DS3134 datasheet(67/203 Pages) DALLAS

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DS3134

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Receive V.54 Search Routine Table 5.4A

Step #1: Set Up the Channel Search

The Host will determine in which DS0 channels the V.54 search is to take place by configuring the RV54

bit in the R[n]CFG[j] register. If this search sequence does not detect the V.54 pattern, then the Host can

pick some new DS0 channels and try again.

Step #2: Toggle VRST

Once the DS0 channels have been set, the Host will toggle the VRST bit in the RP[n]CR register and

begin monitoring the SLBP status bit.

Step #3: Wait for SLBP

The SLBP status bit reports any change of state in the V.54 search process. It can also generate a

hardware interrupt, see Section 4 for more details.

When SLBP is set, then the Host knows that

something significant has occurred and that it should read the VLB and VTO real time status bits in the

RP[n]CR register.

Step #4: Read VTO & VLB

If VTO = 1, then the V.54 pattern did not appear in this set of channels and the Host can now reconfigure

the search in other DS0 channels and hence move back to Step #1.

If VLB = 1, then the V.54 loop up pattern has been detected and the channel should be placed into

loopback. A loopback can be invoked by the Host by configuring the CNLB bit in the T[n]CFG[j]

If VLB = 0, if the DS0 channels are already in loopback, then the Host will monitor VLB to know when

the loop down pattern has been detected and hence when to take the channels out of loopback. The DS0

channels are taken out of loopback by again configuring the CNLB bits. Move on to Step #1.

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