Here we go again! For a very simple project i used a MAX7032S. Suggested pullup an pulldown are used at jtag pins, connections kept as short as possible and large ground path as well. Only way to download POF file to my handwired prototype is to fit few picos capacitors across Clk, TMS and ground. I would not like to fit this capacitor on the final PCB!! Any suggestions ???? Thanks in advance Alf P.S. Using BYTEBLASTER II

Hello Half, Normally you must only use a PullUp on TDI,TDO and TMS and a PullDown on TCK With a Usb Blaster you don't have any problem to program your EPLD. If you want to be sure You can insert a resistance (value apr. 26.1O) between Blaster and the component. In my opinion this does nothing in your case because you have only one component.

I think handwired may be a keyword for understanding the problems. Generally, from the JTAG signal, only TCK is edge sensitive, thus if you manage to produce a ringing TCK at the CPLD pin (e. g. by wiring inductances), the JTAG interface may see false TCK edges and fail. A small capacitor at TCK may sometimes help to get a clean TCK signal, but an appropriate wiring would be a better and more reliable way, I think. With a good PCB wiring, you shouldn't need capacitors.

Agree with FvM, just have a look at the schematics of the various Altera Development kits (available in download on the Altera website) and consider that implementation of the JTAG interface. You won't have problems!

Thanks guys My thinking is the same, i'll be sure just with the arrival of the final PCB I'll keep you informed about it. Thank you for the moment. Alf

every thing looks fine with the final PCB

Jtag problem | Altera Community

14 Replies

Altera_Forum
Honored Contributor
17 years ago
Did you try the JTAG Chain Debugger in Quartus Programmer to narrow down the error analysis?
Altera_Forum
Honored Contributor
17 years ago
I checked it. But "JTAG configuration invalid" on instantce manager and "No device in selected" on JTAG Chain Configuration window are display.
If click Auto detect in programmer, it's display "Unable to scan device chain. Can't scan JTAG chain". Did I incorrect setting in menu? But I think that the settings in menu are simple. Why...???? Help me!!!
Altera_Forum
Honored Contributor
17 years ago
JTAG debugger works also with no device detected. But it most likely won't give additional information. It can be used however, for some JTAG hardware checks.
Altera_Forum
Honored Contributor
17 years ago
Hi, FvM
All of Vcc connecting JTAG pullup resistor and the device are 5V in my board.
For pogramming the device, does Vcc connecting JTAG pullup resistor change to 12V?
Vcc of the device is 5V.

Thank you.

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Jtag problem

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