| 摘要 |
PURPOSE: A PCM(Pulse Code Modulation) interface device for testing a digital trunk line is provided to be connected between a DPRAM(Dual Port RAM) and a time switch when the digital trunk line is tested, and to transceive test-related data, so as to prevent memory collisions caused when a DSP(Digital Signal Processor) and a PCM interface access the same DPRAM. CONSTITUTION: The first selector selectively outputs PCM(Pulse Code Modulation) serial data through two highways. S/P(Serial to Parallel) converters(306,309) convert the PCM serial data into PCM parallel data. A buffer buffers the PCM parallel data, and outputs the buffered PCM parallel data to two DPRAMs(Dual Port RAMs). P/S(Parallel to Serial) converters(307,308,310,311) convert the PCM parallel data outputted from the two DPRAMs into PCM serial data. The second selector outputs the PCM serial data converted in the S/P converters(306,309) to the highways, as many as the number of preset channels. A timing controller(322) timing-controls an inputted output enable signal, read/write signals, and a reset signal. If one of the DPRAMs is simultaneously accessed by a DSP(Digital Signal Processor) and a PCM interface, the timing controller(322) generates the first address signal, the second address signal, a signal for controlling a buffering operation of the buffer, a signal for controlling selecting operations of the selectors, a DPRAM write enable signal, and a DPRAM read enable signal. The first address signal makes the DSP access a half area of a corresponding DPRAM. The second address signal makes the PCM interface access the rest half area.
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