Abstract: A wrap back test system and method for providing local fault detection within a section of an integrated I/O interface core device on an integrated circuit is disclosed. The system and method of this invention is suitable for use in any I/O interface having both a transmitter and a receiver section. The wrap back of input test data, prior to reformatting for transmission, to the receiver's data alignment stage permits fault detection within the core of an integrated I/O interface. By illustration, in a serializer/deserializer I/O, the wrap back of alignment pattern encoded parallel data, prior to serialization, to the receiver's data alignment stage permits identifying faults in just this portion of the I/O transceiver. The wrap back test system and method of this invention permits fault isolation of within the boundaries of the I/O core and independent of external logic or testers.

Abstract: A character programming method (10) whereby a synchronization character (17) can be determined in a determine encoding scheme operation (12) and a determine synchronization character operation (14). The synchronization character (17) can then be programmed into a synch character logic (26) of an integrated circuit (20) or a core (20) thereof. The synch character logic (26) can be programmed through a plurality of program pins (30) on the periphery of the integrated circuit (20) or by more sophisticated means such as by sending the programming from a sending integrated circuit (40) to a receiving integrated circuit (42) through a communications line (44).

Abstract: A test method and means for in integrated circuit (10) having asynchronous communication capabilities including a transmitter (12) and a receiver (14). A pattern generator (24) is provided for generating patterns directly from within the integrated circuit (10). In the best presently known embodiment, a serializer (16) provides a serial output (20) and a deserializer (18) processes a serial input (22) into a parallel signal and provides the parallel signal to a receiver (14). The pattern generator (24) is preprogrammed to provide a parallel data pattern which can optionally and intermittently be provided to the transmitter (12) in a test mode (44). In the test mode (44), signal is routed from the serializer (16) directly to the deserializer (18) via an external loop back path (34) or an internal alternative loop back path (34a).

Abstract: A loop back test system and method for providing local fault detection within the core or macrocell of an integrated I/O interface device on an integrated circuit is disclosed. The system and method of this invention is suitable for use in any I/O interface having both a transmitter and a receiver section. The loop back of input test data from the transmitters output directly to the receiver's input permits fault detection within the core of an integrated I/O interface. By illustration, in a serializer/deserializer I/O, the loop back of serialized, alignment pattern encoded parallel data from the output stage of the I/O transmitter to the receiver's input stage permits identifying faults occurring within the integrated I/O transceiver macrocell. The loop back test system and method of this invention permits fault isolation of within the boundaries of the I/O core and independent of external logic or testers.

Abstract: A means and method for testing high speed phase locked loops (13) in an integrated circuit (12) at a test frequency lower than the operation speed of the phase locked loop (13). A test circuit portion (10) repeatedly tests for a zero level (42) of a recover clock signal (34) from the phase locked loop (13) and a latching flip flop (26) is set to provide a lock indication output (30) as long as repeated samples, taken at a test time (38) continue to indicate a zero level (42) of the recover clock signal (34). The test time (38) is the leading edge (40) of a reference clock signal (36) provided from an external source at a reference clock input (28) to the integrated circuit (12).