4DSP Support Forum

Products => FMC Products => FMC150 => Topic started by: fmcuser on August 27, 2014, 11:25 PM

Title: LVDS-to-LVCMOS conversion
Post by: fmcuser on August 27, 2014, 11:25 PM

The ADC data coming from the FMC150 through LPC is LVDS.
I want to change them to be single-ended.
Can you tell me the VHDL codes to realize this?

Title: Re: LVDS-to-LVCMOS conversion
Post by: iklink on August 28, 2014, 09:30 AM

Dear,


What is the sample rate that you want to use for the FMC150? The datasheet of the ADC notes that the maximum recommended sample rate for LVCMOS is 210MSPS and even at that rate it is not guaranteed that the data will be error free.


Best regards,
Ingmar van Klink
4DSP

Title: Re: LVDS-to-LVCMOS conversion
Post by: fmcuser on August 28, 2014, 10:07 AM

The sampling rate is less than 100 MHz.
I used "ibufds" (http://www.cs.indiana.edu/hmg/le/project-home/xilinx/ise_13.2/ISE_DS/ISE/doc/usenglish/isehelp/7series/libs_le_ibufds.htm) to change the differential signals (LVDS25) to the single-ended signal.
Do you think this is okay?

Title: Re: LVDS-to-LVCMOS conversion
Post by: iklink on August 28, 2014, 10:55 AM

Hello,


You should use IBUF for single-ended signals, the IBUFDS you are using is for differential signals. You should also modify the IO standard constraint in the .ucf to:
 NET "<signal name>" IOSTANDARD = LVCMOS18;


Best regards,
Ingmar

Title: Re: LVDS-to-LVCMOS conversion
Post by: arnaudNL on September 03, 2014, 04:42 AM

Dear Sir,


I believe you received the information you needed.


I will proceed with closing this topic in 24 hours withing extra feedback from your side.


Feel free to open any new topic any time you need to do so.


Best Regards,
Arnaud

Title: Re: LVDS-to-LVCMOS conversion
Post by: arnaudNL on September 04, 2014, 08:22 AM

This topic is being closed because the issue is considered as resolved by 4DSP. Feel free to create a new topic for any further inquiries.