ht82k70e-l Holtek Semiconductor Inc., ht82k70e-l Datasheet - Page 21

• Manufacturer Part Number: ht82k70e-l
• Description: I/o Type 8-bit Otp Mcu
• Manufacturer: Holtek Semiconductor Inc.

that setting the timer enable bit high to turn the timer on,
should only be executed after the timer mode bits have
been properly setup. Setting the timer enable bit high to-
gether with a mode bit modification, may lead to improper
timer operation if executed as a single timer control regis-
ter byte write instruction.
When the Timer/Event counter overflows, its corre-
sponding interrupt request flag in the interrupt control
register will be set. If the timer interrupt is enabled this
will in turn generate an interrupt signal. However irre-
spective of whether the timer interrupt is enabled or not,
a Timer/Event counter overflow will also generate a
wake-up signal if the device is in a Power-down condi-
tion. This situation may occur if the Timer/Event Counter
is in the Event Counting Mode and if the external signal
continues to change state. In such a case, the
Timer/Event Counter will continue to count these exter-
nal events and if an overflow occurs the device will be
org 04h
reti
org 08h
jmp tmr0int
org 0ch
jmp tmr1int
org 20h
;internal Timer/Event Counter 0 interrupt routine
tmr0int:
; Timer/Event Counter 0 main program placed here
;internal Timer/Event Counter 1 interrupt routine
tmr1int:
; Timer/Event Counter 1 main program placed here
begin:
;setup Timer/Event Counter 0 registers
mov a,0e8h
mov tmr0l,a
mov a,09bh
mov tmr0h,a
mov a,080h
mov tmr0c,a
;setup Timer/Event Counter 1 registers
mov a,09bh
mov tmr1l,a
mov a,0e8h
mov tmr1h,a
mov a,080h
mov tmr1c,a
; setup interrupt register
mov a,00dh
mov intc,a
set tmr0c.4
set tmr1c.4
Rev. 1.00
:
:
:
:
reti
:
:
:
reti
:
:
; external interrupt vector
; Timer/Event Counter 0 interrupt vector
; jump here when Timer/Event Counter 0 overflows
; Timer/Event Counter 1 interrupt vector
; jump here when Timer/Event Counter 1 overflows
; main program
; setup low byte preload value for Timer/Event Counter 0
; low byte must be setup before high byte
; setup high byte preload value for Timer/Event Counter 0
;
; setup Timer control register TMR0C
; Timer/Event Counter 0 has no prescaler and clock source is f
; setup low byte preload value for Timer/Event Counter 1
; low byte must be setup before high byte
; setup high byte preload value for Timer/Event Counter 1
;
; setup Timer control register TMR1C
; Timer/Event Counter 1 has no prescaler and clock source is f
; enable master interrupt and timer interrupts
; start Timer/Event Counter 0
; start Timer/Event Counter 1
21
note mode bits must be previously setup
note mode bits must be previously setup
woken up from its Power-down condition. To prevent
such a wake-up from occurring, the timer interrupt re-
quest flag should first be set high before issuing the
HALT instruction to enter the Power Down Mode.
Timer Program Example
This program example shows how the Timer/Event
Counter registers are setup, along with how the inter-
rupts are enabled and managed. Note how the
Timer/Event Counter is turned on, by setting bit 4 of the
Timer Control Register. The Timer/Event Counter can
be turned off in a similar way by clearing the same bit.
This example program sets the Timer/Event Counter
tobe in the timer mode, which uses the internal system
clock as the clock source.
HT82K70E-L/HT82K76E-L
September 15, 2009
SYS
SYS
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