Abstract: This invention describes a numeric intensive real-time software development system for programming low cost fixed point digital signal processors (DSP's) and other programmable devices in which code efficiency, ease of programming and code portability are maintained. DSP's being a generic math engine are proliferating into many areas, far beyond the traditional filtering applications. Numeric intensive is the most distinctive nature of the DSP software, and one of the biggest challenges in DSP software development is to implement complicated math algorithms in low cost fixed-point DSP's. The software development system describes an approach where low level assembly language is enhanced with high level syntax and further augmented with an enhance numeric handler for converting between numeric formats. Debug of the DSP programs is aided by the numeric format conversion and the use of high level syntax. The resulting program is written to a driver interface which facilitates porting code between different DSP's.

Abstract: A current reference circuit for use in a memory sense amplifier is described, which generates a mid-point current reference that is insensitive to fabrication process variations. This circuit is also robust enough to handle distinctly different levels of "0" and "1" sense currents without causing clipping of the mid-point reference current. Adequate sensing levels for the bit line sense amplifier are thus ensured.

Abstract: Systems and methods for the detection of motions of a pointed object upon a writing surface such as a touchpad are disclosed. The motions will be detected and converted in an analog-to-digital converter to digital codes representing the location of the pointed object upon the touchpad. The motion will be translated into a pen detect signal indicating the presence of the pointed object upon the touchpad. The digital codes will be filtered to minimize noise and formed into a filtered absolute coordinates digital code. The filtered absolute coordinate digital code and the pen detect signal will be converted to a touchpad-computer interface protocol and transferred to a computer system for further processing.

Abstract: A method and means for the control of a cursor upon a display screen of a computer system by a pointed object such as a pen, stylus, or finger upon an electrical writing surface is disclosed. The method and means will allow the cursor to continue to scroll across the display screen in a fixed direction and at a fixed speed once the pointed object has transited from a workzone region to an edgezone region of the touchpad. Once the pointed object is in the edgezone region, the pointed object may be stopped. If a different direction or speed of movement of the cursor is desired, the pointed object can be moved in the new direction to establish the new direction and speed of movement of the cursor. The control of the cursor will return to the normal movement when the pointed object returns to the workzone from the edgezone.

Abstract: The present invention provides a voltage controlled oscillator with improved noise immunity and minimized variation due to manufacturing process, power supply and operating temperature changes. The voltage controlled oscillator consists of fully differential connected ring oscillator that includes a plurality of differentially connected delay elements. The ring oscillator responds to a control current signal for controlling the frequency of oscillation. A voltage to current converter converts the input tuning voltage to an output current for the controlling of the ring oscillator. The delay element consists of two source coupled P-channel transistors connected to a current source. The drains of the P-channel transistors are each connected to a voltage controlled impedance that changes the delay characteristics of the delay element in response to the input tuning voltage.

Abstract: A system to transfer a serial digital data protocol between a controlling processor such as digital signal processor and a plurality of analog front-end devices is described. The system has a serial clock unit to generate a serial clock reference signal, a serial data control unit to create the serial data protocol, a serial clock transmission medium, a serial data transmission medium, and an analog front-end control unit. The serial digital data protocol has a start bit time, an address time, a read/write bit time, a first high impedance time, a serial data word time, a second high impedance time, and a stop bit time. A serial data word may be transferred either from the controlling processor to the analog front-end device or from the analog front-end device to the controlling processor dependent on the state at the read write bit time.