Hyundai Micro Electronics
GMS81C2020/GMS81C2120
15. TIMER / COUNTER
The GMS81C2020 and GMS81C2120 has two Timer/
Counter registers. Each module can generate an interrupt
to indicate that an event has occurred (i.e. timer match).
sponse to a 0-to-1 (rising & falling edge) transition at its
corresponding external input pin, EC0(Timer 0).
In addition the "capture" function, the register is increased
in response external interrupt same with timer function.
When external interrupt edge input, the count register is
captured into capture data register CDRx.
Timer 0 and Timer 1 can be used either the two 8-bit Tim-
er/Counter or one 16-bit Timer/Counter by combining
them.
In the "timer" function, the register is increased every in-
ternal clock input. Thus, one can think of it as counting in-
ternal clock input. Since a least clock consists of 2 and
most clock consists of 2048 oscillator periods, the count
rate is 1/2 to 1/2048 of the oscillator frequency in Timer0.
And Timer1 can use the same clock source too. In addition,
Timer1 has more fast clock source ( 1/1 to 1/8 ).
Timer1 is shared with "PWM" function and "Compare out-
put" function
It has seven operating modes: "8-bit timer/counter", "16-
bit timer/counter", "8-bit capture", "16-bit capture", "8-bit
compare output", "16-bit compare output" and "10-bit
PWM" which are selected by bit in Timer mode register
TMx as shown in Figure 15-1 and Table 12-1 .
In the "counter" function, the register is increased in re-
Timer 0 Mode Register
ADDRESS : D0H
RESET VALUE : --000000
-
-
CAP0
T0CK2
T0CK1
T0CK0
T0CN
T0ST
TM0
CAP0
Capture mode selection bit.
0 : Disables Capture
1 : Enables Capture
T0CN
T0ST
Continue control bit
0 : Stop counting
1 : Start counting continuously
T0CK[2:0]
Input clock selection
Start control bit
0 : Stop counting
1 : Counter register is cleared and start again
000 : fXI 2100 : fXI 128
÷
÷
001 : fXI 4101 : fXI 512
÷
÷
010 : fXI 8110 : fXI 2048
÷
÷
011 : fXI 32111 : External Event (EC0)
÷
Timer 1 Mode Register
ADDRESS : D2H
RESET VALUE : 00000000
POL
16BIT
PWM1E
CAP1
T1CK1
T1CK0
T1CN
T1ST
TM1
POL
PWM Output Polarity
0 :Duty active low
1 : Duty active high
T1CK[2:0]]
Input clock selection
00 : fXI 10 : fXI
8
÷
01 : fXI 211 : using the Timer 0 clock
÷
16BIT
16-bit mode selection
0 : 8-bit mode
1 : 16-bit mode
T1CN
T1ST
Continue control bit
0 : Stop counting
1 : Start counting continuously
PWM1E
CAP1
PWM enable bit
0 : Disables PWM
1 : Enables PWM
Start control bit
0 : Stop counting
1 : Counter register is cleared and start again
Capture mode selection bit.
0 : Disables Capture
1 : Enables Capture
Figure 15-1 Timer Mode Register ( TMx , x = 0~1 )
Nov. 1999 Ver 0.0
preliminary
51
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