1999-02-08 , S/IC-2034/43
Product News From Philips Semiconductors

Intelligent interrupt arbitration technology at the heart of new UART products

Philips Semiconductors, the world's leading supplier of Universal Asynchronous Receiver Transmitter (UART) devices for industrial and high performance applications, today announced the availability of two new products, an 8-channel UART and a 4-channel UART, both of which significantly lower the burden of interrupt handling, a significant performance issue for Internet access applications. Philips Semiconductors' unique Intelligent Interrupt Arbitration (I2A) technology delivers this solution, thereby saving valuable bus cycles and processor loading and subsequently improving the overall system performance.

"The I2A technology offers a significant performance breakthrough for a product category that has changed very little in the past five years," said Benno Ritter, product marketing manager, Wireless Connectivity Products for Philips Semiconductors. "With the growing opportunity for a new class of Internet connected appliances, developers are searching for low cost solutions that meet the performance demands of users. The I2A technology delivers the answer."

A UART is the electronic circuit that converts parallel bytes from the processor into serial bits for transmission, and vice versa. In a typical application the UART may interface to several peripheral devices such as a mouse, keypad or a modem. With I2A technology, the new Philips Semiconductors UARTs can identify the highest priority interrupt request and channel it to the processor first. Previously, this arbitration was done by the processor, diminishing the time available for handling other functions. I2A technology helps free up the processor, as well as reduce processor to UART communication time, improving system performance noticeably.

To minimize the overhead associated with interrupt servicing, the I2A technology arbitrates between multiple interrupt requests and reports the context of the interrupting UART through modification of the interrupt vector. The information contained in the interrupt vector includes device location, type of interrupt, priority and the fill level of the FIFO. The result is a significant reduction in the number of processor cycles necessary for monitoring and servicing interrupt requests. For certain applications where the number of interrupt requests are high, the overhead associated with servicing these interrupts may be reduced by a factor of seven or more.

The newest additions to the Philips Semiconductors family of UARTs, the  SC28L198A Octal and the  SC28L194A Quad devices, feature a three byte character recognition system and a sixteen byte FIFO per transmitter and receiver for each channel. The character recognition system may be used for automatic multi-drop address detection, Xon/Xoff recognition or general purpose recognition. Global interrupt and control registers are also provided to ease setup and interrupt handling. Both products operate with supply voltages of 3.3V to 5.0V and are compatible with the 68XXX and x86 microprocessor bus interface, making them well suited for a variety of applications in which data traffic is high. The new UARTs could offer enhancements in the following applications: Internet access equipment, point-of-sale terminals, gas pump automatic payments, high-end modems, robotics, high-end PC workstations and other applications where interrupt arbitration is required for a processor to manage multiple devices.

The integration of 8-channels into one IC (SC28L198A) as well as the integration of 4-channels into one IC (SC28L194A) allows for decreased chip count and therefore board space of existing designs, subsequently leading to substantial cost savings. Small package outline and low power consumption makes this product perfect for cost and power sensitive functions. All commercial products are specified for industrial temperature range.

Philips Semiconductors, a division of Royal Philips Electronics, headquartered in Eindhoven, The Netherlands, is the eighth largest semiconductor supplier in the world (according to Dataquest's preliminary 1998 ranking by sales). Philips Semiconductors' innovations in digital audio, video, and mobile technology position the company as a leader in the consumer, multimedia and wireless communications markets. Sales offices are located in all major markets around the world and are supported by systems labs.