MCF5272 Просмотр технического описания (PDF) - Oxford Semiconductor

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MCF5272

Interfacing OTG243 USB Host/Function/OTG Controller to MCF5272 ColdFire Processor

Oxford Semiconductor 

TransDimension Inc.

Interfacing OTG243 to Motorola MCF5272 ColdFire Processor

2. Bus Interface

2.1 Recommendations

For the MCF5272, we recommend that:

ƒ The OTG243 is interfaced directly to MCF5272’s system bus.

ƒ The OTG243 operates in 16-bit mode (pin /EXVBO pulled-down). This reference design has

been tested in 16-bit mode, but should work just as well in 32-bit mode.

ƒ The OTG243 is accessed through the MCF5272 chip-select as memory-mapped peripheral.

Any of the chip-select signals nCS[5:2] can be programmed for an address location, with

masking capabilities, port size, burst capability indication, and wait-state generation.

nCS2 is used for this reference design.

ƒ The chosen chip-select is programmed to 16-bit access with a bus cycle compatible to that of

the OTG243’s.

The above recommendations are assumed throughout this document. Alternative interfacing

schemes, such as 32-bit access to the OTG243, can function just as well.

2.2 Required Procedure

MCF5272 operates under big endian mode, but OTG243 operates under the little endian mode.

Software is required to perform byte swapping for the data.

2.3 Hardware Design

This sub-section discusses hardware aspects of interfacing the OTG243 to the MCF5272.

Software considerations are presented in Section 2.3.

The following signals of the OTG243 are involved in the bus interfacing. For simplicity and

clarity, buffers are not inserted between the MCF5272 and the OTG243. One should use his/her

own judgment on this issue based on a specific application.

Operating Mode: /EXVBO and TEST

/EXVBO should be pulled down for 16-bit operation, and the TEST pin must be grounded.

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