Chapter 9
16-bit Timer
IX - 38 Prescaler
9.3.2 Setup Example
■ Setup Example
Timer function can be set by using timer 8 that generates the constant interrupts. Interrupts are generated every 1
ms by selecting the clock source IOCLK/8 and using the prescaler function. The oscillator frequency is set to 10
MHz, 6 multiplication and IOCLK=MCLK/2. A setup procedure with a description of each step is shown below:
Setup Procedure Description
(1) Stop the counter
TM8MD(0x0000A200)
bp6: TMLDE=0
bp7: TMCNE=0
(1) Set the TMLDE flag and TMCNE flag of the timer 8
mode register (TM8MD) to “0” to stop counting of the
timer 8
(2) Set the compare/capture register
TM8CA(0x0000A208)=0x0EA5
(2) Set the interrupt generation cycle to the timer 8
compare/capture A register (TM8CA). The setting is
3749 (0x0EA5) due to 3750 counts.
(3) Set the prescaler
TM8PSC(0x0000A214)
bp7: TMPSCNE=1
(3) Set the TMPSCNE flag of the prescaler control register
(TM8PSC) to “1” to enable the prescaler operation.
(4) Select the count clock source
TM8MD(0x0000A200)
bp2-0: TMCK2-0=001
(4) Select the count clock source (IOCLK) by the TMCK2-0
flag of the TM8MD register.
(5) Select the timer up/down
TM8MD(0x0000A200)
bp9-8: TMUD1-0=00
(5) Select the timer up count by the TMUD1-0 flag of the
TM8MD register.
(6) Set the timer counter clear enabled
TM8MD(0x0000A200)
bp11: TMCLE=1
(6) Set the TMCLE flag of the TM8MD register to “1” to
enable the clear operation of the TM8BC counter.
When the TM8CA register and the TM8BC counter
match, the TM8BC counter is cleared.
(7) Select the timer compare/capture A
operation mode
TM8MDA(0x0000A204)
bp7-6: TMAM1-0=00
(7) Set the function of the timer 8 compare/capture register
to the compare register (double buffer ) by the TMAM1
-0 flag of the timer 8 compare/capture A mode register
(TM8MDA).
(8) Initialize the timer 8
TM8MD(0x0000A200)
bp6: TMLDE=1
(8) Set the TMLDE flag of the TM8MD register to “1” to
initialize the timer 8. The value of the compare register
buffer is loaded into the TM8CA register. Reset the
TMLDE flag to “0” after setting.
(9) Start the timer operation
TM8MD(0x0000A200)
bp7: TMCNE=1
(9) Set the TMCNE flag of the TM8MD register to “1” to
operate the timer 8.
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