82C54 Datasheet, PDF (2/18 Pages) Intel Corporation – CHMOS PROGRAMMABLE INTERVAL TIMER

82C54
Symbol
D₇-D₀
CLK 0
OUT 0
GATE 0
GND
OUT 1
GATE 1
CLK 1
GATE 2
OUT 2
CLK 2
A₁ A₀
CS
RD
WR
V_CC
NC
Pin Number
DIP
PLCC
1-8
2-9
9
10
11
12
13
14
15
16
17
18
20-19
10
12
13
14
16
17
18
19
20
21
23-22
21
24
22
26
23
27
24
28
1 11 15 25
Table 1 Pin Description
Type
Function
IO
Data Bidirectional tri-state data bus lines
connected to system data bus
I
Clock 0 Clock input of Counter 0
O
Output 0 Output of Counter 0
I
Gate 0 Gate input of Counter 0
Ground Power supply connection
O
Out 1 Output of Counter 1
I
Gate 1 Gate input of Counter 1
I
Clock 1 Clock input of Counter 1
I
Gate 2 Gate input of Counter 2
O
Out 2 Output of Counter 2
I
Clock 2 Clock input of Counter 2
I
Address Used to select one of the three Counters
or the Control Word Register for read or write
operations Normally connected to the system
address bus
A₁
A₀
Selects
0
0
Counter 0
0
1
Counter 1
1
0
Counter 2
1
1
Control Word Register
I
Chip Select A low on this input enables the 82C54
to respond to RD and WR signals RD and WR are
ignored otherwise
I
Read Control This input is low during CPU read
operations
I
Write Control This input is low during CPU write
operations
Power ^a5V power supply connection
No Connect
FUNCTIONAL DESCRIPTION
General
The 82C54 is a programmable interval timer counter
designed for use with Intel microcomputer systems
It is a general purpose multi-timing element that can
be treated as an array of I O ports in the system
software
The 82C54 solves one of the most common prob-
lems in any microcomputer system the generation
of accurate time delays under software control In-
stead of setting up timing loops in software the pro-
grammer configures the 82C54 to match his require-
ments and programs one of the counters for the de-
sired delay After the desired delay the 82C54 will
interrupt the CPU Software overhead is minimal and
variable length delays can easily be accommodated
Some of the other counter timer functions common
to microcomputers which can be implemented with
the 82C54 are
 Real time clock
 Even counter
 Digital one-shot
 Programmable rate generator
 Square wave generator
 Binary rate multiplier
 Complex waveform generator
 Complex motor controller
2