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AT32F413
Series Reference Manual
2022.06.27
Page 208
Rev 2.00
Figure 14-31 Counting in external clock mode A
30
COUNTER
OVFIF
TMR_CLK
110
STIS[2:0]
Clear
CNT_CLK
C2IRAW
000
C2IF[2:0]
31
32
0
1
2
3
4
Internal trigger input (ISx)
Timer synchronization allows interconnection between several timers. The TMR_CLK of one timer can
be provided by the TRGOUT signal output by another timer. Set the STIS[2: 0] bit to select internal
trigger signal to enable counting.
Each timer consists of a 16-bit prescaler, which is used to generate the CK_CNT that enables the counter
to count. The frequency division relationship between the CK_CNT and TMR_CLK can be adjusted by
setting the value of the TMRx_DIV register. The prescaler value can be modified at any time, but it takes
effect only when the next overflow event occurs.
Table 14-6
TMRx internal trigger connecti on
Slave controler
IS0
(STIS=000)
IS1
(STIS = 001)
IS2
(STIS = 010)
IS3
(STIS = 011)
TMR9
TMR2
TMR3
TMR10_OC
TMR11_OC
Note: If there is no corresponding timer in a device, the corresponding trigger signal ISx is not present.
Figure 14-32
Counter timing with prescaler value changing from 1 to 4
TMR_CLK
CK_CNT
COUNTER
OVFIF
DIV[15
:
0]
18
17
19
1A
1B
1C
0
3
00
01
Clear
PR[15
:
0]
1C
14.2.3.2 Counting mode
The general-purpose timer consists of a 16-bit counter supporting upcounting mode. The TMRx_PR
register is loaded with the counter value. The value in the TMRx_PR is immediately moved to the shadow
register by deault. When the periodic buffer is enabled (PRBEN=1), the value in the TMRx_PR register
is transferred to the shadow register only at an overflow event. The OVFEN and OVFS bits are used to
configure the overflow event.
Settng TMREN=1 to enable the timer to start counting. Base on synchronization logic, however, the
actual enable signal TMR_EN is set 1 clock cycle after the TMREN is set.
Upcounting mode
In upcounting mode, the counter counts from 0 to the value programmed in the TMRx_PR register, then
restarts from 0, and generates a counter overflow event, with the OVFIF bit being set to 1. If the overflow
event is disabled, the counter is no longer reloaded with the preload value and period value at a counter