Link against libopencm3

5 files changed, 69 insertions, 14 deletions

diff --git a/Makefile b/Makefile
index 4ef61dd..0b7e9c0 100644
--- a/Makefile
+++ b/Makefile
@@ -1,12 +1,23 @@
 
-.PHONY: all clean
+OBJS = main.o startup.o
+
+# tools
+PREFIX     ?= arm-none-eabi
+CC          = $(PREFIX)-gcc
+LD          = $(PREFIX)-gcc
+OBJCOPY     = $(PREFIX)-objcopy
 
-all:
+all: deps/libopencm3/lib/libopencm3_stm32f1.a
 	mkdir build
-	arm-none-eabi-gcc -O0 -c -g -mcpu=cortex-m3 -mthumb -o build/test_program.o src/test_program.c
-	arm-none-eabi-gcc -O0 -c -g -mcpu=cortex-m3 -mthumb -o build/startup.o src/startup.c
-	arm-none-eabi-ld -Tld/stm32.ld -o build/test_program.elf build/startup.o build/test_program.o
-	arm-none-eabi-objcopy -O binary build/test_program.elf build/test_program.bin
+	$(CC) -O0 -c -g -DSTM32F1 -Ideps/libopencm3/include -mcpu=cortex-m3 -mthumb -o build/main.o src/main.c
+	$(CC) -O0 -c -g -DSTM32F1 -Ideps/libopencm3/include -mcpu=cortex-m3 -mthumb -o build/startup.o src/startup.c
+	$(LD) --static -nostartfiles -mcpu=cortex-m3 -mthumb -msoft-float -Tld/stm32f103c8t6.ld -Ldeps/libopencm3/lib build/startup.o build/main.o -lopencm3_stm32f1 -o build/ledcontrol.elf
+	$(OBJCOPY) -O binary build/ledcontrol.elf build/ledcontrol.bin
+
+deps/libopencm3/lib/libopencm3_stm32f1.a:
+	make -C deps/libopencm3
 
 clean:
 	rm -rf build
+
+.PHONY: all clean
diff --git a/README.md b/README.md
index dad276d..0306080 100644
--- a/README.md
+++ b/README.md
@@ -3,3 +3,8 @@
 
 A firmware project for the STM32F103C8T6 to control LED strips.
 
+## External References
+
+- Nice [Tutorial](https://jacobmossberg.se/posts/2018/08/11/run-c-program-bare-metal-on-arm-cortex-m3.html) about C programs on bare-metal ARM chips
+- Another useful [Tutorial](https://www.rhye.org/post/stm32-with-opencm3-0-compiling-and-uploading/) about STM32 programming with libopencm3
+
diff --git a/ld/stm32.ld b/ld/stm32f103c8t6.ld
index 9f74206..9f74206 100644
--- a/ld/stm32.ld
+++ b/ld/stm32f103c8t6.ld
diff --git a/src/main.c b/src/main.c
new file mode 100644
index 0000000..7a5290f
--- /dev/null
+++ b/src/main.c
@@ -0,0 +1,47 @@
+
+
+#include <libopencm3/stm32/rcc.h>
+#include <libopencm3/stm32/gpio.h>
+
+
+#define DELAY 1000000
+
+
+void clock_init(void);
+void gpio_init(void);
+void delay(void);
+
+
+int main(void)
+{
+	clock_init();
+	gpio_init();
+
+	while(1){
+		gpio_toggle(GPIOC, GPIO13);
+		delay();
+	}
+
+	return 0;
+}
+
+
+void clock_init(void)
+{
+	rcc_periph_clock_enable(RCC_GPIOC);  // for PC13 blinking
+}
+
+
+void gpio_init(void)
+{
+	gpio_set_mode(GPIOC, GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, GPIO13);
+	gpio_set(GPIOC, GPIO13);
+}
+
+
+void delay(void)
+{
+	for (int i = 0; i < DELAY; i++) {
+		__asm__("nop");
+	}
+}
diff --git a/src/test_program.c b/src/test_program.c
deleted file mode 100644
index 80f569b..0000000
--- a/src/test_program.c
+++ /dev/null
@@ -1,8 +0,0 @@
-static const int a = 7;
-static int b = 8;
-static int sum;
-
-void main()
-{
-    sum = a + b;
-}