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Altera_Forum
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11 years ago

problem with JTAG configuration cyclone III

Hi, I am using cyclone III, epc3c10k. I have a problem of configuration from JTAG using usb blaster. Where I try to programming from quartus the JTAG can’t work. I connected the ncomfig, ...
Altera_Forum's avatar
Altera_Forum
Icon for Honored Contributor rankHonored Contributor
11 years ago

YES the lack of ground pad will prevent detection via JTAG!

I had the same problem that this guy had, the circuitboard guy forgot to put a pad down and couldn't connect to jtag.

I had troubles drilling a hole (went too deep thru the board into the chip!) , plus in a 6 layer board how do you not short some of the layers when you solder the wire in the hole? Cant get enough heat down there anyway.

So I got another board and Solderd a wire to the tiny tiny corner of the chip where the leadframe is molded. (See leadframe diagram)

Each corner has a tiny bit of metal that is connected to the bottom ground pad.

I measured on an ohmmeter that the ground pad is NOT connected to any ground pins but is connected to the leadframe metal corners.

Anyway its extremely fragile but now it connects via JTAG!!!!!!!!!!!! I don't get it but that ground pad must be different than any other ground on the chip......I might try to get a less fragile connection by dremelling out some of the epoxy corners to expose more of the leadframe so I have more to solder to.