Diagnostic Signals; Loopback; Table 5-3: Loopback Modes - Xilinx RocketIO X User Manual

Diagnostic Signals

Table 5-2: LOC Grid and Package Pins Correlation for FF1704 Packages
Diagnostic Signals
Often a diagnostic check is needed upon power-up. RocketI/O X transceivers have several
inputs and outputs to run these checks.

Loopback

LOOPBACK allows the user to send the data that is being transmitted directly to the
receiver of the transceiver.

Table 5-3: LOOPBACK Modes

RocketIO™ X Transceiver User Guide
UG035 (v1.5) November 22, 2004
LOC Constraints
GT_X6_Y0
GT_X6_Y1
GT_X7_Y0
GT_X7_Y1
GT_X8_Y0
GT_X8_Y1
GT_X9_Y0
GT_X9_Y1
LOOPBACK[1:0]
00 Normal operation. Not in loopback. The transmitted
data is sent out from the differential transmit ports
(TXN, TXP) and is sent to another transceiver without
being sent to its own receiver logic. During normal
operation, the LOOPBACK should be set to 00.
01 Internal parallel loopback. This mode is used to check
the PCS function. The PMA is not included.
10 Post-driver serial loopback (after the TX output buffer).
This mode is used to check that the entire transceiver is
working properly. This includes testing both the PCS
and PMA functions. This emulates what another
transceiver would receive as data from this specific
transceiver design
11 Pre-driver serial loopback (before the TX output
buffer). Same as above, but not including the TX output
buffer. The output buffer can be disabled in this
loopback mode.
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FF1704
XC2VPX70
BB17, BB16, BB15, BB14
A17, A16, A15, A14
BB13, BB12, BB11, BB10
A13, A12, A11, A10
BB9, BB8, BB7, BB6
A9, A8, A7, A6
BB5, BB4, BB3, BB2
A5, A4, A3, A2
Table 5-3 shows the four modes for loopback.
Description
R
127