Rainbow Electronics DS2152 - Manual (Page 25)

DS2152
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– CCR7.6 Remote Loopback.
0 = loopback disabled
1 = loopback enabled
– CCR7.5 Not Assigned. Should be set to zero when written to.
– CCR7.4 Not Assigned. Should be set to zero when written to.
– CCR7.3 Not Assigned. Should be set to zero when written to.
– CCR7.2 Not Assigned. Should be set to zero when written to.
– CCR7.1 Not Assigned. Should be set to zero when written to.
– CCR7.0 Not Assigned. Should be set to zero when written to.
Power–Up Sequence
On power–up, after the supplies are stable, the DS2152
should be configured for operation by writing to all
of the
internal registers (this includes setting the Test Regis-
ters to 00Hex) since the contents of the internal regis-
ters cannot be predicted on power–up. Finally, after the
TSYSCLK and RSYSCLK inputs are stable, the ESR bit
should be toggled from a zero to a one (this step can be
skipped if the elastic stores are disabled).
Remote Loopback
When CCR7.6 is set to a one, the DS2152 will be forced
into Remote LoopBack (RLB). In this loopback, data
input via the RPOSI and RNEGI pins will be transmitted
back to the TPOSO and TNEGO pins. Data will con-
tinue to pass through the receive side framer of the
DS2152 as it would normally and the data from the
transmit side formatter will be ignored. Please see
Figure 1–1 for more details.