For its second generation of USB microcontrollers, Cypress Semiconductor has taken the microcontroller itself out of the loop and concentrated on building hardwired logic to implement the most commonly used parts of the USB protocol.
The decision, made to support the 480Mbit/s maximum speed of the recently released USB 2.0 specification, will make it possible for the company to implement several designs due out later in the year. They include a new type of hub controller and a USB 'front-end' for commodity products such as printers and scanners where designers do not want the cost overhead of a second microcontroller. A dedicated design for mass storage, using a glueless interface to ATAPI-based disk drives is also expected.
Norman Taffe, director of marketing for USB products at Cypress said the 480Mbit/s would create new market for addon storage products.
"People won't have to upgrade their PCs just to get more hard disk space. They will decide just to plug a new drive in using USB," he said.
The initial chip, which Taffe said Cypress is sampling now, is an integrated microcontroller-based design. As with the company's previous USB products, brought in through the acquisition of Anchor Chips, the FX2 is based on an 8051 core.
Because this has a relatively slow cycle time, the Cypress designers implemented a state machine to handle the USB data-transfer and device-management, or enumeration, protocols. This serial interface engine (SIE) passes data to an from what Taffe terms a "quantum FIFO".
In effect this is a dual-port memory separated into blocks that are allocated on a channel-by-channel basis. By passing the channel ID, different tasks or devices accessing the local-bus side of the can access the FIFO without interfering with each other. On the USB side, the SIE accesses different channels in the quantum FIFO depending on which one is currently actively transferring data across USB. This should simplify the design of peripherals that mix isochronous and 'bursty' channels.
A small amount of programmable logic lets the FX2 talk to ATAPI, Utopia or enhanced parallel port interfaces without external glue logic. For the dedicated mass-storage version, Cypress will strip the logic back to support just ATAPI.
The stripped-down SX2, expected to sample later this year alongside the hub and disk-drive versions, removes the 8051 core.
Although Taffe said peripheral designers were building USB 2.0 into next-generation products and software was progressing well as Microsoft, he reckoned that USB 2.0 sales during 2001 would be lower than analysts' estimates.
"About a half million will be shipped this year," he said.
Some analyst projections had put the USB 2.0 market at more than 32m in 2001, against a total of 238m for USB 1.1 devices.