Change timers output compare mode

[Rafael1]

Hello,

I have a problem, I would like to change a timer output compare mode on my STM32G484xE microcontroller. I would like to switch between toggle and PWM mode 1. I do the whole thing with a small function for writing registers:

void ProgRegister(uint32_t *RegAddr, uint32_t Bits, uint32_t BitMask){
 *RegAddr = (*RegAddr & ~BitMask) | Bits;
}

This is how I switch to the different output compare modes:

//switch to toggle mode
ProgRegister((uint32_t*) &TIM1->CCMR1, TIM_CCMR1_OC1M_0 | TIM_CCMR1_OC1M_1, TIM_CCMR1_OC1M); // 0011 Toggle

//switch to pwm mode 1
ProgRegister((uint32_t*) &TIM1->CCMR1, TIM_CCMR1_OC1M_2 | TIM_CCMR1_OC1M_1, TIM_CCMR1_OC1M); // 0110 PWM Mode 1

The timer is initialized in toggle mode, and if I then want to set it to PMW1 mode, it remains in toggle mode. The LOCK bits are also not set, so I should be able to write to the registers.

Do you have any idea what my problem could be, so that the mode does not switch?

[waclawek.jan]

> it remains in toggle mode

How do you know?

Step through disasm of that function to see what happens at register level.

By casting to uint32_t * you removed volatile; I'm not sure if that's the problem.

JW

[TDK]

Consider using the standard MODIFY_REG macro instead. Does the same thing as your function but doesn't remove the volatile.

#define MODIFY_REG(REG, CLEARMASK, SETMASK)  WRITE_REG((REG), (((READ_REG(REG)) & (~(CLEARMASK))) | (SETMASK)))