Comment the setup a bit

Makefile

@@ -12,3 +12,7 @@ CPU_FLAGS := -mthumb -mcpu=cortex-m3 -msoft-float -mfix-cortex-m3-ldrd
 %.bin: %.elf
 	arm-none-eabi-objcopy -Obinary $*.elf $*.bin
 
+flash: main.bin
+	st-flash write /dev/stlinkv1_4 main.bin 0x08000000
+
+.PHONY: flash

main.c

@@ -18,10 +18,18 @@
 #define STM32F1 1			// Needed for libopencm3
 
 void setup (void) {			// All the blackbox code
+
+	// Set up clock
 	rcc_clock_setup_in_hse_8mhz_out_24mhz();
+
+	// Enable the two GPIOs
 	rcc_periph_clock_enable(RCC_GPIOC);
 	rcc_periph_clock_enable(RCC_GPIOA);
+
+	// GPIO C8 amd C9 are the two LEDs
 	gpio_set_mode(GPIOC, GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, GPIO8 | GPIO9);
+
+	// GPIO A0 is the push button
 	gpio_set_mode(GPIOA, GPIO_MODE_INPUT, GPIO_CNF_INPUT_FLOAT, GPIO0);
 }