/ mapping/demapping converting circuit in SDH

摘要

PURPOSE: A mapping/demapping conversion circuit in the SDH(Synchronous Digital Hierarchy) layer is provided to perform a read/write operation to a VC(Virtual Container) memory without using a separate memory when mapping VC11 into TU(Tributary Unit)12 or demapping TU12 into VC11. CONSTITUTION: A memory unit(100) stores data by a unit of VC. A transmission pointer generating unit(110) adds a pointer to VC 11 data. A read enable generating unit(120) receives TU 12 role mapping STM payload signal and disables an unnecessary portion in VC 11. A write enable generating unit(130) disables an unnecessary portion in VC11 when writing data to a VC memory. A mode register unit(140) stores VC11, TU12 modes by channels. A payload disable unit(150) analyzes an input VC count and produces a necessary disable signal. A comparing unit(160) compares the disable signal to the LSB(Least Significant Bit) of VC count. An AND gate(170) performs an AND operation with the payload enable and disable signals.