Browse Prior Art Database

DSP ADDITIONAL OUTPUTS

IP.com Disclosure Number: IPCOM000008782D
Original Publication Date: 1998-Sep-01
Included in the Prior Art Database: 2002-Jul-12
Document File: 1 page(s) / 58K

Publishing Venue

Motorola

Related People

Tobia S. Schwartz: AUTHOR [+3]

Abstract

The DSP56300 (ONYX) Digital Signal Processor family provides a limited number of pins, that in addition to a specific defined function, can be configured as general purpose I/O pins.

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MOTOROLA Technical Developments

DSP ADDITIONAL OUTPUTS

by Tobia S. Schwartz, Joseph Ziv and Ofer Gabay
1. PROBLEM TO BE SOLVED modules (chip select), DRAM row address strobe or additional address bits.

  The DSP56300 (ONYX) Digital Signal Processor family provides a limited number of pins, With this specified functionality, a simple that in addition to a specific defined function, can be external latching device can be used to preserve the configured as general purpose I/O pins. pin state.

Many designs require more I/O pins than the number that the DSP provides.

  The proposed solution takes advantage of the pin polarity control capability, supported by a bit within the Address Attribute Register. This bit. is normally used to define whether the pin will be active high, upon accessing the specified address space.

  By not enabling any external access address space (this is the default configuration during reset) the pin state will be address independent.

The state of the pin can be changed by setting or clearing the polarity bit mentioned above.

This kind of control is similar to the one employed by a specified general purpose output pin.

The specified uses of the AA pins are related to The described solution results with the follow- external program or data space accesses. ing advantages:

When an external memory address in a pre- l No additional hardware is required for the defined space is accessed, the AA pin is asserted. implementation.

The pin is de-asserted at th...