User Manual

 39
Programming Considerations
GPIO Pin Use
GPIO Pin Use
Name
Register
Bit
Category
External
Interface
Description
TXD/
GPIO-6
PORTA7 Allocated
Pin 4 on the
main header
Used for port 1 serial transmit but
can be reassigned as GPIO input
or output. If used with the
development board, this pin maps
to GPIO-6.
DTR/
GPIO-5
PORTA6 Allocated
Pin 6 on the
main header
Used for the port 1 serial DTR
signal but can be reassigned as
GPIO input or output. If used
with the development board, this
pin maps to GPIO-5.
See the
description
PORTA5,
PORTA4
Allocated
Pin 5 on the
main header
Since these two processor pins
map to the same header pin, one
must
be configured as an input to
avoid contention. Under normal
serial conditions, PORTA5 is
configured to deliver the port 1
RTS signal and PORTA4 for
GPIO input. To use the port for
SPI, configure PORTA5 for
GPIO input and PORTA4 to
deliver SPI clock.
When used with the development
board, header pin 5 maps to
GPIO-4.
RXD/
GPIO-7
PORTA3 Allocated
Pin 3 on the
main header
Used for port 1 serial receive but
can be reassigned as GPIO input
or output. If used with the
development board, this pin maps
to GPIO-7.