71-xplained-ultra</extends>
+  <options>
+    <option name="modm:build:build.path">../../../../build/samv71_xplained_ultra/adc/dma</option>
+  </options>
+  <modules>
+    <module>modm:build:scons</module>
+    <module>modm:platform:adc:0</module>
+    <module>modm:platform:dma</module>
+    <module>modm:platform:timer:0</module>
+  </modules>
+</library>