IMP16C552-CJ68 IMP Inc, IMP16C552-CJ68 Datasheet - Page 21

• Manufacturer Part Number: IMP16C552-CJ68
• Description: Dual Universal Asynchronous Receiver/Transmitter (UART) with 16-BYTE FIFO & Parallel Printer Port
• Manufacturer: IMP Inc

21
Parallel Port Description
The parallel port supports Centronics type printers. When CS2* is low, the parallel port is selected allowing access to all
parallel port data, control and status registers.
PARALLEL PORT REGISTER ADDRESSES
Cs2*
0
0
0
0
0
0
0
0
ACCESSIBLE PARALLEL PORT REGISTERS
Bit
No
.
0
1
2
3
4
5
6
7
Register Description
Port Data Register
This 8-bit data register can be modified by the
CPU to write data to the parallel port.
Bits 0-7: Data bits
Port Status Register
This register is a read only register reporting
the state of status input pins ERROR*, SLCT,
PE, ACK*, and BUSY.
Port
Data
Register
Data Bit 0
Data Bit 1
Data Bit 2
Data Bit 3
Data Bit 4
Data Bit 5
Data Bit 6
Data Bit 7
A1
0
0
1
1
0
0
1
1
A0
0
1
0
1
0
1
0
1
Port
Status
Register
(Read
only)
1
1
1
ERRORS*
SLCTS
PES
ACKS*
BUSYS*
IOR*
0
0
0
0
1
1
1
1
LOW*
1
1
1
1
0
0
0
0
Port
Control
Registe
r
STBE
AFDE
INITE*
SLINE
INTE
1
1
1
408-432-9100/www.impweb.com
Operation
Read Port Data Register
Read Port Status Register
Read Port Control Register
Invalid Operation
Write Port Data Register
Invalid Operation
Write Port Control Register
Invalid Operation
Bits 0:2: these bits are always read as 1.
Bits 3: Reports status of ERROR* pin.
Bits 4: Reports status of SLCT pin.
Bits 5: Reports status of PE pin.
Bits 6: Reports status of ACK*.
Bits 7: Reports inverted status of BUSY pin.
Port Control Register
This register controls
AFD*, INIT*, SLIN*, INT2, When read, it
reports the status of the control pins.
Bits 0: This bit, when written 1/0, force STB*
pin low/high.
Bits 1: This bit, when written 1/0, force AFD*
pin low/high.
Bits 2: This bit, when written 1/0, force INIT*
pin low/high.
Bits 3: This bit, when written 1/0, force SLIN*
pin low/high.
Bits 4: This bit, when written 1/0, enables /
disables INT2 pin.
Bits 5-7: Always read as 1.
IMP16C552
IMP16C552
output pins STB*,
© 2002 IMP, Inc.