Add: initial (working) blinky light program

.gitmodules

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+[submodule "lib/libopencm3"]
+	path = lib/libopencm3
+	url = https://github.com/libopencm3/libopencm3
+[submodule "lib/FreeRTOS"]
+	path = lib/FreeRTOS
+	url = https://github.com/FreeRTOS/FreeRTOS

Makefile

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+NAME=blinky
+
+PREFIX?=arm-none-eabi-
+CC=$(PREFIX)gcc
+AS=$(PREFIX)as
+OBJCOPY=$(PREFIX)objcopy
+
+VPATH=src
+
+.SECONDARY:
+
+clean:
+	rm -f lib/libopencm3/lib/libopencm3_stm32f4.a
+	rm -f $(NAME).bin
+	rm -f $(NAME).elf
+	rm -f $(NAME).o
+
+clobber:
+	rm -f lib/libopencm3/lib/libopencm3_stm32f4.a
+	rm -f $(NAME).bin
+	$(MAKE) -C lib/libopencm3 clean
+
+libopencm3:
+	$(MAKE) -C lib/libopencm3 TARGETS=stm32/f4
+
+flash: $(NAME).bin
+	st-flash write $(NAME).bin 0x8000000
+
+all: libopencm3 $(NAME).bin
+
+%.o: %.c
+	$(CC) -Og -g -Wall -std=c99 -mthumb -mcpu=cortex-m4 -mfloat-abi=hard -Ilib/libopencm3/include -DSTM32F4 -c $< -o $@
+
+%.elf: %.o
+	$(CC) --static -nostartfiles -Tnucleo-f411re.ld -mthumb -mcpu=cortex-m4 -mfloat-abi=hard -Llib/libopencm3/lib $< -lopencm3_stm32f4 -o $@
+
+%.bin: %.elf
+	$(OBJCOPY) $< -O binary $@

README.org

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+#+Title: Oof Oww Ouch... My Blinky Arm

compile_commands.json

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+[
+  {
+    "arguments": [
+      "/usr/bin/arm-none-eabi-gcc",
+      "-Og",
+      "-g",
+      "-Wall",
+      "-std=c99",
+      "-mthumb",
+      "-mcpu=cortex-m4",
+      "-mfloat-abi=hard",
+      "-Ilib/libopencm3/include",
+      "-DSTM32F4",
+      "-c",
+      "-o",
+      "blinky.o",
+      "src/blinky.c"
+    ],
+    "directory": "/home/fckr/progs/stm32/blinky-arm",
+    "file": "/home/fckr/progs/stm32/blinky-arm/src/blinky.c",
+    "output": "/home/fckr/progs/stm32/blinky-arm/blinky.o"
+  }
+]

lib/FreeRTOS

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+Subproject commit 82b4c249aa52239e90462fff0ebd628e51d6046c

lib/libopencm3

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+Subproject commit 1f3abd43763fa39d23e737602b6d0011a45c70b2

nucleo-f411re.ld

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+/*
+ * This file is part of the libopencm3 project.
+ *
+ * Copyright (C) 2009 Uwe Hermann <uwe@hermann-uwe.de>
+ * Copyright (C) 2011 Stephen Caudle <scaudle@doceme.com>
+ *
+ * This library is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Lesser General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this library.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+/* Linker script for Nucleo F411RE  (STM32F411RE, 512K flash, 128K RAM). */
+
+/* Define memory regions. */
+MEMORY
+{
+	rom (rx) : ORIGIN = 0x08000000, LENGTH = 512K
+	ram (rwx) : ORIGIN = 0x20000000, LENGTH = 128K
+}
+
+/* Include the common ld script. */
+INCLUDE cortex-m-generic.ld
+

src/blinky.c

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+#include <libopencm3/stm32/rcc.h>
+#include <libopencm3/stm32/gpio.h>
+
+static void gpio_setup(void) {
+  /* Enable GPIOC clock */
+  rcc_periph_clock_enable(RCC_GPIOA);
+
+  /* Set GPIO to output push-pull */
+  gpio_mode_setup(GPIOA, GPIO_MODE_OUTPUT, GPIO_PUPD_NONE, GPIO5);
+}
+
+int main(void) {
+  int i;
+
+  gpio_setup();
+
+  while (1) {
+    gpio_toggle(GPIOA, GPIO5);
+    for (i = 0; i < 1000000; i++) {
+      __asm__("nop");
+    }
+  }
+  return 0;
+}