STM32F101xx, STM32F102xx, STM32F103xx, STM32F105xx and ...

RM0008
General-purpose timer (TIMx)
As in the previous example, you can initialize both counters before starting counting.
Figure 143 shows the behavior with the same configuration as in Figure 142 but in trigger
mode instead of gated mode (SMS=110 in the TIM2_SMCR register).
Figure 143. Triggering timer 2 with Enable of timer 1
CK_INT
TIMER1-CEN=CNT_EN
TIMER1-CNT_INIT
TIMER1-CNT
75 00 01
02
TIMER2-CNT
CD 00 E7 E8 E9 EA
TIMER2-CNT_INIT
TIMER2
write CNT
TIMER 2-TIF
Write TIF=0
Using one timer as prescaler for another timer
For example, you can configure Timer 1 to act as a prescaler for Timer 2. Refer to
Figure 139 for connections. To do this:
●
●
●
●
●
●
Configure Timer 1 master mode to send its Update Event (UEV) as trigger output
(MMS=010 in the TIM1_CR2 register). then it outputs a periodic signal on each counter
overflow.
Configure the Timer 1 period (TIM1_ARR registers).
Configure Timer 2 to get the input trigger from Timer 1 (TS=000 in the TIM2_SMCR
register).
Configure Timer 2 in external clock mode 1 (SMS=111 in TIM2_SMCR register).
Start Timer 2 by writing ‘1’ in the CEN bit (TIM2_CR1 register).
Start Timer 1 by writing ‘1’ in the CEN bit (TIM1_CR1 register).
Starting 2 timers synchronously in response to an external trigger
In this example, we set the enable of timer 1 when its TI1 input rises, and the enable of
Timer 2 with the enable of Timer 1. Refer to Figure 139 for connections. To ensure the
Doc ID 13902 Rev 9 353/995