Polling of failed devices on an i.sup.2 c bus

Abstract

Polling of devices on an inter-IC (I.sup.2 C) is provided. An expansion processor resides on a primary I.sup.2 C bus. The expansion processor is coupled to a plurality of I.sup.2 C sub-buses each of which may host a plurality of I.sup.2 C devices. Data is transferred between the expansion processor and the plurality of I.sup.2 C devices via the corresponding sub-bus according to an I.sup.2 C protocol. Data transfer is in response to a request initiated by a bus master on the primary I.sup.2 C bus. The bus master communicates with a target device residing on one of the sub-buses by addressing the expansion processor. The bus master informs the expansion processor of the target device by sending the expansion processor a number of the sub-bus on which the target device resides, and an address of the target device. A data stream bound for the target device is directed to the expansion processor which then echos it to the target device. Likewise, a data stream bound from the target device to the bus master on the primary I.sup.2 C bus is transmitted to the expansion processor which then echos it to the bus master. Each of the target devices on the sub-bus can be polled to determine if they have failed. Failure of a device only affects operation of its sub-bus.