| 摘要 |
A multimedia protocol interface for 64 kbit/s data flow organised according to the frame structure specified in CCITT Recommendation H221, and transmitted and received according either to the standard 64 kbit/s protocol or the 256 kbit/s IOM protocol, is provided which can operate either autonomously or aided by an external microprocessor. It comprises a receiver, a transmitter, and control block and means for local loop testing of the operation of the interface. The external microprocessor can read both the received data and information relating to the receiver operation, and can also send data to be transmitted or can read information relating to the transmitter operation. The receiver receives data, and clock and synchronism signals, and outputs the received data, associated with timing signals useful for external devices connected to the interface for data recovery. The transmitter transmits the data, receives clock and synchronism signals, and supplies data and timing signals to the external devices. Local testing is carried out by verifying whether the receiver succeeds in recovering synchronism from a signal transmitted by the transmitter of the same interface, under microprocessor supervision, and whether the data are correctly transmitted and received.
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