Remove logic from code -- we only blink

For some reason it is not needed now

Makefile

@@ -13,6 +13,6 @@ CPU_FLAGS := -mthumb -mcpu=cortex-m3 -msoft-float -mfix-cortex-m3-ldrd
 	arm-none-eabi-objcopy -Obinary $*.elf $*.bin
 
 flash: main.bin
-	st-flash write /dev/stlinkv1_4 main.bin 0x08000000
+	st-flash --reset write main.bin 0x08000000
 
 .PHONY: flash

README.md

@@ -1,35 +0,0 @@
-Setup
-===
-
-1. Need the "newlib" arm library (else there is no stdint.h &co.)
-
-```sh
-pacman -S arm-none-eabi-newlib
-```
-
-2. Get Libopencm3
-
-```sh
-git submodule init
-git submodule update
-```
-
-3. Generate headers in Libopencm3
-
-```sh
-cd libopencm3
-make
-cd ..
-```
-
-Possibly there are also some udev rules & co, I think they can be acquired from
-the `stlink` package.
-
-Usage
-===
-
-```
-make
-```
-
-It does everything. At least for STM32VLDISCOVERY board at my computer.

main.c

@@ -13,22 +13,27 @@
 #include <libopencm3/stm32/gpio.h>
 #include <libopencm3/stm32/f1/exti.h>
 #include <libopencm3/stm32/f1/nvic.h>
+#include <libopencm3/stm32/f1/timer.h>
 #include <stdbool.h>
 
 //#define DELAY 8000000		// Should be a second, or maybe not (second iff 8MHz clk, 1/3second if 24MHz clk)			// Too long!!
-#define DELAY 4000000		// This is bad -- it's a value that was found to be OK
 #define STM32F1 1			// Needed for libopencm3
 
-volatile enum {FORWARD, BACKWARD} direction;
-volatile bool running = false;
-
-void setup (void) {			// All the blackbox code
-
+void setup_system (void) {
 	// Set up clock
 	rcc_clock_setup_in_hse_8mhz_out_24mhz();
+}
 
-	// Enable the two GPIOs
+void setup_gpio_out (void) {
+	// Enable clock for GPIO C
 	rcc_periph_clock_enable(RCC_GPIOC);
+	// GPIO C8 amd C9 are the two LEDs
+	gpio_set_mode(GPIOC, GPIO_MODE_OUTPUT_50_MHZ, GPIO_CNF_OUTPUT_PUSHPULL, GPIO8 | GPIO9);
+
+}
+
+void setup_exti0_in (void) {
+	// Enable clock for GPIO A
 	rcc_periph_clock_enable(RCC_GPIOA);
 
 	// Enable AFIO (we need that to map GPIO to EXTI)
@@ -39,8 +44,6 @@ void setup (void) {			// All the blackbox code
 	// This one is for EXTI0 ~~ GPIOx0 pins
 	nvic_enable_irq(NVIC_EXTI0_IRQ);
 
-	// 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
 	// And we set it as a regular button and enable its interrupts in the next block
@@ -55,6 +58,32 @@ void setup (void) {			// All the blackbox code
 	exti_enable_request(EXTI0);
 }
 
+void setup_tim6_periodic_irq (void) {
+	// Enable clock
+	rcc_periph_clock_enable(RCC_TIM6);
+	
+	// Config:
+	// Set prescaler
+	timer_set_prescaler(TIM6, 65535);
+	// Set counter value
+	timer_set_period(TIM6, 183);
+
+	// Enable interrupts in NVIC
+	nvic_enable_irq(NVIC_TIM6_IRQ);
+	// Enable sending interrupts from the timer
+	timer_enable_irq(TIM6, TIM_DIER_UIE);
+
+	// Finally, enable the counter
+	timer_enable_counter(TIM6);
+}
+
+void setup (void) {
+	setup_system();
+	setup_gpio_out();
+	setup_exti0_in();
+	setup_tim6_periodic_irq();
+}
+
 // libopencm3 has a pre-declared interrupt handlers, so it needs to have this name
 void exti0_isr (void) {
 	// Clear the interrupt
@@ -62,36 +91,27 @@ void exti0_isr (void) {
 	// NB: For some reason it is at the begining in the examples
 	// It needs to be here (possibly because of reordering, when this was at the end, I usually got the interrupt twice).
 	
-	if (!running) {
-		direction = FORWARD;
+	// Toggle TIM6 in order to disable blinking
+	// Code inspired by libopencm3 source, since we cannot read the status otherwise…
+	TIM_CR1(TIM6) ^= TIM_CR1_CEN;
+}
+
+void tim6_isr (void) {
+	timer_clear_flag(TIM6, TIM_SR_UIF);
+	// Just change value of GPIO C9 (green LED)
+	uint16_t cur = gpio_get(GPIOC, GPIO9);
+	if (cur) {
+		gpio_clear(GPIOC, GPIO9);
 	} else {
-		direction = direction == FORWARD ? BACKWARD : FORWARD;
+		gpio_set(GPIOC, GPIO9);
 	}
-	running = true;
 }
 
 
 int main (void) {
 	setup();
 
-	// Array of what leds should be on
-	uint16_t states[4] = {0, GPIO9, GPIO8, GPIO9 | GPIO8};
-	char state = 0;
-	int i;
-
-	// Initial wait
-	while (!running) ;
-
-	while (true) {
-		for (i=0 ; i<DELAY ; i++) {
-			__asm ("nop");
-		}
-
-		state = (direction == FORWARD ? (state + 1)%4 : (/*state+4-1*/ state+3)%4 ); // New state
-
-		gpio_set(GPIOC, states[state]);
-		gpio_clear(GPIOC, (GPIO8 | GPIO9) ^ states[state]);
-	}
+	while (true) __asm ("wfi");
 	return 0;
 }