GD32W51x User Manual
507
Figure 17-35. Normal mode, internal clock divided by 1
CK_TIMER
CEN
PSC_CLK = TIMER_CK
CNT_REG
Reload Pulse
17
18
19
20
21
22
update event
generate(UPG)
23
00
01
02
03
04
05
06
07
Update event (UPE)
SMC [2:0] == 3’b111(
external clock mode 0
). External input pin source
The TIMER_CK, which drives counter
’
s prescaler to count, can be triggered by the event of
rising or falling edge on the external pin TIMERx_CI0/TIMERx_CI1. This mode can be
selected by setting SMC [2:0] to 0x7 and the TRGS [2:0] to 0x4, 0x5 or 0x6.
And, the counter prescaler can also be driven by rising edge on the internal trigger input pin
ITI0/1/2/3. This mode can be selected by setting SMC [2:0] to 0x7 and the TRGS [2:0] to 0x0,
0x1, 0x2 or 0x3.
SMC1== 1’b1(
external clock mode 1
). External input pin source (ETI)
The TIMER_CK, which drives counter
’
s prescaler to count, can be triggered by the event of
rising or falling edge on the external pin ETI. This mode can be selected by setting the SMC1
bit in the TIMERx_SMCFG register to 1. The other way to select the ETI signal as the clock
source is to set the SMC [2:0] to 0x7 and the TRGS [2:0] to 0x7 respectively. Note that the
ETI signal is derived from the ETI pin sampled by a digital filter. When the ETI signal is
selected as clock source, the trigger controller including the edge detection circuitry will
generate a clock pulse on each ETI signal rising edge to clock the counter prescaler.
Prescaler
The prescaler can divide the timer clock (TIMER_CK) to the counter clock (PSC_CLK by any
factor between 1 and 65536. It is controlled through prescaler register (TIMERx_PSC) which
can be changed on the go but be taken into account at the next update event.