
General-purpose timer (TIM2)
RM0453
870/1454
RM0453 Rev 2
26.4.3
TIM2 slave mode control register (TIM2_SMCR)
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
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
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