1997 Dec 15
24
Philips Semiconductors
Product specication
8-bit microcontrollers
P83C524; P80C528; P83C528
11.1.1
TIMER/COUNTER MODE CONTROL REGISTER (TMOD)
Table 4
Timer/Counter Mode Control register (address 89H)
Table 5
Description of the TMOD bits
Table 6
TMOD M1 and M0 operating modes
76543210
TIMER 1
TIMER 0
GATE
C/TM1
M0
GATE
C/TM1
M0
BIT
SYMBOL
FUNCTION
TIMER 1
7GATE
Timer 1 gating control: when set, Timer/counter '1' is enabled only while 'INT1' pin is
HIGH and 'TR1' control bit is set. When cleared, Timer/counter '1' is enabled whenever
'TR1' control bit is set.
6C/T
Timer or counter selector: cleared for timer operation (input from internal system
clock). Set for counter operation (input from 'T1' input pin).
5M1
operating mode: see Table 6.
4M0
operating mode: see Table 6.
TIMER 0
3GATE
Timer 0 gating control: when set, Timer/counter '0' is enabled only while 'INT0' pin is
HIGH and 'TR0' control bit is set. When cleared, Timer/counter '0' is enabled whenever
'TR0' control bit is set.
2C/T
Timer or counter selector: cleared for timer operation (input from internal system
clock). Set for counter operation (input from 'T0' input pin).
1M1
operating mode: see Table 6.
0M0
operating mode: see Table 6.
M1
M0
FUNCTION
00
8-bit timer/counter: 'THx' with 5-bit prescaler.
01
16-bit timer/counter: 'THx' and 'TLx' are cascaded, there is no prescaler.
10
8-bit autoload timer/counter: 'THx' holds a value which is to be reloaded into 'TLx'
each time it overows.
11
Timer 0: TL0 is an 8-bit timer/counter controlled by the standard Timer 0 control bits.
TH0 is an 8-bit timer controlled by Timer 1 control bits.
11
Timer 1: Timer/counter 1 stopped.