PURPOSE: A UTOPIA(Universal Test amp; Operations PHY Interface for ATM) interface method between slave mode devices are provided to perform a utopia interface between two ATM(Asynchronous Transfer Mode) devices operating with a slave mode. CONSTITUTION: In a waiting state(IDLE state), an OCA(Output Cell Available) and an ICA(Input Cell Available) transit an active 'high' state and so when a CA value as an operation value of logical sum of the OCA and ICA becomes an active 'high', a UTOPIA interface circuit transits first an ORDENB(Output Read Enable Block) signal to an active 'low' state and then outputs an IWRENB(Input Wire Enable Block) signal to an active 'low' state. Then, a data cell transmission is performed between an RCMP and an ATLAS(step 2). When the OCA transits a non-active 'low' state and so the CA value becomes a non-active 'low' state, the ORDENB signal and IWRENB signal are maintained as an active 'low' state so that 4 words may be transmitted more(steps 3,4 and 5).
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