5. Counter/Timers
42
Status Register
Each counter/timer has a Status register. The Status register must be read using the
multiple latch command specified in the Control register.
7
6
5
4
3
2
1
0
Register: Status
Address: 40h + Channel
Count Format
BCD
Access: Write
Access
0 Binary
Mode
1 BCD
Operating Mode
000 Terminal count interrupt (Mode 0)
001 Retriggerable one-shot (Mode 1)
010 Rate generator (Mode 2)
011 Square wave generator (Mode 3)
100 Software strobe (Mode 4)
101 Hardware strobe (Mode 5)
110 Same as "010"
111 Same as "011"
Access Mode
00 Count latch command
01 Low byte only
10 High byte only
11 Low byte followed by high byte
NULCNT
OUTPUT
Count Status
Output Status
0 latest count written to the counter was loaded
1 a count was written to the counter but not yet loaded
0 OUT
n
is low
1 OUT
n
is high
Status Register