Freescale Semiconductor
10-1
MCF51CN128 Reference Manual, Rev. 6
Chapter 10
Rapid GPIO (RGPIO)
10.1
Introduction
The Rapid GPIO (RGPIO) module provides a 16-bit general-purpose I/O module directly connected to the
processor’s high-speed 32-bit local bus. This connection plus support for single-cycle, zero wait-state data
transfers allows the RGPIO module to provide improved pin performance when compared to more
traditional GPIO modules located on the internal slave peripheral bus.
Many of the pins associated with a device may be used for several different functions. Their primary
functions are to provide external interfaces to access off-chip resources. When not used for their primary
function, many of the pins may be used as general-purpose digital I/O (GPIO) pins. The definition of the
exact pin functions and the affected signals is specific to each device. Every GPIO port, including the
RGPIO module, has registers that configure, monitor, and control the port pins.
NOTE
•
Use pin mux control registers from
Section 2.3, “Pin Mux Controls
” to
assign RGPIO signals to the MCF51CN128 package pins.
•
Most pin functions default to GPIO and must be software configured
before using RGPIO.
10.1.1
Overview
The RGPIO module provides 16-bits of high-speed GPIO functionality, mapped to the processor’s bus.
The key features of this module include:
•
16 bits of high-speed GPIO functionality connected to the processor’s local 32-bit bus
•
Memory-mapped device connected to the ColdFire core’s local bus
— Support for all access sizes: byte, word, and longword
— All reads and writes complete in a single data phase cycle for zero wait-state response
•
Data bits can be accessed directly or via alternate addresses to provide set, clear, and toggle
functions
— Alternate addresses allow set, clear, toggle functions using simple store operations without the
need for read-modify-write references
•
Unique data direction and pin enable control registers
•
Package pin toggle rates typically 1.5–3.5x faster than comparable pin mapped onto peripheral bus
