Application NoteNxp

Building a USB/IIC/SPI Bridge with ColdFire OTG Module

Guide for implementing a USB-to-I2C/SPI bridge using Freescale MCF522xx ColdFire MCUs to interface a Windows PC with external EEPROM memories.

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Overview

This application note provides a technical reference for using the USB On-The-Go (OTG) module of Freescale MCF522xx ColdFire microcontrollers as a communication bridge. The design enables a PC running Windows to read and write to I2C and SPI EEPROMs, specifically the Atmel AT24C02B and AT25020A. It details the configuration of the CMX USB stack, customized USB data packets, and device descriptors. The document covers firmware development in CodeWarrior, interrupt priority management for USB, SPI, and IIC modules, and the creation of a PC-side host application using Visual Studio and the Microsoft USB Host API.

Use Cases

Interfacing a PC with I2C or SPI peripherals via USB
Programming external EEPROM memories from a computer
Developing custom USB device classes for industrial communication
Prototyping USB-to-serial protocol converters

Topics

MCF52221

ColdFire

USB bridge

I2C

SPI

EEPROM

OTG module

CMX USB stack

AT24C02B

AT25020A

CodeWarrior

Referenced Parts

MCF52221

Freescale Semiconductor

flash object image for the MCF52221.

AT24C02B

Atmel

Serial EEPROM AT24C02B (IIC protocol)

AT25020A

Atmel

Serial EEPROM AT24C02B (IIC protocol) and an AT25020A (SPI protocol).

x86

NXP

• Bulkusb.sys was built using WinXP x86 Free Build Environment command line found on

MCF52221	Freescale Semiconductor	flash object image for the MCF52221.
AT24C02B	Atmel	Serial EEPROM AT24C02B (IIC protocol)
AT25020A	Atmel	Serial EEPROM AT24C02B (IIC protocol) and an AT25020A (SPI protocol).
x86	NXP	• Bulkusb.sys was built using WinXP x86 Free Build Environment command line found on