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Basic timers (TIM6&TIM7) RM0090

527/1422 Doc ID 018909 Rev 4

Figure 189. Counter timing diagram with prescaler division change from 1 to 2

Figure 190. Counter timing diagram with prescaler division change from 1 to 4

17.3.2 Counting mode

The counter counts from 0 to the auto-reload value (contents of the TIMx_ARR register),

then restarts from 0 and generates a counter overflow event.

An update event can be generate at each counter overflow or by setting the UG bit in the

TIMx_EGR register (by software or by using the slave mode controller).

The UEV event can be disabled by software by setting the UDIS bit in the TIMx_CR1

registers. In this way, no update event occurs until the UDIS bit has been written to 0,

however, the counter and the prescaler counter both restart from 0 (but the prescale rate

does not change). In addition, if the URS (update request selection) bit in the TIMx_CR1

CK_PSC

CNT_EN

Timer clock = CK_CNT

Counter register

Update event (UEV)

F9 FA FB FCF7

Prescaler control register

Write a new value in TIMx_PSC

01 02 03

Prescaler buffer

Prescaler counter

1 0 1 0 1 0 1