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Altera_Forum
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16 years ago

LVDS tristating usage

Hello, 1. Could anybody suggest whether ALT_OUTBUF_TRI_DIFF can be used at the moment? I was trying to select Cyclone III, Stratix IV - and it looks like this primitive does not supported at ...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
16 years ago

Yes,

I agree that there is no sence to tri-state inputs.

But what about output pins tri-stating?

I have multiply slaves and It is necessary to avoid signal contention on the slave output (looks like SPI multi-slave environment).

So I need to use tri-state buffers and my bus is LVDS bus.

When I connected the slave output line to the tri-state buffer and selected the LVDS standatrd for it I got the following error:

Error: The differential I/O standard LVDS cannot be used on the pin Slave_O, because the specified pin uses a tri-stated output buffer.

Does it mean that it is not possible to tri-state LVDS in all Altera devices?

What can be a workaround for this problem?