4DSP Support Forum
Products => FMC Products => FMC122, FMC125, FMC126 => Topic started by: zhangxiang on November 09, 2013, 07:49 AM
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I have calibrated fmc126 yet . but i still have some question about fmc126
1:should i calibrate fmc126 everytime i use it to sample signal?
2:what is the use of calibration_results.h ? the ml605_fmc126_cal.bit just samples the signal of 600.59mhz? how should i sample other signals what i want sample in fact ?
3:my sample-frequency is changable (1G~5G), the calibration reference design seems just for 5G. IF i change the frequency, does [size=78%]the calibration reference design work?[/size][size=78%] [/size]
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HI
1)
calibration should be done for each individual FMC126 for a specific temperature range and specific sample frequency. The calibration results can be re-used and programmed directly to the ADC registers next time you will use the FMC126.
2)
the .h file holds the values that were found during the calibration process and can be used to program the ADC registers directly. The calibration requires a specific frequency, once calibrated you use the ADC for any frequency you like. You cannot change the sample frequency without re-calibrating.
3)
That is correct the calibration package is specifically tuned to 5GHz sampling frequency. The same principles can be applied for other sample frequencies, but you need to investigate for each frequency what to change in the software to make sure the calibration will work correctly.
Best regards,
Erik
Best regards,
Erik
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I want use the calibration reference design to calibrate the fmc126 for one-channel mode with sample-frecequency 2.5G.
So I change "samplingFrequencyForGainMHz" from 1250 to 1250/2,"clockFrequenctForPhaseMhz" to 2500.0f/2,and fmc12x_clocktree.cpp .
But when I run the fmc126_calibration.exe , it always tells me that training status is busy ,and Could not initialize FMC12x! It makes me confuse!
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HI
the FPGA interface to the ADC is tuned to work at 1250 MHz. Lowering this interface frequency too much will require changes to this interface.
the FMC126 uses 4 ADC devices that run at 1250 MHz each. For 5 Gsps 4 ADCs are used to sample 1 signal. for 2.5 Gsps I suggest to set the ADC in 2 channel mode and to only offload one of the two channels. this keeps the FPGA interface frequency at 1250 MHz.
[/size][size=78%]Best regards,[/size]
[/size][size=78%]Erik [/size]
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if i use the external sample frequency about 4G in one-channel mode, can I use the reference design to calibrate it? according to what you have said , it seems that the sample frequency can't be too low ?
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Dear Sir,
Running at 4G require changing software/firmware settings and most likely re simulation of the firmware. But yeah it can be done with a modified reference design.
Best Regards,
Arnaud
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I am confused about the sync signal. according to software ,the sync is created by cpld. it meas (no sync) -(SYNC_FROM_FPGA) -(no sync). If it's ok ,the signal SYNC_FROM_FPGA must be set 1. But according to what I detect with .cdc , it is set 0 .Is it ok?
and have you try to sample in 4G one-channel-mode ?
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SYNC_FROM_FPGA is not connected on ML605. It is pulled up to 'High' on the FMC126. The software switches between SYNC_FROM_FPGA '1' and NO_SYNC '0' creating a pulse obviously.
No we haven't tried 1 channel @4G but our calibration package provide one channel mode at @5G which is faster, changing this reference to sample at 4G is possible.
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Dear Sir,
could you let us know what company you purchased the calibration package from?
Thank you,
Pierrick
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It's E-element.
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According to the document ,I think if I set FMC126 in one-channel mode and give a sync signal to ev10aq190 ,the four adcs will sample signal synchronous . if I want make the sample data in a smooth curve ,what i need to do is just setting offset,gain,phase registers in appropriate values .But now ,the datas sampled show me that the four ads are not synchronous .It seems there are several delay periods among four ads.What's problem?
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Dear Sir,
According to our records you have not purchased the calibration package therefor we cannot provide you with any technical support, sorry for that.
Feel free to contact sales@4dsp.com or E-Element in order to clear that up!
Best Regards,
Arnaud
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I have just bought FMC126 form this 4DSP.To be honest I am a very beginner for all this.
And I am hearing about this calibration package.I searched in my folders if this file exist.
But I couldn't find it there.
Would you mind what is this package use for and is it necessary!!
If so where should I contact.
Thank you
Dipen
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Dear Dipen,
The FMC126 calibration package contains all the element you need in order to use the FMC126 in one (5Gsps) or two (2.5Gsps) channels.
The default FMC126 reference design brings the FMC126 in four (1.25Gsps) channel mode and the four channels are not synchronous in digital and analog domain.
You can contact sales@4dsp.com in order to get the pricing/availability of the calibration package.
Best Regards,
Arnaud
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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.