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ML51/ML54/ML56
Sep. 01, 2020
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Tec
hnical Reference
Manual
6.5.4
Timer 3
Timer 3 is implemented simply as a 16-bit auto-reload, up-counting timer. The user can select the pre-
scale with T3PS[2:0] (T3CON[2:0]) and fill the reload value into RH3 and RL3 registers to determine
its overflow rate. User then can set TR3 (T3CON.3) to start counting. When the counter rolls over
FFFFH, TF3 (T3CON.4) is set as 1 and a reload is generated and causes the contents of the RH3 and
RL3 registers to be reloaded into the internal 16-bit counter. If ET3 (EIE1.1) is set as 1, Timer 3
interrupt service routine will be served. TF3 is auto-cleared by hardware after entering its interrupt
service routine.
Timer 3 can also be the baud rate clock source of both UARTs. For details, please see Section
6.9.3.2
RL3
TR3
(T3CON.3)
F
SYS
Internal 16-bit Counter
0
7
RH3
0
7
Timer 3
Overflow
Pre-scalar
(1/1~1/128)
T3PS[2:0]
(T3CON[2:0])
TF3
(T3CON.4)
Timer 3 Interrupt
Figure 6.5-8 Timer 3 Block Diagram
Following shows the Timer 3 control register.