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can't download program into EP2C5 via jtag

Altera_Forum
Honored Contributor II
‎07-02-2011 03:14 AM
1,643 Views

i can't download program into EP2C5 via jtag,so i test it use Quartus II tool named jtag chain debugger ,Quartus II know the device is EP2C5 TMS TCK TDO is ok ,but there is a Fork on TDI,then i use oscilloscope to test Circuit, 

i found the wave of TMS TCK TDO is good ,but the TDI is not good , 

the wave of TDI is in the attachment  

high level is 3.3V ,that right,but the low level is 1.68V (the half of 3.3),not 0V 

,can anyone tell me why?
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Altera_Forum
Honored Contributor II
‎07-04-2011 08:29 AM
355 Views

What kind of pull-up do you have on TDI? Isn't it too small?

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Altera_Forum
Honored Contributor II
‎07-04-2011 08:54 AM
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the pull-up is 1k 0603 they are ame on TCK and other

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Altera_Forum
Honored Contributor II
‎07-04-2011 09:09 AM
355 Views

okay... it could be the jtag cable that has a bad driver then... can you test it on another board?

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