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© MiMOMax 2013 Four Wire Audio
Interface Manual
5.2.3
HSSI Cross Over
It is possible to connect 2 Four Wire Audio units back to back for testing where any enabled
audio channel will pass unrestricted, some limitations apply to the COM port while the cross
over is in place.
The Audio ports will behave as they would if the FWA units were part of a normal point to
point system. If a channel is configured for E&M signalling then the E-Lead signal is similarly
required for audio to pass.
The COM port is designed to accommodate on-demand operation so until it can be
determined that the Air Interface is active, data is buffered. Therefore when testing the COM
port with a cross over cable, an audio channel should also be active to ensure unrestricted
data flow.
Image with two Four Wire Audio units connected by a HSSI crossover cable
HSSI X-Over Cable
Unit One : RJ45
Unit Two : RJ45
Signal
Pin
Pin
Signal
Tx Clock A
8
6
Rx Clock A
Tx Clock B
7
3
Rx Clock B
Tx Data A
2
5
Rx Data A
Tx Data B
1
4
Rx Data B
Rx Clock A
6
8
Tx Clock A
Rx Clock B
3
7
Tx Clock B
Rx Data A
5
2
Tx Data A
Rx Data B
4
1
Tx Data B
Shield / GND
Body
Body
Shield / GND
