Advanced-control timers (TIM1/TIM8/TIM20) RM0440
1126/2126 RM0440 Rev 4
Figure 309. Generation of 2 phase-shifted PWM signals with 50% duty cycle
28.3.15 Combined PWM mode
Combined PWM mode allows two edge or center-aligned PWM signals to be generated with
programmable delay and phase shift between respective pulses. While the frequency is
determined by the value of the TIMx_ARR register, the duty cycle and delay are determined
by the two TIMx_CCRx registers. The resulting signals, tim_ocxrefc, are made of an OR or
AND logical combination of two reference PWMs:
– tim_oc1refc (or tim_oc2refc) is controlled by TIMx_CCR1 and TIMx_CCR2
– tim_oc3refc (or tim_oc4refc) is controlled by TIMx_CCR3 and TIMx_CCR4
Combined PWM mode can be selected independently on two channels (one tim_ocx output
per pair of CCR registers) by writing ‘1100’ (Combined PWM mode 1) or ‘1101’ (Combined
PWM mode 2) in the OCxM bits in the TIMx_CCMRx register.
When a given channel is used as combined PWM channel, its complementary channel must
be configured in the opposite PWM mode (for instance, one in Combined PWM mode 1 and
the other in Combined PWM mode 2).
Note: The OCxM[3:0] bit field is split into two parts for compatibility reasons, the most significant
bit is not contiguous with the 3 least significant ones.
Figure 310 represents an example of signals that can be generated using combined PWM
mode, obtained with the following configuration:
– Channel 1 is configured in Combined PWM mode 2,
– Channel 2 is configured in PWM mode 1,
– Channel 3 is configured in Combined PWM mode 2,
– Channel 4 is configured in PWM mode 1.
MSv62329V1
Counter register
tim_oc1refc
CCR1=0
CCR2=8
CCR3=3
CCR4=5
01234567 012345678 11
tim_oc3refc
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