Hello, I am a beginer and have a basic question. My project implemented on FPGA board (which is Spartan3E-1600 Microblaze Development Kit) includes ADC and is supposed to do some digital signal processing of an analog RF signal from 'outside world'. How I can input an analog signal to my FPGA?
Hi,
I don't know this board do you have a link to it description?
If it is a parallel ADC you generally need to feed your ADC with your sampling clock and then you get your sample from the adc every clock cycle. An easy way to check this is to put a probe on the ADC input using chipscope and put a signal generator at the input of your ADC and then you look with your probe the signal you receive, if you inputed a a sin wave you should get a sin wave in the probe.
alexis
My problem is that I do not understand how to establish a connection between an output of signal generator (which is RF connector) and an input of ADC which is one of FPGA pins as they are physically incompatible. (As I understand one of FPGA's pins has to be assigned as an input of FPGA-based ADC.) I just guess that there are should be something else between an analog source and FPGA board, isn't it? and I would like to learn what it is.
If the voltage is in the range of the allowed input voltage for your ADC (take a look at the data sheet of your kit) and the frequency is not too high (I guess the ADC doesn't convert more than 1 MSPS), try a crocodile clip. Don't forget to attach the ground, too.
Usually the FPGA doesn't have an integrated ADC, but you have to assign and program it to access the external ADC.
-- Frank Buss, fb@frank-buss.de http://www.frank-buss.de, http://www.it4-systems.de
ems.de
Thank you. Using a crocodile clip should work indeed but I look for something more robust and permanent.
What are you talking about? There are no ADCs in Spartan-3E! You can make a delta-sigma one yourself
/Mikhail
Do you have the manual for the board? Hint: it's Xilinx p/n UG257.
The section "Analog Capture Circuit" starts on Page 75 of That Fine Document.
Header J7, which is a bog standard 0.1"-center pin strip, is the input to the two ADCs.
You'll probably have to make a cable or adapter so you can use those pins. If you are incapable of making such an adapter, you probably shouldn't be messing around with FPGAs.
-a
Thank you very much, it's very helpful indeed. By the way, it's a shame that I have not noticed section 'Analog Capture Circuit' myself..
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