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Altera_Forum
Honored Contributor I
2,422 Views

Dedicated clock pin on DE2

Hi 

 

Is there a way to get a clock signal from an external device into any PLL clockin on the DE2? 

 

I've read that those clockin must be from a dedicated clock, but if I search in the manual of DE2 and the pin planer for the EP2C35F672C6(the FPGA on the DE2), those pins are already use by switches and stuff, not a single one avaible on the I/O connector. 

 

How can I set up the PLL to use one of this I/O in the 40 pin connector?, or How can I get into the PLL a signal coming from other device? 

 

Thanks a lot!
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6 Replies
Altera_Forum
Honored Contributor I
18 Views

Please review the schematic for the DE2. There are several versions of this board (DE2, DE2-70, DE2-115) 

 

On the DE2, there is an SMA on the board, it connects to pin P26 which is called CLOCK_EXT in the schematic and connects to CLK7 on the FPGA. 

 

You should be able to use that. 

 

Cheers, 

Dave
Altera_Forum
Honored Contributor I
18 Views

Thanks dwh 

My board says just DE2, so I'll use the SMA... 

Is anything else for configuration to use this for the PLL? 

I mean, I've created a PLL with the megafunction where do I tell it to use CLK7 or its just by setting the PLL clockin port to CLOCK_EXT in the pin planer? 

Thanks
Altera_Forum
Honored Contributor I
18 Views

 

--- Quote Start ---  

 

Is anything else for configuration to use this for the PLL? 

I mean, I've created a PLL with the megafunction where do I tell it to use CLK7 or its just by setting the PLL clockin port to CLOCK_EXT in the pin planer? 

 

--- Quote End ---  

You can call the clock port/net anything you like, just so long as you set the pin to P26. For example, I call it clk_sma in my top-level design file. 

 

You then connect that net name as the clock input to your PLL megafunction instance. 

 

I would recommend creating a counter and use it to blink an LED once per second. If you have the PLL configured correctly, then it'll be pretty obvious. 

 

This thread: 

 

http://www.alteraforum.com/forum/showthread.php?t=33462 

 

has an example zip file called de2_basic.zip. Download it and follow the instructions. It doesn't have a PLL in the example, but you could add it easily enough. 

 

Cheers, 

Dave
Altera_Forum
Honored Contributor I
18 Views

Thanks a lot! 

The LED idea is good for testing I guess. 

 

And thanks for the zip, I'll check it soon as I arrive to my lab
Altera_Forum
Honored Contributor I
18 Views

I can't understand what you want to say in the code word of "PLL"...? 

can you please explain? 

 

 

 

 

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Altera_Forum
Honored Contributor I
18 Views

 

--- Quote Start ---  

I can't understand what you want to say in the code word of "PLL"...? 

can you please explain? 

--- Quote End ---  

 

 

PLL = phase-locked loop 

 

http://en.wikipedia.org/wiki/pll 

 

Cheers, 

Dave
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