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Rev. 1.00
188 of 486
July 31, 2018
32-Bit Arm
®
Cortex
®
-M0+ MCU
HT32F50231/HT32F50241
13 General-Purpose T
imer (GPTM)
13 General-Purpose T
imer (GPTM)
Center-Aligned Counting
In the center-aligned counting mode, the counter counts up from 0 to the counter-reload value
and then counts down to 0 alternatively. The Timer module generates an overflow event when the
counter counts to the counter-reload value in the up-counting mode and generates an underflow
event when the counter counts to 0 in the down-counting mode. The counting direction bit DIR in
the CNTCFR register is read-only and indicates the counting direction when in the center-aligned
mode. The counting direction is updated by hardware automatically.
Setting the UEVG bit in the EVGR register will initialize the counter value to 0 irrespective of
whether the counter is counting up or down in the center-aligned counting mode.
The UEVIF bit in the INTSR register will be set to 1 when an overflow or underflow event or both
of them occur according to the CMSEL field setting in the CNTCFR register.
CK_PSC
CNT_EN
F3
F4
4
CK_CNT
F2
F5
CNTR
CRR Shadow
Register
CRR
4
F5
4
3
2
1
0
Counter Underflow
Update Event Flag
Software clearing
Write a new value
Counter Overflow
1
2
3
Software clearing
Figure 33. Center-aligned Counting Example