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GD32E23x User Manual
292
alternate clock source controlled by SMC (TIMERx_SMCFG bit [2:0]).
SMC [2:0] == 3’b000. Internal timer clock CK_TIMER which is from module RCU.
The default internal clock source is the CK_TIMER used to drive the counter prescaler when
t
heSMC [2:0] == 3’b000. When the CEN is set, the CK_TIMER will be divided by PSC value
to generate PSC_CLK.
In this mode, the TIMER_CK, driven counter’s prescaler to count, is equal to CK_TIMER
which is from RCU.
If the SMC [2:0] in the TIMERx_SMCFG register are setting to an available value including
0x1, 0x2, 0x3 and 0x7, the prescaler is clocked by other clock sources selected by the TRGS
[2:0] in the TIMERx_SMCFG register and described as follows. When the SMC [2:0] bits are
set to 0x4, 0x5 or 0x6, the internal clock CK_TIMER is the counter prescaler driving clock
source.
Figure 14-32.
Timing chart of 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, driven counter’s prescaler to count, can be triggered by the event of rising
or falling edge on the external pin TIMERx_CH0/TIMERx_CH1. 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, driven 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