Rainbow Electronics T89C5121 - Manual (Page 79)

79
A/T8xC5121
4164G–SCR–07/06
Reset Value = 0000 0000b
Table 56. TMOD Register
TMOD (S:89h) - Timer 0/Counter Mode Control Registers
7 6 5 4 3 2 1 0
GATE1 C/T1# M11 M01 GATE0 C/T0# M10 M00
Bit Number Bit Mnemonic Description
7 GATE1
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.
6 C/T1#
Timer 1 Counter/Timer 0 Select bit
Clear for Timer 0 operation: Timer 1 counts the divided-down system clock.
Set for Counter operation: Timer 1 counts negative transitions on external pin T1.
5 M11 Timer 1 Mode Select bits
M11
M01 Operating mode
0 0 Mode 0:8-bit Timer 0/Counter (TH1) with 5-bit prescaler (TL1).
0 1 Mode 1:16-bit Timer 0/Counter.
1 0 Mode 2:8-bit auto-reload Timer 0/Counter (TL1). Reloaded from TH1 at overflow.
1 1 Mode 3:Timer 1 halted. Retains count.
4 M01
3 GATE0
Timer 0 Gating Control bit
Clear to enable Timer 0 whenever TR0 bit is set.
Set to enable Timer 0/Counter 0 only while INT0 pin is high and TR0 bit is set.
2 C/T0#
Timer 0 Counter/Timer 0 Select bit
Clear for Timer 0 operation: Timer 0 counts the divided-down system clock.
Set for Counter operation: Timer 0 counts negative transitions on external pin T0.
1 M10 Timer 0 Mode Select bit
M10 M00 Operating mode
0
0 Mode 0:8-bit Timer 0/Counter (TH0) with 5-bit prescaler (TL0).
0 1 Mode 1:16-bit Timer 0/Counter
1 0 Mode 2:8-bit auto-reload Timer 0/Counter (TL0). Reloaded from TH0 at overflow.
1 1 Mode 3:TL0 is an 8-bit Timer 0/Counter.
TH0 is an 8-bit Timer 0 using Timer 1’s TR0 and TF0 bits.
0 M00