Comms bridge gives MP3 players FireWire speed

The OXFW900 FireWire to IDE bridge chip is enabling OEMs to design FireWire ready MP3 players able to download a CD album in under 6 seconds. Exploiting the versatility of the device's embedded ARM7 processor and firmware, a new reference design from Oxford Semiconductor supports data transfer speeds up to 14MBps.

Combining the OXFW900 with a 1394 PHY, Flash, MP3 decoder, DAC, CPLD and an LCD, the MP3 player reference design supports any 2.5 inch hard disk - a 5GB unit being sufficient to store 70 albums of music. Trials determine that a 65 minute long CD encoded at 160kbps can be downloaded via the bridge chip at 5.7 seconds compared with 1 minute 15 seconds for a USB solution.

The OXFW900 IEEE 1394 to ATA / ATAPI interface design supports the standard FAT32 filing system allowing music to be catalogued by genre, artist, album and track and hard disk storage of any other data type.

Featuring an integrated serial bus protocol (SBP-2) target controller, the OXFW900 is simple to design in, being supported by all common operating systems. Request blocks defined by the SBP-2 protocol are translated by an on-chip ORB co-processor into IDE commands which automatically stores return messages at a host address.

An integral PHY-Link interface complies with both 1394-1995 and 1394A specifications and, using a combination of the ARM7TDMI processor, ORB coprocessor and a buffer manager, the1394 transaction layer and SBP-2 protocol are fully implemented.

Offering a RAM bandwidth of 800Mbps, the high performance buffer manager serves to reduce latency and improve data throughput. Without processor intervention, it provides automatic storage and distribution of 1394 and ATA/ATAPI packets and ORB requests.

Planned revisions for the OXFW900-based MP3 player reference design will focus on miniaturisation, through the use of PCMCIA style 1.8 inch drives and a reduction in circuit component count. A graphic LCD will also be added.