General purpose timer (TIMx) UM0306
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13.5.3 Slave mode control register (TIMx_SMCR)
Address offset: 08h
Reset value: 0000h
1514131211109876543210
ETP ECE ETPS[1:0] ETF[3:0] MSM TS[2:0] Res. SMS[2:0]
rw rw rw rw rw rw rw rw rw rw rw rw rw rw rw
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 1: Setting the ECE bit has the same effect as selecting external clock mode 1 with
TRGI connected to ETRF (SMS=111 and TS=111).
Note 2: 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 111).
Note 3: 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: 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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