General-purpose timers (TIM2/TIM3/TIM4)
RM0365
607/1080
DocID025202 Rev 7
Bits 6:4
OC1M
: Output compare 1 mode
These bits define the behavior of the output reference signal OC1REF from which OC1 and
OC1N are derived. OC1REF is active high whereas OC1 and OC1N active level depends
on CC1P and CC1NP bits.
0000: Frozen - The comparison between the output compare register TIMx_CCR1 and the
counter TIMx_CNT has no effect on the outputs.(this mode is used to generate a timing
base).
0001: Set channel 1 to active level on match. OC1REF signal is forced high when the
counter TIMx_CNT matches the capture/compare register 1 (TIMx_CCR1).
0010: Set channel 1 to inactive level on match. OC1REF signal is forced low when the
counter TIMx_CNT matches the capture/compare register 1 (TIMx_CCR1).
0011: Toggle - OC1REF toggles when TIMx_CNT=TIMx_CCR1.
0100: Force inactive level - OC1REF is forced low.
0101: Force active level - OC1REF is forced high.
0110: PWM mode 1 - In upcounting, channel 1 is active as long as TIMx_CNT<TIMx_CCR1
else inactive. In downcounting, channel 1 is inactive (OC1REF=‘0) as long as
TIMx_CNT>TIMx_CCR1 else active (OC1REF=1).
0111: PWM mode 2 - In upcounting, channel 1 is inactive as long as
TIMx_CNT<TIMx_CCR1 else active. In downcounting, channel 1 is active as long as
TIMx_CNT>TIMx_CCR1 else inactive.
1000: Retriggerable OPM mode 1 - In up-counting mode, the channel is active until a trigger
event is detected (on TRGI signal). Then, a comparison is performed as in PWM mode 1
and the channels becomes inactive again at the next update. In down-counting mode, the
channel is inactive until a trigger event is detected (on TRGI signal). Then, a comparison is
performed as in PWM mode 1 and the channels becomes inactive again at the next update.
1001: Retriggerable OPM mode 2 - In up-counting mode, the channel is inactive until a
trigger event is detected (on TRGI signal). Then, a comparison is performed as in PWM
mode 2 and the channels becomes inactive again at the next update. In down-counting
mode, the channel is active until a trigger event is detected (on TRGI signal). Then, a
comparison is performed as in PWM mode 1 and the channels becomes active again at the
next update.
1010: Reserved,
1011: Reserved,
1100: Combined PWM mode 1 - OC1REF has the same behavior as in PWM mode 1.
OC1REFC is the logical OR between OC1REF and OC2REF.
1101: Combined PWM mode 2 - OC1REF has the same behavior as in PWM mode 2.
OC1REFC is the logical AND between OC1REF and OC2REF.
1110: Asymmetric PWM mode 1 - OC1REF has the same behavior as in PWM mode 1.
OC1REFC outputs OC1REF when the counter is counting up, OC2REF when it is counting
down.
1111: Asymmetric PWM mode 2 - OC1REF has the same behavior as in PWM mode 2.
OC1REFC outputs OC1REF when the counter is counting up, OC2REF when it is counting
down.
Note:
1:
These bits can not be modified as long as LOCK level 3 has been programmed
(LOCK bits in TIMx_BDTR register) and CC1S=00 (the channel is configured in
output).
2:
In PWM mode, the OCREF level changes only when the result of the comparison
changes or when the output compare mode switches from “frozen” mode to “PWM”
mode.