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Newbie
Newbie
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Registered: ‎07-06-2020

KC705 200MHz system clocks?

Hi Guys, 

I think this is a really dumb issue. 

I tried the simplest thing ever, to route the 200 MHz differential clocks

NET "clk_200M_p" LOC = AD12; # 200 MHz
NET "clk_200M_n" LOC = AD11; #

directly to the two GPIO SMA connectors at

NET "test_outA" LOC = Y23; # GPIO-SMA, J13.1
NET "test_outB" LOC = Y24; # GPIO-SMA, J14.1

For whatever reason, my 500MHz scope just does not show up anything of these two 200MHz at the two SMA connectors.

I don't believe my KC705 board is defective, since I tested the 8 GPIO LEDs, and they are working at least.

NET "GPIO_LED(0)" LOC = AB8;
NET "GPIO_LED(1)" LOC = AA8;
NET "GPIO_LED(2)" LOC = AC9;
NET "GPIO_LED(3)" LOC = AB9;
NET "GPIO_LED(4)" LOC = AE26;
NET "GPIO_LED(5)" LOC = G19;
NET "GPIO_LED(6)" LOC = E18;
NET "GPIO_LED(7)" LOC = F16;

 

Is there any comment? I did quite a lot of programming with ML506/ML507/ML605/SP605, and had never ever got this strange issue.

 

Many thanks in advance.

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1 Reply
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Registered: ‎06-21-2017

What IO Standard is the output?  If it is LVDS, you need a termination resistor across the _p and _n signals.  Do you have one?  Most, if not all differential signal standards require some termination scheme.  What is the bandwidth of your scope probe?