AT89C5132
Bit
Bit
Number Mnemonic Description
Timer 1 Gating Control Bit
Clear to enable Timer 1 whenever TR1 bit is set.
Set to enable Timer 1 only while INT1 pin is high and TR1 bit is set.
7
GATE1
Timer 1 Counter/Timer Select Bit
6
5
C/T1#
M11
Clear for Timer operation: Timer 1 counts the divided-down system clock.
Set for Counter operation: Timer 1 counts negative transitions on external pin T1.
Timer 1 Mode Select Bits
M11 M01
Operating mode
0
0
1
0
1
0
Mode 0: 8-bit Timer/Counter (TH1) with 5-bit prescaler (TL1).
Mode 1: 16-bit Timer/Counter.
4
3
M01
Mode 2: 8-bit auto-reload Timer/Counter (TL1).(1)
1
1
Mode 3: Timer 1 halted. Retains count.
Timer 0 Gating Control Bit
GATE0
Clear to enable Timer 0 whenever TR0 bit is set.
Set to enable Timer/Counter 0 only while INT0 pin is high and TR0 bit is set.
Timer 0 Counter/Timer Select Bit
Clear for Timer operation: Timer 0 counts the divided-down system clock.
Set for Counter operation: Timer 0 counts negative transitions on external pin T0.
2
1
C/T0#
M10
Timer 0 Mode Select Bit
M10 M00
Operating mode
Mode 0: 8-bit Timer/Counter (TH0) with 5-bit prescaler (TL0).
0
0
1
0
1
0
Mode 1: 16-bit Timer/Counter.
Mode 2: 8-bit auto-reload Timer/Counter (TL0).(2)
M00
0
1
1
Mode 3: TL0 is an 8-bit Timer/Counter.
TH0 is an 8-bit Timer using Timer 1’s TR0 and TF0 Bits.
Reset Value = 0000 0000b
Notes: 1. Reloaded from TH1 at overflow.
2. Reloaded from TH0 at overflow.
Table 42. TH0 Register
TH0 (S:8Ch) – Timer 0 High Byte Register
7
-
6
-
5
-
4
-
3
-
2
-
1
-
0
-
Bit
Bit Number Mnemonic Description
7:0 High Byte of Timer 0
Reset Value = 0000 0000b
55
4173E–USB–09/07
ATMEL [ ATMEL ]
