6-Step Pwm Generation; Figure 91. 6-Step Generation, Com Example (Ossr=1) - ST STM32F101 series Reference Manual

RM0008
14.3.14

6-step PWM generation

When complementary outputs are used on a channel, preload bits are available on the
OCxM, CCxE and CCxNE bits. The preload bits are transferred to the shadow bits at the
COM commutation event. Thus you can program in advance the configuration for the next
step and change the configuration of all the channels at the same time. COM can be
generated by software by setting the COM bit in the TIMx_EGR register or by hardware (on
TRGI rising edge).
A flag is set when the COM event occurs (COMIF bit in the TIMx_SR register), which can
generate an interrupt (if the COMIE bit is set in the TIMx_DIER register) or a DMA request
(if the COMDE bit is set in the TIMx_DIER register).
Figure 91
in 3 different examples of programmed configurations.
describes the behavior of the OCx and OCxN outputs when a COM event occurs,

Figure 91. 6-step generation, COM example (OSSR=1)

counter (CNT)
(CCRx)
OCxREF
COM event
CCxE=1
CCxNE=0
OCxM=100 (forced inactive)
OCx
Example 1
OCxN
CCxE=1
CCxNE=0
OCxM=100 (forced inactive)
OCx
Example 2
OCxN
CCxE=1
CCxNE=0
OCxM=100 (forced inactive)
OCx
Example 3
OCxN
Advanced-control timers (TIM1&TIM8)
write OCxM to 100
Write CCxNE to 1
and OCxM to 101
write CCxNE to 0
and OCxM to 100
DocID13902 Rev 15
Write COM to 1
CCxE=1
CCxNE=0
OCxM=100
CCxE=0
CCxNE=1
OCxM=101
CCxE=1
CCxNE=0
OCxM=100
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