SAB80515 Datasheet, PDF (67/270 Pages) Siemens Semiconductor Group – 8-Bit Single-Chip Microcontroller Family

On-Chip Peripheral Components
Figure 7-20
Special Function Register TMOD (Address 89H)
89H GATE C/T M1 M0
Timer 1
Timer/counter 0/1 mode control register.
GATE
C/T M1
Timer 0
M0 TMOD
Bit
Symbol
Gate
Gating control.
When set, timer/counter "x" is enabled only while "INTx" pin is high and
"TRx" control bit is set.
When cleared timer "x" is enabled whenever "TRx" control bit is set.
C/T
Counter or timer select bit.
Set for counter operation (input from "Tx" input pin).
Cleared for timer operation (input from internal system clock).
M1
M0
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. TH00 is an 8-bit timer only controlled by timer 1 control bits.
1
1 Timer 1:
Timer/counter 1 stops
Semiconductor Group
67