GD32W51x User Manual
481
Reset value: 0x0000 0000
This register has to be accessed by word (32-bit).
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
Reserved
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
0
ETP
SMC1
ETPSC[1:0]
ETFC[3:0]
MSM
TRGS[2:0]
Reserved
SMC[2:0]
rw
rw
rw
rw
rw
rw
rw
Bits
Fields
Descriptions
31:16
Reserved
Must be kept at reset value.
15
ETP
External trigger polarity
This bit specifies the polarity of ETI signal
0: ETI is active at high level or rising edge.
1: ETI is active at low level or falling edge.
14
SMC1
Part of SMC for enable External clock mode1.
In external clock mode 1, the counter is clocked by any active edge on the ETIF
signal.
0: External clock mode 1 disabled
1: External clock mode 1 enabled.
It is possible to simultaneously use external clock mode 1 w ith the restart mode,
pause mode or event mode. But the TRGS bits mus
t not be 3’b111 in this case.
The external clock input w ill be ETIF if external clock mode 0 and external clock
mode 1 are enabled at the same time.
Note: External clock mode 0 enable is in this register’s SMC bit-filed.
13:12
ETPSC[1:0]
External trigger prescaler
The frequency of external trigger signal ETI must not be at higher than 1/4 of
TIMER_CK frequency. When the external trigger signal is a fast clock, the prescaler
can be enabled to reduce ETI frequency.
00: Prescaler disable
01: ETI frequency w ill be divided by 2
10: ETI frequency w ill be divided by 4
11: ETI frequency w ill be divided by 8
11:8
ETFC[3:0]
External trigger filter control
An event counter is used in the digital filter, in w hich a transition on the output occurs
after N input events. This bit-field specifies the frequency used to sample ETI signal
and the length of the digital filter applied to ETI.
0000: Filter disabled. f
SAMP
= f
DTS
, N=1.
0001: f
SAMP
= f
CK_TIMER
, N=2.
0010: f
SAMP
= f
CK_TIMER
, N=4.