STM8L051F3, TIM4, what do I miss to make it run

[jgnoss]

I'm a bit rusty on 8Bit MCU's, more used to STM32 but have to get that STM8 project done.

I have a problem get TIM4 running, it might be I don't see the wood for all that trees.

It gets compiled using SDCC and the header file is slightly adopted for that.

here my code

#include "stm8l15x.h"

#define F_CPU 16000000UL

#define LED0_PIN	4
#define LED1_PIN	1

static inline void delay_ms(uint16_t ms) {
	uint32_t i;
	for (i = 0; i < ((F_CPU / 16000UL) * ms); i++)
		__asm__("nop");
}


void timer_isr(void) __interrupt(25) {
	GPIOC->ODR ^= (1 << LED0_PIN);
    TIM4->SR1 &= ~(1 << TIM4_SR1_UIF);
}


int main(void) {
    __asm__("rim");

	CLK->CKDIVR = 0x0;
	CLK->PCKENR1 = CLK_PCKENR1_TIM4;

	GPIOC->DDR |= (1 << (LED0_PIN)); // configure PB1 as output
	GPIOC->CR1 |= (1 << (LED0_PIN)); // push-pull mode

	GPIOB->DDR |= (1 << (LED1_PIN)); // configure PB1 as output
	GPIOB->CR1 |= (1 << (LED1_PIN)); // push-pull mode


    TIM4->PSCR = 0x02;
    TIM4->ARR = 0x02;

    TIM4->IER |= (1 << TIM4_IER_UIE); // Enable Update Interrupt
    TIM4->CR1 |= (1 << TIM4_CR1_CEN); // Enable TIM4
    TIM4->SR1 &= ~(1 << TIM4_SR1_UIF);



	while (1) {
		/* toggle pin every 250ms */

		GPIOB->ODR ^= (1 << LED1_PIN);
		//GPIOB->ODR ^= (1 << LED1_PIN);
		delay_ms(250);

	}
}