DocID018909 Rev 11
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RM0090
General-purpose timers (TIM2 to TIM5)
640
Figure 152. Counter timing diagram, Update event with ARPE=1 (counter underflow)
Figure 153. Counter timing diagram, Update event with ARPE=1 (counter overflow)
18.3.3 Clock
selection
The counter clock can be provided by the following clock sources:
•
Internal clock (CK_INT)
•
External clock mode1: external input pin (TIx)
•
External clock mode2: external trigger input (ETR) available on TIM2, TIM3 and TIM4
only.
•
Internal trigger inputs (ITRx): using one timer as prescaler for another timer, for
example, you can configure Timer to act as a prescaler for Timer 2. Refer to
one timer as prescaler for another timer on page 613
00
CNT_EN
Timer clock = CK_CNT
Counter register
Update interrupt flag (UIF)
Counter underflow
Update event (UEV)
01 02 03 04 05 06 07
05 04 03 02 01
06
Auto-reload preload register
FD
36
Write a new value in TIMx_ARR
Auto-reload active register
FD
36
CK_INT
36
CNT_EN
Timer clock = CK_CNT
Counter register
Update interrupt flag (UIF)
Counter overflow
Update event (UEV)
35 34 33 32 31 30 2F
F8 F9 FA FB FC
F7
Auto-reload preload register
FD
36
Write a new value in TIMx_ARR
Auto-reload active register
FD
36
CK_INT