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Altera_Forum's avatar
Altera_Forum
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16 years ago

EP2 won't AS configure, nCONFIG stuck lo

EP2C5Q208 will not AS configure itself. Circuit is exactly as Fig. 13-7, page 13-20 in Cyclone2 Device Handbook, Vol. 1 for a single device. Configuration device is EPCS4. (Using USB Blaster Quartus II v9.1 seems to program and verify the EPCS4 successfully with the .pof file.) I followed the few suggestions of the FPGA Configuration Troubleshooter. I know MSEL[] should be 00 for EPCS4, but configuration doesn't get far along enough to matter, at least I don't think so.

Setup:

All VCCIO = 3.3V.

All VCCINT = 1.2V.

MSEL[] = 10.

All pull-ups are 10k for AS configuration (per Fig. 13-7).

nCE pull-down is 10k. (Measures 0.03Vdc when powered, so seems low enough)

All pull-ups and pull-down for the JTAG connections are 1k (per Fig. 13-22)

All connections are confirmed with ohmmeter

Each VCCIO and VCCINT pin is bypassed with .1uF.

3.3V and 1.2V derived with LDO regulators and bypassed with >20uF each.

Symptoms:

VCCINT comes up in <50 us.

nCONFIG says low forever.

nSTATUS rises quickly with 1.2V and stays high.

nCSO rises to 3.0V with 1.2V then after 95 ms jumps abruptly to 3.3V and stays there.

Second problem:

This board is also wired for JTAG configuration as per Fig. 13-22, page 13-55, same document. The EP2C5 will not configure with JTAG either (filetype used was the .sof).

All EP2C5 pins are beautifully soldered as inspected with a microscope. This is the first board of this project and my first experience with FPGAs.

Please help.

5 Replies

  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    The fact that you are unable to configure through JTAG is a big red flag. Can you ID the cyclone device with the USB blaster or does that fail as well? If you can ID the device, but the programming fails, it may be due to a fault on nCONFIG. but if you can no ID the device at all, That usually is a power supply issue.

    It looks like you have already checked your VCC IO's and VCCINT levels, but also make sure your VCCPLL's are ok On the Cyclone 2 device these should be filtered versions of the VCCINT 1.2V, but if you have mis-stuffed components, you may have an open there preventing configuration to start.

    Pete

    nCONFIG should have a pull-up on it. Make sure it's not shorted to ground somehow, This would prevent AS configuration, but not JTAG device id.

    Let me know if you are able to r
  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    Thanks Pete,

    I don't exactly know what you mean by "ID the device". If you mean to use the "auto detect", then pressing this button in the Programmer does not seem to do anything. The single line entry in the programmer still shows the .sof "File" name, to the right of that EP2C5Q208 "Device", to the right of that the "Checksum" value, to the right of that FFFFFFFF "Usercode", etc.

    The PLL VCCA and VCCD power terminals are filtered exactly as recommended: 10uF before and after a ferrite bead to these power terminals located real close to the FPGA. Plenty of bypassing. Solid 1.18Vdc measured, just like VCCINT terminals.

    I find no short on nCONFIG pin. There's 10.8k ohms to ground and 9.7k ohms to VCCIO with the power off. When power's on, there's 0.006Vdc on nCONFIG and 0.000Vdc to a nearby ground. What I mean by this is that the nCONFIG pin is not a dead short to ground.

    Help me with the "ID the device" and what do you recommend next?

    Thanks a lot!
  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    For the device ID, in JTAG mode, when you have no .sof loaded, you should be able to do a "Auto Detect" like you assumed, and should added the EP2C5 device to the list.

    IE delete the EP2C5 from the list, so you have just a empty screen, then hit the auto detect, and it will find the EP2C5 but not have a .SOF associated with it. If this works, then at least the device is alive. If not, check to make sure the TDI/TDO pins aren't swapped. Also noise or poor termination may be present on TCLK causing issues.

    Since you have the MSEL's set for AS, you should be able to probe the clock, CS and data pins on the configuration device and see activity. If you see no activity, it's not trying. I believe nCONFIG must be high to work, so you may try to add a stronger pull-up to VCCIO to determine if you can force activity on the configuration pins.

    Pete
  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    The problem as described at post# 1 was resolved by observing I had two of the configuration signals connected together that should not have been. After fixing this, however, Active Serial Configuration Stage does complete, i.e. CONFIG_DONE never goes high.

    Also, I still have the problem that programming the EP2C5 with JTAG does not work. The Programmer message states:

    Info: Configuration succeeded -- 1 device(s) configured

    but the FPGA does not do anything programmed. I will start another thread describing the latest trouble.
  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    Hi Greg..

    It sounds like you may have an issue with the layout on nCONFIG. If this pin is stuck low, JTAG programming would be able to complete, but it would instantly try to restart AS configuration. So your design would never run.

    Pete