Xilinx Boards and Kits

[kirantherock]

Hi there!

I have just acquired a Xilinx SP601 Eval board and have received the ISE software ver. 11.3 with the same. I am going through the In-depth tutorial of the ISE but am stuck at one point. In the 'Creating a DCM Module' section, I need to use the Clocking wizard. In that when I select FPGA Features and Design > Clocking, I cannot find the clocking option for the Spartan 6 board in the software.

Could someone help me as to what values are needed to be changes so that I can use this module on my Spartan 6 board. Can I directly use the FPGA Features and Design > Clocking > Clocking Wizard. ?? If so, what values do I need to change?

Regards,

Jack

[joelby]

Yes, just use Clocking Wizard.

You'll need to correctly set the input clock frequency based on the SP601 clock you wish to use (I think you've got a couple to choose from). The SP601 manual will tell you what the clocks are, which pins they're present on, and if they're single-ended or differential.

[kirantherock]

Thanks a lot there joelby!
I now need to generate a simple square signal of 100 Mhz using the FPGA. I tried looking for any simple programs but to no avail!!!
Any help???

Regards,
Jack

[joelby · Accepted solution]

How far did you get with the clocking generator? It will do everything you want, other than deciding what to do with the 100 MHz signal - that's where you come in.

If you need to forward it to an external pin, use an ODDR2 clock forwarding scheme. Have a look in the language templates for details about ODDR2.

Depending on your needs, you may also be able to just use the 200 MHz system clock with a divider to produce a 100 MHz output.

[kirantherock]

Wooohooo!!!! I've done it!!!

Thank you thank you thank you Joelby!

[joelby]

Excellent! I'm glad you sorted it out :)

[kirantherock]

I have managed to generate the required signal as instructed and have got the output both at the SMA connector as well as the LEDs on the SP601 board (the code is attached). Now I have an FMC XM105 debug card and I want to select one of the pins on the debug card as my output. I wanted to get the output on the LEDs on the FMC board.

I checked the Pin connections and the LED corresponds to the following pin connections:

FMC connector J17 pin G37 corresponds to the LED DS1 on the board.

Checking the FMC LPC Pin Connections of the SP601 board, I found out that this pin (G37) corresponds to the (N9) pin on the FPGA board.

Now when I connect my output to the (N9) pin on the board, I should be getting the output on the FMC card, right? But that's not the case! I am not getting any output on the FMC board. The XM105 card is working properly (I hope), since on Power Good LEDs i.e. DS5, DS6, DS7 are on.

Are there some more steps to configure the XM105 board? I even tried changing the Jumper setting J4 on the SP601 board (in which it says to include FMC) but then I got an error while downloading the program on the board. The ISE iMPACT window gave an error "Program Failed" in that case.

What do I do??

[joelby]

J4 is used to route the JTAG chain via the FMC LPC port. It's only necessary if your FMC card contains additional JTAG devices that you want to put in the chain.

Pin N9 looks like it's correct. Are you sure the LED is not working correctly? Have you probed it with a fast oscilloscope? (at least 100 MHz, since you're just checking for the existence a 100 MHz signal)

If you're toggling an LED at 100 MHz with a 50% duty cycle, perhaps you just can't see it lighting up. Start small, with a 1 Hz pulse, or just assign the LED output to '1' or something.

[kirantherock]

Hi there again Joel!
I've been trying many different permutations and combinations with my signal and have been steadily increasing the frequency from 20MHz up to 400MHz.
The only problem is that the signal starts degrading as the frequency increases. Up until 20MHz, I get a proper square wave with a 50% duty cycle. Thereafter the wave starts getting more and more noisier. After 100 MHz I cant see any square wave anymore, it simply becomes a sine wave. Why is that??
Also, how do I counter that effect? I need a clean signal at least until 100MHz wherein I get a clean square wave without much percievable noise.

I am taking the output at Pin H18 of the SP601 which corresponds to the SMACLK_N on to the oscilloscope. Have attached my program for reference.

Regards,

Jack

[eteam00]

Are you using an oscilloscope to probe your signal?

If you want to measure a 100MHz digital signal with a 'scope, the scope and probes should be rated for at least 350MHz bandidth.  A 1GHz scope will give you more accurate measurements than a 350MHz scope, but 350MHz should be (barely) adequate.

A 100MHz scope (and probes) is entirely inadequate for measuring or displaying amplitude, risetime, shape (e.g. ringing or reflections) or duty cycle of a 100MHz digital signal.

-- Bob Elkind