|
Commodore |
, . .commodore
~ aamiconduct:ar group
~~@~
MPS
6551
ASSYNCH RONOUS
COMMUNICATION
INTERFACE
ADAPTER
[ 6551 ASYNCHRONOUS COMMUNICATION INTERFACE ADAPTER
CONCEPT:
The 6551 is an Asynchronous Communication Adapter (ACIA) intended to provide for interfacing the 6500/6800
microprocessor families to serial communication data sets and modems. A unique feature is the inclusion of an
on-chip programmable baud rate generator, with a crystal being the only external com pone t required.
FEATURES:
• On-chip baud rate generator: 15 programmable baud
rates derived from a standard 1.8432 M Hz external
crystal (50 to 19,200 baud).
• Programmable interrupt and status register to simplify
software design.
• Single +5 volt power supply.
• Serial echo mode.
• False start bit detection.
• 8-bit bi-directional data bus for direct communicati~
)
-standard baud rates (up
engths; number of stop bits; and
nd detection.
control signals provided.
:¥ep';' none, mark, space).
r half-duplex operation.
9 bit transmission.
ORDER NUMBER
MXS 6551
PACKAGE DESIGNATOR
C = CERAMIC
P = PLASTIC
6551 PIN CONFIGURATION
GND 1
2
3
4
5
6
7
RTS 8
CTS 9
TxD 10
l5'i'R 11
RxD 12
RSO 13
RS1 14
28 R/W
27 ~2
26 iRa
25 DB7
24 DB6
23 DB5
22 DB4
21 DB3
20 DB2
19 DB1
18 DBO
17 DSR
16 DCD
15 Vce
2-129
Figure 1. Block Diagram
MPS
6551
132
R;W
CSo
CS1
RSO
RS1
RES
SELECT
AND
CONTROL
LOGIC
DATA
BUS
BUFFERS
TRANSMIT
CONTROL
CTS
TRANSMIT
DATA
REGISTER
STATUS
REGISTER
CONTROL
REGISTER
RECEIVE
DATA
REGISTER
TRANSMIT
SHIFT
REGISTER
TxD
INTERRUPT
LOGIC
fRO
OCD
i5SR
BAUD
RATE
GENERATOR
RxC
XTAL 1
XTAL2
RECEIVE
SHIFT
REGISTER
RxD
COMMAND
REGISTER
RECEIVE
CONTROL
L------------__ DiR
L-------------__________~_Rf:S
2-130
|