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TI puts ADSL, VoIP, WLAN on one card

Posted: 01 Apr 2004 ?? ?Print Version ?Bookmark and Share

Keywords:ar7? adsl-2/adsl-2+ router chip? texas instruments? ti? reference platform?

Tapping two proprietary interfaces on its AR7 ADSL-2/ADSL-2+ router chip, Texas Instruments Inc. has crafted two reference platforms that support ADSL, voice-over-Internet Protocol (VoIP) and WLAN capabilities on the same board.

The heart of the reference boards is the AR7, the router IC that raised the bar in the digital subscriber line sector in 2003 by combining an ADSL-2/2+ front end, line driver and baseband functionality on a single piece of silicon. TI aims to parlay that integration into system-level designs with its two newly released reference boards.

The first platform is the AR7W, which merges the AR7 DSL router IC and the TNETW1230/TNETW2522 802.11b/g chipset. This board includes a four-port Ethernet switch and interfaces the WLAN chip set to the AR7 through one of TI's low-pin-count VLYNQ interfaces. "It was fairly easy to add WLAN capabilities to a board design," said Mike Spence, product line manager for TI's DSL customer-premises equipment chips.

While the WLAN integration was straightforward, integrating voice capabilities proved more challenging, Spence said.

In building the AR7W platform, Spence said, TI tapped into the external 10/100 Ethernet switch to ease WLAN integration. But when crafting the second board, the AR7VWi, TI had to tweak the Linux source code to support the quality-of-service (QoS) schemes needed to handle voice streams. The second board delivers VoIP, DSL and WLAN connectivity.

To meet QoS requirements, TI developed a Linux network support package that provides four priority queues. TI has also implemented a dynamic packet fragmentation technique. "Fragmentation is needed to hold the 50-millisecond latency requirements for voice services," Spence said.

The AR7VWi platform combines the DSL and WLAN chip sets from the AR7W platform with a VDSP - a TMS320C55x-based digital signal processor optimized for channel-processing tasks. The VDSP also runs TI's popular Telogy VoIP software package. Like the 802.11g chipset, the VDSP links with the other components through a second VLYNQ interface on the AR7 DSL router chip.

Spence said the AR7W can be implemented using approximately 250 components, while the AR7VWi can be implemented using under 400 components. Both reference platforms are available now. TI expects the first systems based on these reference designs to hit the market in June 2004.

- Robert Keenan

EE Times

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