The 8051 Microcontroller and Embedded

Department of Computer Scien

ce and Information Engineering

National Cheng Kung University, TAIWAN

HANEL

PROGRAMMING

TIMERSTMODRegister(cont’)

Split timer mode

3

(^11)
8-bit auto reload8-bit auto reload timer/counter; THx holds a value which is to be reloaded TLx each time it overfolws
2
(^01)
16-bit timer mode16-bit timer/counter THx and TLx are cascaded; there is no prescaler
1
(^10)
13-bit timer mode8-bit timer/counter THx with TLx as 5-bit prescaler
0
(^00)
Operating Mode
Mode
M0M1
Timer1
GATE
C/T
M1
M0
(MSB)
Timer0
GATE
C/T
M1
(LSB)M0
Timer or counter selectedCleared for timer operation (input from internal system clock)Set for counter operation (input from Tx input pin)
Gating control when set. Timer/counter is enable only while the INTx pin is high and the TRx control pin is setWhen cleared,
the timer is
enabled whenever the TRxcontrol bit is set