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Method for a true ATA PIO mode-4 interface for a 32-bit RISC wireless processor to a standard IDE hard drive using the processor’s built-in PCMCIA controller pins

IP.com Disclosure Number: IPCOM000009257D
Publication Date: 2002-Aug-13
Document File: 4 page(s) / 91K

Publishing Venue

The IP.com Prior Art Database

Abstract

Disclosed is a method for a true ATA programmed input/output (PIO) mode-4 interface for a 32-bit RISC wireless processor to a standard IDE hard drive using the processor’s built-in PCMCIA controller pins. Benefits include improved performance.

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Method for a true ATA PIO mode-4 interface for a 32-bit RISC wireless processor to a standard IDE hard drive using the processor’s built-in PCMCIA controller pins

Disclosed is a method for a true ATA programmed input/output (PIO) mode-4 interface for a 32-bit RISC wireless processor to a standard IDE hard drive using the processor’s built-in PCMCIA controller pins. Benefits include improved performance.

Background

        � � � � � In the emerging area of low-power embedded computing, a requirement exists for mass-storage elements in devices. Multimedia applications, such as mp3 players and video playback devices, process content comprised of extremely large amounts of data. Conventionally, for handheld wireless devices, the most demanding mass-storage requirements (>2 GB) can only be met by PCMCIA storage cards containing rotating media disk drives.

        � � � � � In this setup, the storage elements are removable devices compliant with the PCMCIA standard. The PCMCIA devices hook up to the built-in PCMCIA/CF controller on the processor. To communicate with the removable media, the software running on the Cotulla utilizes an ATA driver on top of PCMCIA manager services functionality, which together forms a PCMCIA-ATA interface. However, if a device is to contain a large fixed element storage device (that is physically unremovable), using the PCMCIA-ATA interface requires unnecessary additional system overhead. In terms of software, this overhead includes running the PCMCIA manager services layer that controls the PCMCIA-specific registers and insertion/detection events. In terms of hardware, this overhead includes an extra application-specific integrated circuit (ASIC) for the PCMCIA-to-ATA bridge and additional packaging costs.

        � � � � � Most large disk drives today have a true ATA interface that is an industry standard in the PC realm. However, a true ATA interface, rather than a PCMCIA-ATA interface, in the embedded-processor arena is unknown.

Description

        � � � � � The disclosed method is a true ATA PIO mode-4 interface for a 32-bit RISC wireless processor to a standard IDE hard drive using the processor’s built-in PCMCIA controller pins. To utilize large ATA disk drives and leverage ATA drivers already in place in software that runs on the processor, an interface from the processor directly to the drive with minimal glue logic can be implemented. This interface uses the actual pins from the processor’s PCMCIA control logic block but with the PCMCIA manager services software stack and the unused PCMCIA pins removed from the system (such as card detect, extra address lines, and extra control lines). The software enables the registers that indicate a card is in place, enabling the pins and bypassing the entire card services stack.

        � � � � � The memory bus (address/data) and PCMCIA control pins hook up to implement the ATA interface (see Figure 1). The illustration indicates all the required hardware and logic to communicate with the hard disk...