ST16C452CJ68PS-F Datasheet, PDF (5/30 Pages) Exar Corporation – DUAL UART WITH PARALLEL PRINTER PORT

ST16C452/452PS
SYMBOL DESCRIPTION
Symbol
-IOW
PD7-PD0
PE
RDOUT
-RESET
N.C.
SLCT
-SLCTIN
Rev. 3.20
Pin
36
46-53
67
44
39
9,61
65
58
Signal Type
Pin Description
for either UART channels A/B or A0-A1 for the printer port,
onto D0-D7 data bus for a read cycle by an external CPU.
I
Write strobe.- A logic 0 transition on this pin will transfer the
data on the internal data bus (D0-D7), as defined by either
address bits A0-A2 for UART channels A/B or A0-A1 for the
printer port, into an internal register during a write cycle from
an external CPU.
I/O
Printer Data port (Bi-directional three state) - These pins are
the eight bit, three state data bus for transferring information
to or from an external device (usually a printer). D0 is the
least significant bit. PD7-PD0 are latched during a write
cycle (output mode).
I
Paper Empty - General purpose input or line printer paper
empty (Internal pull-up). This pin can be connected to
provide a printer out of paper indication.
O
Read Out (active high) - This pin goes to a logic 1 when the
external CPU is reading data from the 452/452PS. This
signal can be used to enable/disable external transceivers
or other logic functions.
I
Master Reset (active low) - a logic 0 on this pin will reset the
internal registers and all the outputs. The UART transmitter
output and the receiver input will be disabled during reset
time. (See ST16C452/452PS External Reset Conditions for
initialization details.)
Not Used. Should be left open.
I
Select (with internal pull-up) - General purpose input or line
printer select status. Normally this pin is connected to a
printer output (active low) that indicates the ready status of
a printer, i.e., on-line and/or on-line and ready.
I/O
Select In (open drain, with internal pull-up) - General
purpose I/O or line printer select. This pin can be read via
Bit-3 in the printer command register, or written via bit-3 in
the printer control register. As this pin is open-drain, it can be
wire-or’d with other outputs. Normally this signal is connected
5