RM0453 Rev 2 775/1454
RM0453 Advanced-control timer (TIM1)
822
Example: one wants to change the PWM configuration of the advanced-control timer TIM1
after a programmed delay each time a change occurs on the Hall inputs connected to one of
the TIMx timers.
• Configure 3 timer inputs ORed to the TI1 input channel by writing the TI1S bit in the
TIMx_CR2 register to ‘1’,
• Program the time base: write the TIMx_ARR to the max value (the counter must be
cleared by the TI1 change. Set the prescaler to get a maximum counter period longer
than the time between 2 changes on the sensors,
• Program the channel 1 in capture mode (TRC selected): write the CC1S bits in the
TIMx_CCMR1 register to ‘01’. The digital filter can also be programmed if needed,
• Program the channel 2 in PWM 2 mode with the desired delay: write the OC2M bits to
‘111’ and the CC2S bits to ‘00’ in the TIMx_CCMR1 register,
• Select OC2REF as trigger output on TRGO: write the MMS bits in the TIMx_CR2
register to ‘101’,
In the advanced-control timer TIM1, the right ITR input must be selected as trigger input, the
timer is programmed to generate PWM signals, the capture/compare control signals are
preloaded (CCPC=1 in the TIMx_CR2 register) and the COM event is controlled by the
trigger input (CCUS=1 in the TIMx_CR2 register). The PWM control bits (CCxE, OCxM) are
written after a COM event for the next step (this can be done in an interrupt subroutine
generated by the rising edge of OC2REF).
The Figure 183 describes this example.
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