Texas Instruments Corporation

Sun Microsystems, Inc.

Ling Cen

Robert W Milhaupt

James Bridgwater

Louise Y Yeung

An interface circuit, coupled between a first circuitry that is synchronous to a first clock (sclk) and a second circuitry that is synchronous to a second clock (mclk), for transferring data between the first and second circuitry and achieving a fast turn-around time between a data request from the mclk domain circuitry and a bus request in the sclk domain. A first FIFO buffer for transferring data from the first circuitry to the second circuitry is provided. Logic associated with the first FIFO to synchronize reads and writes to the first FIFO is also provided. A read Bus Request Enable Generator provides a read bus request enable signal to the first circuitry, and an At_least_x_words_filled Flag Generator provides a plurality of flags, which indicate degrees of fullness of the first FIFO buffer to the second circuitry. A second FIFO buffer transfers data from the second circuitry to the first circuitry. Associated logic for synchronizing reads and writes to the second FIFO buffer is provided. A write Bus Request Enable Generator provides a write bus request enable signal to the first circuitry, and an At_least_y_words_empty Flag Generator provides a plurality of flags, which indicate degrees of emptiness of the second buffer to the second circuitry.

Method and apparatus for dynamically calculating degrees of fullness of a synchronous FIFO

An interface circuit, coupled between a first circuitry that is synchronous to a first clock (sclk) and a second circuitry that is synchronous to a second clock (mclk), for transferring data between the first and second circuitry and achieving a fast turn-around time between a data request from the mclk domain circuitry and a bus request in the sclk domain. A first FIFO buffer for transferring data from the first circuitry to the second circuitry is provided. Logic associated with the first FIFO to synchronize reads and writes to the first FIFO is also provided. A read Bus Request Enable Generator provides a read bus request enable signal to the first circuitry, and an At.sub.-- least.sub.-- x.sub.-- words.sub.-- filled Flag Generator provides a plurality of flags, which indicate degrees of fullness of the first FIFO buffer to the second circuitry. A second FIFO buffer transfers data from the second circuitry to the first circuitry. Associated logic for synchronizing reads and writes to the second FIFO buffer is provided. A write Bus Request Enable Generator provides a write bus request enable signal to the first circuitry, and an At.sub.-- least.sub.-- y.sub.-- words.sub.-- empty Flag Generator provides a plurality of flags, which indicate degrees of emptiness of the second buffer to the second circuitry.

Method and apparatus for dynamically calculating degrees of fullness of

An electronic device (PPU 110) includes a data source (7201) supplying data and successive control signals indicative of valid-data, wherein transitions occur in the data during intervals between the signals indicative of valid-data, and a selector (7205) having a first input connected to the data source (7201), and a second input (7214), and an output. A circuit (7207) is connected to the output of the selector (7205) to receive data from the data source (7201) via the selector (7205). A source of a quieting signal (7220) is connected to the second input (7214), and the selector (7205) is responsive to the control signals (7206) to select the quieting signal (7220) during at least a portion of the interval between the signals indicative of valid data, and to select the data source in response to at least some of the successive control signals indicative of valid-data. Other devices, systems and methods are also disclosed.

System management mode circuits systems and methods

System management mode circuits, systems and methods

An electronic device (PPU 110) includes a data source (7201) supplying data and successive control signals indicative of valid-data, wherein transitions occur in the data during intervals between the signals indicative of valid-data, and a selector (7205) having a first input connected to the data source (7201), and a second input (7214), and an output. A circuit (7207) is connected to the output of the selector (7205) to receive data from the data source (7201) via the selector (7205). A source of a quieting signal (7220) is connected to the second input (7214), and the selector (7205) is responsive to the control signals (7206) to select the quieting signal (7220) during at least a portion of the interval between the signals indicative of valid data, and to select the data source in response to at least some of the successive control signals indicative of valid-data. Other devices, systems and methods are also described.

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Beaverton, OR, United States of America

Ling Cen