SDLC COMMUNICATIONS CONTROLLER
As of Production Version P03
28 August 2007
The table below describes the I/O characteristics for each signal on the IC. The signal names
correspond to the signal names on the pinout diagrams provided. The table below provides the I/O
description of the IA8044 and the IA8344.
P0.7 – P0.0
P1.7 – P1.0
P2.7 – P2.0
P3.7 – P3.0
Reset. This pin when held high for two machine cycles while
the oscillator is running will cause the chip to reset.
Address Latch Enable. Used to latch the address on the falling
edge for external memory accesses.
Program Store Enable. When low acts as an output enable for
external program memory.
External Access. When held low EA will cause the
IA8044/IA8344 to fetch instructions from external memory.
Port 0. 8 bit I/O port and low order multiplexed address/data
byte for external accesses.
Port 1. 8-bit I/O port. Two bits have alternate functions, P1.6
(RTS) and P1.7 (CTS).
Port 2. 8-bit I/O port. It also functions as the high order
address byte during external accesses.
Port 3. 8-bit I/O port. Port 3 bits also have alternate functions
as described below.
P3.0 – RXD. Receive data input for SIU or direction control
for P3.1 dependent upon datalink configuration.
P3.1 – TXD. Transmit data output for SIU or data
input/output dependent upon datalink configuration. Also
enables diagnostic mode when cleared.
P3.2 – INT0. Interrupt 0 input or gate control input for
P3.3 – INT1. Interrupt 1 input or gate control input for
P3.4 – T0. Input to counter 0.
P3.5 – SCLK/T1. SCLK input to SIU or input to counter 1.
P3.6 – WR. External memory write signal.
P3.7 – RD. External memory read signal.
Crystal Input 1. Connect to VSS when external clock is used on
XTAL2. May be connected to a crystal (with XTAL2), or may
be driven directly with a clock source (XTAL2 not connected).
Crystal Input 2. May be connected to a crystal (with XTAL1),
or may be driven directly with an inverted clock source (XTAL1
tied to ground).
Copyright © 2007
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