C517A_99 Datasheet, PDF (83/218 Pages) Siemens Semiconductor Group – 8-Bit CMOS Microcontroller

On-Chip Peripheral Components
C517A
Special Function Register TMOD (Address 89H)
Reset Value : 00H
Bit No. MSB
LSB
7
6
5
4
3
2
1
0
89H Gate C/T M1 M0 Gate C/T M1 M0 TMOD
Timer 1 Control
Timer 0 Control
Bit
GATE
C/T
M1
M0
Function
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.
Counter or timer select bit
Set for counter operation (input from "Tx" input pin).
Cleared for timer operation (input from internal system clock).
Mode select bits
M1
M0
Function
0
0
8-bit timer/counter:
"THx" operates as 8-bit timer/counter
"TLx" serves as 5-bit prescaler
0
1
16-bit timer/counter.
"THx" and "TLx" are cascaded; there is no prescaler
1
0
8-bit auto-reload timer/counter.
"THx" holds a value which is to be reloaded into "TLx" each
time it overflows
1
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
Semiconductor Group
6-17