Self-configuring interface circuitry, including circuitry for identifying a protocol used to send signals to the interface circuitry, and circuitry for receiving the signals using the identified protocol

A method for selecting an interface protocol in an integrated circuit having interface circuitry operable in accordance with a predetermined plurality of interface protocols, the integrated circuit including at least one input terminal, the method comprising the steps of:

• accepting input signals from another device on the at least one input terminal, wherein the input signals are transmitted by the other device in accordance with a desired interface protocol;
• analyzing the input signals to determine a signature which corresponds to one of the plurality of predetermined interface protocols;
• providing a selected enable signal from a plurality of enable signals in response to the determined signature, the selected enable signal corresponding to the interface protocol corresponding to the determined signature;
• and
• selecting one of the plurality of predetermined interface protocols responsive to the selected enable signal;
• whereby the desired protocol is selected from the plurality of predetermined protocols.

A method for configuring interface circuitry of an integrated circuit to use a protocol selected from a predetermined plurality of protocols to communicate signals with another device, the method comprising the steps of:

• determining a signature which distinguishes each specific protocol in the predetermined plurality of protocols;
• monitoring at least one of the signals received by the interface circuitry to detect any of the signatures;
• altering a state of the configuration circuit responsive to detecting any of the signatures;
• and
• providing a configuration signal responsive to the state of the configuration circuit, wherein the configuration signal configures the interface circuitry to use the protocol corresponding to the signature detected in the at least one of the signals being monitored.

Configuration circuitry for providing a mode selection signal to an interface circuit of an integrated circuit for configuring the interface circuit to use a selected one of a plurality of interface protocols, wherein the integrated circuit includes a plurality of terminals adapted to receive signals from at least one other device, the configuration circuitry comprising:

• input means coupled to at least one of the plurality of input terminals, the input means being adapted to receive input signals;
• an output means coupled to the interface circuitry;
• and
• latching means, coupled to the input means which monitors the input signals for a signature indicative of a specific one of the plurality of protocols, the latching means also being coupled to the output means to provide the mode selection signal to the interface circuitry.

An interface circuit for an integrated circuit having a plurality of input terminals including chip select, data input, and clock terminals, the interface circuit being operable in accordance with any one of the increment-only, up/down, and SPI interface protocols, the interface circuit comprising:

• interface circuitry coupled to the plurality of input terminals, wherein the interface circuitry processes signals received via the plurality of input terminals in accordance with one of the increment-only, up/down, and SPI interface protocols as determined by a mode selection signal;
• protocol identifying circuitry comprising latch circuits coupled to at least the data input terminal for monitoring signals thereon, and coupled to the interface circuitry for providing the mode selection signal responsive to the detection of a signature within the monitored signals on the data input terminal indicative of a specific one of the increment-only, up/down, and SPI interface protocols;
• and
• reset circuitry for resetting the protocol identifying circuitry to provide a predetermined mode selection signal.