Notes
79RC32438 User Reference Manual
12 - 1
November 4, 2002
Chapter 12
General Purpose I/O
Controller
Introduction
This chapter describes the operation of the General Purpose I/O (GPIO) Controller and the operation of
the general purpose I/O pins. This chapter also describes how the GPIO Controller and pins are configured
to operate as a general purpose I/O or as an alternate function.
Functional Overview
The general purpose I/O controller provides 32 general purpose I/O pins which may be individually
configured as:
General purpose input
General purpose output
Alternate functions
When configured as general purpose input, each pin can be used as an active high or active low level
interrupt input.
As shown in Table 12.1, each general purpose I/O (GPIO) bit is shared with another on-chip function.
The GPIO function (GPIOFUNC) field in the general purpose I/O function (GPIOFUNC) register controls
whether a GPIO bit operates as a general purpose I/O or as the specified alternate function.
GPIO
Pin
Alternate
Function
Pin Name
Alternate Function Description
Alternate
Function
Pin Type
0
U0SOUT
UART channel 0 serial output (see Chapter 13)
Output
1
U0SINP
UART channel 0 serial input (see Chapter 13)
Input
2
U0RIN
UART channel 0 ring indicator (see Chapter 13)
Input
3
U0DCDN
UART channel 0 data carrier detect (see Chapter 13)
Input
4
U0DTRN
UART channel 0 data terminal ready (see Chapter 13)
Output
5
U0DSRN
UART channel 0 data set ready (see Chapter 13)
Input
6
U0RTSN
UART channel 0 request to send (see Chapter 13)
Output
7
U0CTSN
UART channel 0 clear to send (see Chapter 13)
Input
8
U1SOUT
UART channel 1 serial output (see Chapter 13)
Output
9
U1SINP
UART channel 1 serial input (see Chapter 13)
Input
10
U1DTRN
UART channel 1 data terminal ready (see Chapter 13)
Output
11
U1DSRN
UART channel 1 data set ready (see Chapter 13)
Input
12
U1RTSN
UART channel 1 request to send (see Chapter 13)
Output
13
U1CTSN
UART channel 1 clear to send (see Chapter 13)
Input
14
DMAREQN0
External DMA channel 0 request (see Chapter 9)
Input
15
DMAREQN1
External DMA channel 1 request (see Chapter 9)
Input
Table 12.1 General Purpose I/O Pin Alternate Function (Part 1 of 2)