25
ST16C552/552A
Rev. 3.40
source driver and internal pull-up so that it may be wire-
or’d with other outputs. COM bit-1 is used to read status
while CON bit 1 is used to set an output state. If it is to
function as an input, CON bit-1 shall be set to a logic 1
first.
Logic 0 = -STROBE pin is a logic 1. (normal default
condition)
Logic 1 = -STROBE pin is a logic 0.
COM BIT-1:
-AutoFDXT is a bi-directional signal with an open
source driver and internal pull-up so that it may be
wire-or’d with other outputs. COM bit-1 is used to read
status while CON bit 1 is used to set an output state.
If it is to function as an input, CON bit-1 shall be set to
a logic 1 first.
Logic 0 = -AutoFDXT pin is a logic 1. (normal default
condition)
1= -AutoFDXT pin is a logic 0.
COM BIT-2:
INIT is a bi-directional signal with an open source
driver and internal pull-up so that it may be wire-or’d
with other outputs. COM bit-2 is used to read status
while CON bit 2 is used to set an output state. If it is to
function as an input, CON bit-1 shall be set to a logic
1 first.
Logic 0 = INIT pin is a logic 0. (normal default
condition)
Logic 1 = INIT pin is a logic 1.
COM BIT-3:
-SLCTIN is a bi-directional signal with an open source
driver and internal pull-up so that it may be wire-or’d
with other outputs. COM bit-1 is used to read status
while CON bit 1 is used to set an output state. If it is to
function as an input, CON bit-1 shall be set to a logic
1 first.
Logic 0 = -SLCTIN pin is a logic 1 (normal default
condition)
Logic 1 = -SLCTIN pin is a logic 0
COM BIT-4:
This bit allows the state of -INTP to be read back by the
external CPU.
Logic 0 = Interrupt (-INTP output) is disabled (normal
default condition)
Logic 1 = Interrupt (-INTP output) is enabled
COM BIT 5-7:
Not Used - initialized to a logic 1.
Control Register (CON)
This register provides control of the printer port output
logical states and controls the printer interrupts INIT
and -INTP. With the exception of PD 0-7 IN/OUT, the
status of this register may be read by reading the COM
register.
CON BIT-0:
The -STROBE output control bit is under software
control, i.e., the hardware will not generate a strobe. It
is up to software to return the state of -STROBE to the
inactive (logic 1) state. The hardware driver is open
drain so that -STROBE may be wire-or’d. The state of
this bit can be read using COM bit-0.
Logic 0 = -STROBE output is set to a logic 1. (normal
default condition)
Logic 1 = -STROBE output is set to a logic 0.
CON BIT-1:
The -AutoFDXT output control bit is set by software
using CON bit-1. The hardware driver is open drain so
that -AutoFDXT may be wire-or’d. The state of this bit
can be read using COM bit-1.
Logic 0 = -AutoFDXT output is set to a logic 1. (normal
default condition)
Logic 1 = -AutoFDXT output is set to a logic 0.
CON BIT-2:
The INIT output control bit is set by software using
CON bit-2. The hardware driver is open drain so that
INIT may be wire-or’d. The state of this bit can be read
using COM bit-2.
Logic 0 = INIT output is set to a logic 0. (normal default
condition)
Logic 1 = INIT output is set to a logic 1.
CON BIT-3:
The -SLCTIN output control bit is set by software using
CON bit-3. The hardware driver is open drain so that
-AutoFDXT may be wire-or’d. The state of this bit can
be read using COM bit-3.
