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GD32A50x User Manual
462
Counter up counting
In this mode, the counter counts up continuously from 0 to the counter reload value, which is
defined in the TIMERx_CAR register, in a count-up direction. Once the counter reaches the
counter reload value, the counter will start counting up from 0 again. The update event is
generated at each counter overflow. The counting direction bit DIR in the TIMERx_CTL1
register should be set to 0 for the up counting mode.
When the update event is set by the UPG bit in the TIMERx_SWEVG register, the counter
value will be initialized to 0 and generates an update event.
If the UPDIS bit in TIMERx_CTL0 register is set, the update event is disabled.
When an update event occurs, all the shadow registers (auto reload register, prescaler
register) are updated.
The following figures show some examples of the counter behavior for different clock
prescaler factor when TIMERx_CAR=0x99.
Figure 18-64.
Timing chart of up counting mode, PSC=0/2
CEN
PSC_CLK
CNT_REG
94
95
96
97
98
99
0
1
2
3
4
5
6
7
Update event (UPE)
Update interrupt flag (UPIF)
CNT_REG
96
Update event (UPE)
Update interrupt flag (UPIF)
Hardware set
Software clear
Hardware set
PSC = 0
PSC = 2
TIMER_CK
8
PSC_CLK
97
98
99
0
1