Scenix Semiconductor, Inc.

Advanced Micro Devices Corporation

Ubicom Gmbh

Kinyue Szeto

Charles M Gracey, Iii

Ravi Sharma

Nicholas J Kelsey

Chuck Cheuk-wing Cheng

Chih-Siung Wu

Chuck Cw Cheng

An apparatus and method to provide a data processing system with reduced average power consumption while maintaining fast interrupt handling, and/or selectively change clock frequency for accessing memory with various access speeds. In a first embodiment, the invention provides a method to deterministically change a clock frequency between a first clock frequency and a second clock frequency in a data processing system to process operations upon the occurrence of a condition. In a second embodiment, the invention provides a method to change the clock frequency of a data processing system to process operations upon the occurrence of a condition. In a third embodiment, the invention provides a clock divider circuit to produce a core clock signal. In a fourth embodiment, the invention provides a data processing system with a deterministically variable processor clock.

Apparatus and method of dynamic and deterministic changes in clock frequency for lower power consumption while maintaining fast interrupt handling

An in-system debugging (ISD) capability is incorporated into a production microcontroller. The ISD capability is incorporated without the costly addition of any extra pins to read out the data for debugging by using the oscillator pins of the production microcontroller to read out the data. Building such an ISD capability into the microcontroller, enables debugging to be performed on the actual production board (instead of a special debug board) having the actual production microcontroller (instead of a bond-out microcontroller). This allows designers to debug programming using the actual production system instead of an emulation system.

Non-intrusive in-system debugging for a microcontroller with in-system

A method and apparatus for In-System Programming which overcomes the above-described disadvantages. The method and apparatus of the ISP system interfaces with the two oscillator (instead of I/O) pins on the microcontroller. By interfacing with the two oscillator pins, the need for extra isolation circuitry to isolate other circuits from the ISP circuits is avoided in most circumstances, without incurring the expense of an expensive JTAG tester or extra dedicated pins. The amount of isolation circuitry necessary is reduced because the two oscillator pins are usually connected to passive components (registers, capacitors, or crystals) which cannot be damaged by the relatively high programming voltages and which do not produce signals that would interfere with the ISP programming signals.

Non-intrusive in-system programming using in-system programming

A glitch filter for eliminating noise pulses less than 12 nanoseconds (ns) created by large devices on the SCSI bus and reflections of the 12 ns pulses created by a long SCSI bus cable, as well as noise pulses on the order of 35 ns typically found on a SCSI bus. The glitch filter includes a Schmitt trigger connected to receive the SCSI bus signal along with three filters connected in series with the Schmitt trigger. The first filter removes positive pulses having a pulse width less than 12 ns and provides an inverted output. The second filter removes negative pulses having a pulse width less than 12 ns and provides an inverted output. The third filter removes pulses having a pulse width less than 35 ns and provides the output of the glitch filter.

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San Francisco, CA, United States of America

Kinyue Szeto