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¡ Semiconductor
Special Function Registers
Timer mode register (TMOD)
NAME
ADDRESS
TMOD
89H
BIT LOCATION
FLAG
TMOD.0
M0
TMOD.1
M1
TMOD.2
C/T
TMOD.3
GATE
TMOD.4
M0
TMOD.5
M1
TMOD.6
C/T
TMOD.7
GATE
MSB
7
6
5
GATE
C/T
M1
M1
M0
Timer/counter 0 mode setting
0
0
8-bit timer/counter with 5-bit prescalar.
0
1
16-bit timer/counter.
1
0
8-bit timer/counter with 8-bit auto reloading.
1
1
Timer/counter 0 separated into TLO (8-bit) timer/counter
and TH0 (8-bit) timer/counter. TF0 is set by TL0 carry, and
TF1 is set by TH0 carry.
Timer/counter 0 count clock designation control bit.
XTAL1•2 divided by 12 clocks is the input applied to timer/counter 0 when
C/T = "0".
The external clock applied to the T0 pin is the input applied to timer/counter 0
when C/T = "1".
When this bit is "0", the TR0 bit of TCON (timer control register) is used to
control the start and stop of timer/counter 0 counting.
If this bit is "1", timer/counter 0 starts counting when both the TR0 bit of TCON
and INT0 pin input signal are "1", and stops counting when either is changed
to "0".
M1
M0
Timer/counter 1 mode setting
0
0
8-bit timer/counter with 5-bit prescalar.
0
1
16-bit timer/counter
1
0
8-bit timer/counter with 8-bit auto reloading.
1
1
Timer/counter 1 operation stopped.
Timer/counter 1 count clock designation control bit.
XTAL1•2 divided by 12 clocks is the input applied to timer/counter 1 when
C/T = "0".
The external clock applied to the T1 pin is the input applied to timer/counter 1
when C/T = "1".
When this bit is "0", the TR1 bit of TCON is used to control the start and stop of
timer/counter 1 counting.
If this bit is "1", timer/counter 1 starts counting when both the TR1 bit of TCON
and INT1 pin input signal are "1", and stops counting when either is changed
to "0".
MSM80C154S/83C154S
4
3
2
M0
GATE
C/T
FUNCTION
LSB
1
0
M1
M0
269
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