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LVDS Pin Assignment in Lattice

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imbichie

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Hi Friends,

I am working with Lattice ECP2 FPGA, Now there are some LVDS Input and Output ports in my Design. This is the first time i am using the LVDS ports in my design.

Can i directly assign the LVDS port to the +ve pins of LVDS? Means shall i use any buffer before the assignment to the LVDS pin??

If i am assigning the port to the +ve LVDS pin, then is the FPGA automatically assign the complementary pin to the -ve pin of LVDS??

Thanks in Advance
 

lucbra

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If I remember well, you can just assign the signals to the I/O. This is done in the spreadsheet view (Diamond). In the same view, you chose the desired I/O standard - in your case this becomes LVDS25.
 

imbichie

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Thank you for your Reply,....

So no need of any LVDS Buffer before assigning to the pin. Means just assign the port to the +ve LVDS pin and assigning the type as LVDS25 is enough....?

I just assigned the port to the +ve LVDS pin, then i found (*.pad) that the ispLever itself assigned the complementary to the -ve LVDS pin.
So is it enough, means will it work as LVDS, with out using the buffer at the port???

Thanks in Advance
 

lucbra

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I just assigned the port to the +ve LVDS pin, then i found (*.pad) that the ispLever itself assigned the complementary to the -ve LVDS pin.
So is it enough, means will it work as LVDS, with out using the buffer at the port???

Good - if ispLever (you haven't upgraded to Diamond yet?) assigned the complementary buffer, you are assured that it will send out LVDS signals. However, there is no protocol involved (8b/10b, serdes, ...) That is something that you need to write yourself.

Good luck
 

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