Figure 206. Gating Tim2 With Oc1Ref Of Tim3 - ST STM32G0 1 Series Reference Manual

RM0444
1. Configure TIM3 master mode to send its Output Compare 1 Reference (OC1REF)
signal as trigger output (MMS=100 in the TIM3_CR2 register).
2. Configure the TIM3 OC1REF waveform (TIM3_CCMR1 register).
3. Configure TIM2 to get the input trigger from TIM3 (TS=00010 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 (TIM2_CR1 register).
6. Start TIM3 by writing '1 in the CEN bit (TIM3_CR1 register).
Note: The counter 2 clock is not synchronized with counter 1, this mode only affects the TIM2
counter enable signal.
TIM3-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 TIM3. 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 TIM3 is disabled by writing '0 to the CEN bit in the
TIM3_CR1 register:
1. Configure TIM3 master mode to send its Output Compare 1 Reference (OC1REF)
signal as trigger output (MMS=100 in the TIM3_CR2 register).
2. Configure the TIM3 OC1REF waveform (TIM3_CCMR1 register).
3. Configure TIM2 to get the input trigger from TIM3 (TS=00010 in the TIM2_SMCR
register).
4. Configure TIM2 in gated mode (SMS=101 in TIM2_SMCR register).
5. Reset TIM3 by writing '1 in UG bit (TIM3_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 TIM3 by writing '1 in the CEN bit (TIM3_CR1 register).
10. Stop TIM3 by writing '0 in the CEN bit (TIM3_CR1 register).

Figure 206. Gating TIM2 with OC1REF of TIM3

CK_INT
TIM3-CNT
FC
TIM2-CNT
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TIM2-TIF
Write TIF = 0
Figure 206, the TIM2 counter and prescaler are not initialized before being
Figure
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General-purpose timers (TIM2/TIM3/TIM4)
FD FE FF
3046 3047
207), we synchronize TIM3 and TIM2. TIM3 is the
00 01
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