RM0444 Rev 5 673/1390
RM0444 General-purpose timers (TIM2/TIM3/TIM4)
701
22.4.3 TIMx slave mode control register (TIMx_SMCR)(x = 2 to 4)
Address offset: 0x08
Reset value: 0x0000 0000
31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
Res. Res. Res. Res. Res. Res. Res. Res. Res. Res. TS[4:3] Res. Res. Res. SMS[3]
rw rw rw
1514131211109876543210
ETP ECE ETPS[1:0] ETF[3:0] MSM TS[2:0] OCCS SMS[2:0]
rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw
Bits 31:22 Reserved, must be kept at reset value.
Bits 19:17 Reserved, must be kept at reset value.
Bit 15 ETP: External trigger polarity
This bit selects whether ETR or ETR
is used for trigger operations
0: ETR is non-inverted, active at high level or rising edge
1: ETR is inverted, active at low level or falling edge
Bit 14 ECE: External clock enable
This bit enables External clock mode 2.
0: External clock mode 2 disabled
1: External clock mode 2 enabled. The counter is clocked by any active edge on the ETRF
signal.
Note: Setting the ECE bit has the same effect as selecting external clock mode 1 with TRGI
connected to ETRF (SMS=111 and TS=00111).
It is possible to simultaneously use external clock mode 2 with the following slave
modes: reset mode, gated mode and trigger mode. Nevertheless, TRGI must not be
connected to ETRF in this case (TS bits must not be 00111).
If external clock mode 1 and external clock mode 2 are enabled at the same time, the
external clock input is ETRF.
Bits 13:12 ETPS[1:0]: External trigger prescaler
External trigger signal ETRP frequency must be at most 1/4 of CK_INT frequency. A
prescaler can be enabled to reduce ETRP frequency. It is useful when inputting fast external
clocks.
00: Prescaler OFF
01: ETRP frequency divided by 2
10: ETRP frequency divided by 4
11: ETRP frequency divided by 8
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