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Electronic Design

MIPS RISC Plus Communication Peripherals Equals DSL Gateway

Many homes and small office/home office (SOHO) DSL-linked environments require more than a simple DSL computer connection. A good number incorporate a local-area network (LAN) base with multiple computers, network appliances, and phones. More-sophisticated connections are needed to support a multifaceted gateway between the DSL link and the SOHO customer premise equipment (CPE).

The TC32355, IDT's communications platform chip, does the job. Delivering a complete hardware/software DSL gateway, it integrates a 150-MHz, 32-bit MIPS RISC processor with telephone, DSL, fiber, or wireless interfaces, and Ethernet, Home PNA, or wireless media interfaces.

This is a functioning platform with memory, PCI, and PCMCIA interfaces for local memory and additional peripheral add-ons. It supports 10/100-Mbit/s Ethernet with up to four MAC addresses. Also, it supports ATM with an on-chip SAR-supporting Utopia 1, 2 bus. The TC32355 additionally supports USB for linking to a PC host and peripherals. And, it supports a telephony time-division multiplexing (TDM) bus interface with up to four voice channels, along with audio analog-to-digital converters and digital-to-audio converters.

Its MIPS processor runs VxWorks and Tornado for Home Gateways, enabling it to function as a home gateway. The processor also does high-level work as an IP router, and it conducts bridging between the local Ethernet and the wide-area network (WAN) ATM, IP, IPoA, or PPP protocols.

The MIPS 32-bit RISC is the SOHO gateway chip's core. Running at 150 MHz, the scalar processor incorporates 8-kbyte instruction and 2-kbyte data caches. The CPU system bus runs at 75 MHz and links to off-chip memory. Additionally, the chip has a 300-Mbyte/s internal IP bus, and it incorporates a 16-channel DMA controller to offload the CPU from processing I/O transfers. Peripherals include three counter/timers, a watchdog timer, two UARTs, an I2C serial bus controller, a GPIO interface, and a hardware interrupt controller.

The TC32355 comes in a 208-pin QFP and dissipates 1.8 W. Full production is scheduled for June. It's available in 130- and 150-MHz speeds. Prices start at $22 in quantities of 10,000 units. IDT also supplies a reference gateway design.

Integrated Device Technology, 2975 Stender Way, Santa Clara, CA 95054; (800) 345-7015;

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