Spartan-3 configuring problem

Hi! I have spartan-3 xc3s50-vq100 device, handmade parallel cable (JTAG) and Xilinx WebPack 6.2.03i software. I'm trying to configure this device with iMPACT and I have the following problem. When "Initialize Chain" command is chosen iMPACT finds the chip but doesn't recognize it properly. Here is fragment from the log:

PROGRESS_START - Starting Operation. Identifying chain contents .... INFO:iMPACT:1588 - '1':The part does not appear to be Xilinx Part. '1': : Manufacturer's ID=Unknown, Version : 15 INFO:iMPACT:501 - '1': Added Device UNKNOWN succesfully.

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Reply to
Maciejos
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Hi, Be aware: the programming pins are powered from 2.5V (Vccaux) can your "hand made cable handle" 2.5V levels?

- looks like your TDO (output from the fpga) doesn't get propagated trhu your hand made cable (or the cable reads 2.5V High level as LOW)

from your impact logfile: INFO:iMPACT:1578 - '1': Device IDCODE :

00000000000000000000000000000000

very likely because of the 2.5v logic levels. You can (should) use the debug mode for the cable in Impact, to debug the cable and/or connections

Aurash

Maciejos wrote:

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Reply to
Aurelian Lazarut

Thanks for quick answer. I've done a test. I had disconnected TDO pin from programmer and Initialize Chain function didn't found any device (ERROR:iMPACT:585 - A problem may exist in the hardware configuration). After connecting TDO back - the same happened what was described in my first post. INFO:iMPACT:1588 - '1':The part does not appear to be Xilinx Part. '1': : Manufacturer's ID=Unknown, Version : 15 INFO:iMPACT:501 - '1': Added Device UNKNOWN succesfully.

...but 'something' was found.

I checked the cable before I connected it to my board and high level is

2.5V. I used LM2576-ADJ switching regulators (with 220uH coil and 1000uF cap) to get power supply for my chip (VCCINT 1.23, VCCAUX 2.5, VCCO 3.3). There is quartz generator 80MHz connected to GCLK input. It is driven by 5V but I used the voltage divider (2 resistors) to connect it to xc3s50. But I think that it doesn't matter what is connected to GCLK during configuration. Maybe I'm wrong. Nothing else is connected to xc3s50.

Regards.

Reply to
Maciejos

Maybe update your ISE by 6.3 + sp

Laurent www.am> Hi!

Reply to
Laurent Gauch

At this point I guess the cable has a pull up (or the floating input is seen as 1) and will read all ones (111111) you can check this in Impact debug cable menu, you can toggle TCK and sample TDO

yes probably some zeroes - again will be a good idea to probe the signal (using Impact in in debug mode) what you can try is to add a comparator and compare with 1.25V at the input, and have a pull up at the output to 3.3Vcc (or your respective cable Vcc)

not a good idea to have a switchig reg on the 2.5V (see a previous post)

looks good from the config point of view, but your issue is with the jtag cable unable to comunicate with the part, after you 'll fix this we can talk about configuration.

If you are using the PIII cable schematics from Xilinx website, be aware of the 3.3V supply (or 5V) - this cable as it is, is not directly compatible with cmos 2.5V levels you need to modify it as I mentioned above.

If Impact recognise your cable (assuming PIII cable) doesn't mean that is conecting with the JTAG tap - it means that that the loopback conections on some pins on the paralell port are recognised - thats all. (your cable has some conections directly on the connector and more, it sense the VCC cable power on a pin)

Aurash

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Reply to
Aurelian Lazarut

[cut]

Thanks again, I'll focus on my cable and will try to find some docs on debugging.

Regards.

Reply to
Maciejos

Huh? You take an 80 MHz clock through a 2:1 resistive voltage divider? Have you looked at the signal on the Spartan GCLK pin? I would expect massive attenuation of the high frequency component due to the input pin's parasitic capacitance. If you really have to do this, you will almost certainly need a compensating capacitor on the series resistor to get the signal rise time within spec. An oscillator that will run on 2.5 V would be a much better choice.

Jon

Reply to
Jon Elson

5V
Reply to
Symon

I had the similar problem. My solution is to change the C3 value to 68pF and R11 value to 47 ohm. this will solve your problem.

Reply to
pkkeng88

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