SP508EB Datasheet, PDF (7/10 Pages) Sipex Corporation – Evaluation Board Manual

USING THE EVALUATION BOARD: continued
Driver Receiver Remote Loopback.
The following example uses the ST driver
looped back into the TxC receiver, using the
3 bit decoder configure the SP508 for the
desired protocol. Connect a jumper cable
between the ST(a) pin and the TxC(a) pin. If
your mode select is for a differential driver/
receiver, then also connect a jumper cable
between the ST(b) pin and the TxC(b) pin.
next connect a signal generator to the ST
input pin. The signal generator output must
be a TTL-level output at a frequency within
the acceptable range of the driver mode
under test. Be sure that the STEN and the
TxCEN DIP switches are set to enable the
ST driver and TxC receiver and that the DIP
switches tying the ST driver to the TxC
receiver are off (refer to section 5.0 Dip
switch guide). The driver outputs are now
connected back to the receiver inputs so
that the driver input to receiver output can
be examined. This configuration is similar
for the other drivers.
Driver Receiver Local Loopback
The SP508 has the ability to provide an
internal loopback. This feature is invoked by
a logic “0” on the LOOPBACK pin. The
driver input and receiver output characteris-
tics adhere to the appropriate specifications
outlined in the data sheet under loopback
conditions. The LOOPBACK pin has in in-
ternal pull-up resistor so that the SP508
defaults to normal operation during power-
up or if the pin is left floating.
DCE DTE selectable configuration
• Configure the decoder for the desired
mode.
• The SP508 evaluation board has dip
switches setup to allow for the evaluation
of a selectable DCE DTE configuration.
• Switch the STEN and RRCEN to the ON
position. This will disable the ST and RRC
driver outputs. (Refer to the DIP switch
guide on Page 8)
• Switch the <TxCEN> and <RRTEN>
switches to the ON position. This will dis-
able the TxC and RRT receiver inputs.
(Refer to the DIP switch guide on Page 8)
• Switch the ST(A), ST(B), TxC(A), and
TxC(B) switches to the ON position. This
ties the ST driver outputs to the TxC Re-
ceiver inputs.
• Switch the RRC(A), RRC(B), RRT(A), and
RRT(B) switches to the ON position. This
ties the RRC driver outputs to the RRC
receiver inputs.
• To enable a DTE configuration switch the
STEN and RRCEN switch to the OFF
position. Be sure the TxC and RRT receiv-
ers are disabled by switching the TxCEN
and RRTEN switches to the ON position.
(Refer to the DIP switch guide on Page 8)
• To enable a DCE configuration switch the
TxCEN and RRTEN to the OFF position.
Be sure to disable the ST and RRC driver
outputs by switching the STEN and RRCEN
switches to the ON position. (Refer to the
DIP switch guide on Page 8)
System Level Evaluation
• The DB-25 Connect if configured as a DTE
for EIA-530 pinout. In order to connect
other DCE equipment or network analyz-
ers ( i.e. the TTC Firebird 6000A), the RxC
receiver output must looped back into the
TxCE driver input. The RxD output can
also be looped back to the TxD input.
• If connecting the evaluation board to a
microcontroller such as the Motorola
MC68360, jumper wires of the driver in-
puts and receiver outputs must connect to
the µC’s appropriate pins.
rev. 7/7/03
SP508 Evaluation Board Manual
7
© Copyright 2003 Sipex Corporation