ST STM32F40 Series User Manual

Advanced-control timers (TIM1&TIM8) RM0090
365/1422 Doc ID 018909 Rev 4
Figure 89. Counter timing diagram, update event with ARPE=1 (counter underflow)
Figure 90. Counter timing diagram, Update event with ARPE=1 (counter overflow)
14.3.3 Repetition counter
Section 14.3.1: Time-base unit describes how the update event (UEV) is generated with
respect to the counter overflows/underflows. It is actually generated only when the repetition
counter has reached zero. This can be useful when generating PWM signals.
This means that data are transferred from the preload registers to the shadow registers
(TIMx_ARR auto-reload register, TIMx_PSC prescaler register, but also TIMx_CCRx
capture/compare registers in compare mode) every N+1 counter overflows or underflows,
where N is the value in the TIMx_RCR repetition counter register.
CK_PSC
00
CEN
Timer clock = CK_CNT
Counter register
Update interrupt flag (UIF)
Counter underflow
Update event (UEV)
01 02 03 04 05 06 0705 04 03 02 0106
Auto-reload preload register
FD 36
Write a new value in TIMx_ARR
Auto-reload active register
FD 36
CK_PSC
36
CEN
Timer clock = CK_CNT
Counter register
Update interrupt flag (UIF)
Counter overflow
Update event (UEV)
35 34 33 32 31 30 2FF8 F9 FA FB FCF7
Auto-reload preload register
FD 36
Write a new value in TIMx_ARR
Auto-reload active register
FD 36

ST STM32F40 Series Specifications

General

Brand	ST
Model	STM32F40 Series
Category	Microcontrollers
Language	English