ST16C552 Exar Corporation, ST16C552 Datasheet - Page 3

• Manufacturer Part Number: ST16C552
• Description: DUAL UART WITH 16-BYTE FIFO AND PARALLEL PRINTER PORT
• Manufacturer: Exar Corporation

SYMBOL DESCRIPTION
A0
A1
A2
-ACK
-AutoFDXT
BIDEN
BUSY
CLK
-CSA
-CSB
-CSP
D0-D7
Symbol
Rev. 3.40
14-21
Pin
35
34
33
68
56
66
32
38
1
4
3
Signal Type
I/O
I/O
I
I
I
I
I
I
I
I
I
I
Address-0 Select Bit - Internal registers address selection.
Address-1 Select Bit - Internal registers address selection.
Address-2 Select Bit - Internal registers address selection.
Acknowledge (with internal pull-up) - General purpose input
or line printer acknowledge (active low). a logic 0 from the
printer, indicates successful data transfer to the print buffer.
General purpose I/O (open drain, with internal pull-up) or
automatic line feed (open drain input with internal pull-up).
When this signal is low the printer should automatically line
feed after each line is printed.
Bi-Direction Enable - PD7-PD0 direction select. A logic 0
sets the parallel port for I/O Select Register Control. A logic
1 sets the parallel port for Control Register Bit-5 Control.
Busy (with internal pull-up) - General purpose input or line
printer busy (active high). can be used as an output from the
printer to indicate printer is not ready to accept data.
Clock Input. - An external clock must be connected to this
pin to clock the baud rate generator and internal circuitry
(see Programmable Baud Rate Generator). This input is not
5V tolerant.
Chip Select A - A logic 0 at this pin enables the serial
channel-A UART registers for CPU data transfers.
Chip Select B - A logic 0 at this pin enables the serial
channel-B UART registers for CPU data transfers.
Printer Port Chip Select - (active low). A logic 0 at this pin
enables the parallel printer port registers and/or PD7-PD0
for external CPU data transfers.
Data Bus (Bi-directional) - These pins are the eight bit, three
state data bus for transferring information to or from the
controlling CPU. D0 is the least significant bit and the first
data bit in a transmit or receive serial data stream.
3
Pin Description
ST16C552/552A