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Special Function Register TMOD (Address 89 H )
Bit No.
MSB
7
89 H
Gate
Bit
Function
GATE
Timer 1/0 gating control
When set, timer/counter "x" is enabled only while "INT x" pin is high and "TRx"
control bit is set.
When cleared timer "x" is enabled whenever "TRx" control bit is set.
C/T
Timer 1/0 counter or timer select bit
Set for counter operation (input from "Tx" input pin).
Cleared for timer operation (input from internal system clock).
M1
Timer 1/0 mode select bits
M0
M1
0
0
1
1
Semiconductor Group
6
5
4
C/T
M1
M0
Timer 1 Control
M0
Function
0
8-bit timer/counter:
"THx" operates as 8-bit timer/counter
"TLx" serves as 5-bit prescaler
1
16-bit timer/counter.
"THx" and "TLx" are cascaded; there is no prescaler
0
8-bit auto-reload timer/counter.
"THx" holds a value which is to be reloaded into "TLx" each
time it overflows
1
Timer 0 :
TL0 is an 8-bit timer/counter controlled by the standard
timer 0 control bits. TH0 is an 8-bit timer only controlled by
timer 1 control bits.
Timer 1 :
Timer/counter 1 stops
On-Chip Peripheral Components
3
2
Gate
C/T
Timer 0 Control
6-18
C541U
Reset Value : 00 H
LSB
1
0
M1
M0
TMOD
1999-04-01
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