Intel® Quartus® Prime Software
Intel® Quartus® Prime Design Software, Design Entry, Synthesis, Simulation, Verification, Timing Analysis, System Design (Platform Designer, formerly Qsys)
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LVDS is input only in CycIII? no way!

Altera_Forum
Honored Contributor II
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I just received the following error message from QuartusII using a CycIII for LVDS outputs. The errored pins are in bank 4. 

 

"Error: I/O standard LVDS on output or bidirectional pin DAC_data1p is illegal -- I/O standard only allowed on input pins" 

 

 

Anyone know why this is happening? 

 

Thank you in advance, 

BR
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Altera_Forum
Honored Contributor II
452 Views

In general, LVDS is allowed for both inputs and outputs. Maybe there is a Cyclone III restriction for the particular side of the device you are using. (In some device families, pins on the top/bottom sides have LVDS support different from that on the left/right sides.) 

 

Right-click the error message and go to its Help page to see if you get any clues there. 

 

 

Later update: The Help page doesn't add much information for this error. You would have to use the device handbook to find out that the reason for the error is what FvM said in his post below about my suggestion that the restriction is related to the side of the device.
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Altera_Forum
Honored Contributor II
452 Views

For Cyclone III top and bottom banks, LVDS output is supported with resistor divider only, the setting is LVDS_E_3R in pin planner.

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Altera_Forum
Honored Contributor II
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Thank you, FvM, that worked. Now, I just need to figure out where to get all of those resistors from.

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Altera_Forum
Honored Contributor II
452 Views

For lower data rates, also the RSDS_E_1R one resistor solution may be used.

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Altera_Forum
Honored Contributor II
452 Views

Digikey, Arrow or Future will gladly sell you the resistors.

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