[examples] Add example for Nucleo F042K6 with vector table in ram

Author: chris-durand

examples/nucleo_f042k6/vector_table_ram/main.cpp

@@ -0,0 +1,55 @@
+/*
+ * 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>
+
+using namespace Board;
+
+// Blink LED with timer 14 interrupt. A custom handler is configured at runtime
+// in the vector table located in SRAM.
+
+// If the LED is blinking with a period of 1 second, the vector table has been
+// successfully relocated to ram.
+// Set the option "modm:platform:core:vector_table_location" in project.xml
+// to place the vector table in ram on F0 devices without vector table relocation
+// support in the Cortex M0 core.
+
+static void tim14Handler()
+{
+	Timer14::acknowledgeInterruptFlags(Timer14::InterruptFlag::Update);
+	LedD13::toggle();
+}
+
+int
+main()
+{
+	Board::initialize();
+	LedD13::setOutput();
+
+	// Set custom handler, only works if vector table is in RAM
+	NVIC_SetVector(TIM14_IRQn, reinterpret_cast<uintptr_t>(&tim14Handler));
+
+	Timer14::enable();
+	Timer14::setMode(Timer14::Mode::UpCounter);
+	Timer14::setPeriod<Board::SystemClock>(500'000 /* us */);
+	Timer14::applyAndReset();
+	Timer14::start();
+	Timer14::enableInterrupt(Timer14::Interrupt::Update);
+	Timer14::enableInterruptVector(true, 5);
+
+	uint32_t counter{0};
+	while (true)
+	{
+		modm::delay(100ms);
+		MODM_LOG_INFO << "loop: " << counter++ << modm::endl;
+	}
+
+	return 0;
+}

examples/nucleo_f042k6/vector_table_ram/project.xml

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+<library>
+  <extends>modm:nucleo-f042k6</extends>
+  <options>
+    <option name="modm:build:build.path">../../../build/nucleo_f042k6/vector_table_ram</option>
+    <option name="modm:platform:core:vector_table_location">ram</option>
+  </options>
+  <modules>
+    <module>modm:build:scons</module>
+    <module>modm:platform:timer:14</module>
+  </modules>
+</library>