DIGITAL KEY TELEPHONE SET AND DIGITAL KEY TELEPHONE SYSTEM

摘要

A clock generating circuit generates a clock of a rate corresponding to a Dch rate in response to a specification from the exterior. A counting circuit detects completion of reception of one frame by counting the clock number up to "11" at timing at which a start bit detecting circuit detects a start bit in a serial signal. An S/P converting circuit fetches a serial Dch signal bit by bit in synchronism with the clock, outputs the latest fetched 10 bits in a parallel form and latches eight bits of a real data portion among the output data into a latch circuit at the time when reception of one frame is completed. In parallel with the above operation, a parity calculating circuit and flag/interruption generating circuit set various flags and generate a reception completion interruption.