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STM32F107 TIM4: writes to CR1 also write to DMAR

Question asked by Wood.Robert on Oct 27, 2016
Latest reply on Oct 27, 2016 by waclawek.jan

Has anyone seen this bizarre behaviour where if you write to a timer's CR1 register it also writes to the DMAR register?

I have this utterly bizarre thing going on where my timer interrupt was going off at the wrong interval and nothing I did would stop it.

Eventually I noticed the DMAR register had 5 in it which, if I manually changed it to 0 with the debugger, stopped the interrupt going off.

Every time I change the CR1 register I have to write 0 to the DMAR register otherwise I get incorrect interrupts. The big problem is that if I then write 0 to DMAR to stop getting these 1ms interrupts (no idea why that should happen either), then the timer is switched off.

Is this a known bug? More to the point, how on earth do I stop this happening please?

I can't see anything in the errata.