RM0440 Rev 4 1257/2126
RM0440 General-purpose timers (TIM2/TIM3/TIM4/TIM5)
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bit in the TIMx_CCER register). The output pin can keep its level (OCXM=000), be set
active (OCxM=001), be set inactive (OCxM=010) or can toggle (OCxM=011) on match.
• Sets a flag in the interrupt status register (CCxIF bit in the TIMx_SR register).
• Generates an interrupt if the corresponding interrupt mask is set (CCXIE bit in the
TIMx_DIER register).
• Sends a DMA request if the corresponding enable bit is set (CCxDE bit in the
TIMx_DIER register, CCDS bit in the TIMx_CR2 register for the DMA request
selection).
The TIMx_CCRx registers can be programmed with or without preload registers using the
OCxPE bit in the TIMx_CCMRx register.
In output compare mode, the update event UEV has no effect on tim_ocxref and tim_ocx
output. The timing resolution is one count of the counter. Output compare mode can also be
used to output a single pulse (in One-pulse mode).
Procedure
1. Select the counter clock (internal, external, prescaler).
2. Write the desired data in the TIMx_ARR and TIMx_CCRx registers.
3. Set the CCxIE and/or CCxDE bits if an interrupt and/or a DMA request is to be
generated.
4. Select the output mode. For example:
a) Write OCxM = 0011 to toggle tim_ocx output pin when CNT matches CCRx
b) Write OCxPE = 0 to disable preload register
c) Write CCxP = 0 to select active high polarity
d) Write CCxE = 1 to enable the output
5. Enable the counter by setting the CEN bit in the TIMx_CR1 register.
The TIMx_CCRx register can be updated at any time by software to control the output
waveform, provided that the preload register is not enabled (OCxPE=0, else TIMx_CCRx
shadow register is updated only at the next update event UEV). An example is given in
Figure 387.
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