Figure 219. Gating Tim2 With Oc1Ref Of Tim1 - STMicroelectronics STM32WLEx Reference Manual

RM0461
1. Configure TIM1 master mode to send its Output Compare 1 Reference (OC1REF)
signal as trigger output (MMS=100 in the TIM1_CR2 register).
2. Configure the TIM1 OC1REF waveform (TIM1_CCMR1 register).
3. Configure TIM2 to get the input trigger from TIM1 (TS=00000 in the TIM2_SMCR
register).
4. Configure TIM2 in gated mode (SMS=101 in TIM2_SMCR register).
5. Enable TIM2 by writing '1 in the CEN bit (TIM_CR1 register).
6. Start TIM by writing '1 in the CEN bit (TIM1_CR1 register).
Note: The counter 2 clock is not synchronized with counter 1, this mode only affects the TIM2
counter enable signal.
TIM1-OC1REF
In the example in
started. So they start counting from their current value. It is possible to start from a given
value by resetting both timers before starting TIM1. Then any value can be written in the
timer counters. The timers can easily be reset by software using the UG bit in the
TIMx_EGR registers.
In the next example (refer to
master and starts from 0. TIM2 is the slave and starts from 0xE7. The prescaler ratio is the
same for both timers. TIM2 stops when TIM1 is disabled by writing '0 to the CEN bit in the
TIM1_CR1 register:
1. Configure TIM1 master mode to send its Output Compare 1 Reference (OC1REF)
signal as trigger output (MMS=100 in the TIM1_CR2 register).
2. Configure the TIM1 OC1REF waveform (TIM1_CCMR1 register).
3. Configure TIM2 to get the input trigger from TIM1 (TS=00000 in the TIM2_SMCR
register).
4. Configure TIM2 in gated mode (SMS=101 in TIM2_SMCR register).
5. Reset TIM1 by writing '1 in UG bit (TIM1_EGR register).
6. Reset TIM2 by writing '1 in UG bit (TIM2_EGR register).
7. Initialize TIM2 to 0xE7 by writing '0xE7' in the TIM2 counter (TIM2_CNTL).
8. Enable TIM2 by writing '1 in the CEN bit (TIM2_CR1 register).
9. Start TIM1 by writing '1 in the CEN bit (TIM1_CR1 register).
10. Stop TIM1 by writing '0 in the CEN bit (TIM1_CR1 register).

Figure 219. Gating TIM2 with OC1REF of TIM1

CK_INT
TIM1-CNT
FC
TIM2-CNT
3045
TIM2-TIF
Write TIF = 0
Figure 219, the TIM2 counter and prescaler are not initialized before being
Figure
RM0461 Rev 5
FD FE FF
3046 3047
220), we synchronize TIM1 and TIM2. TIM1 is the
General-purpose timer (TIM2)
00 01
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