GMS81C50 Datasheet, PDF (56/99 Pages) Hynix Semiconductor – 8-BIT SINGLE CHIP MICROCONTROLLERS

HYUNDAI
GMS81C50 Series
(3) Timer0, Timer1
TIMER0 and TIMER1 have an up-counter. When value of
the up-counter reaches the content of Timer Data Register
(TDR), the up-counter is cleared to ``00 h``, and interrupt
(IFT0, IFT1) is occured at the next clock.
T0 Data
Registers
Value
T0 Value
Concurrence
Concurrence
Concurrence
0
CLEAR
CLEAR
CLEAR
INTERRUPT
INTERRUPT
INTERRUPT
IFT0
Interval period
Figure 11-13 Operatiion of Timer0
For Timer0, the internal clock (PS) and the external clock
(EC) can be selected as counter clock. But Timer1 and
Timer2 use only internal clock. As internal clock. Timer0
can be used as internal-timer which period is determined
by Timer Data Register (TDR). Chosen as external
clock, Timer0 executes as event-counter. The counter ex-
ecution of Timer0 and Timer1 is controlled by T0CN,
T0ST, CAP0, T1CN, T1ST, of Timer Mode Register TM0
and TM1. T0CN, T1CN are used to stop and start Timer0
and Timer1 without clearing the counter. T0ST, T1ST is
used to clear the counter. For clearing and starting the
counter, T0ST or T1ST should be temporarily set to ``0``
and then set to ``1``. T0CN, T1CN, T0ST and T1ST
should be set ``1``, when Timer counting-up. Controlling
of CAP0 enables Timer0 as input capture. By program-
ming of CAP0 to ``1``, the period of signal from INT2 can
be measured and then, event counter value for INT2 can
be read. During counting-up, value of counter can be read.
Timer execution is stopped by the reset signal (RESET
= ``L``)
Note: In the process of reading 16-bit Timer Data, first
read the upper 8-bit data. Then read the lower 8-bit data,
and read the upper 8-bit data again. If the earlier read up-
per 8-bit data are matched with the later read upper 8-bit
data, read 16-bit data are correct. If not, caution should be
taken in the selection of upper 8-bit data.
(Example)
1) Upper 8-bit Read 0A 0A
2) Lower 8-bit Read FF 01
3) Upper 8-bit Read 0B 0B
=====================
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0AFF 0B01
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