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Altera_Forum
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16 years ago

Cyclone III not configuring

I have a 144 pin cyclone 3 that I'm trying to get working in a board design I've done. It is not configuring. I can see the TCK on the oscilloscope but no TDO data comes back from the FPGA.

The nConfig and nStatus pins are both high and the CONF_DONE flag is low. I went through the altera trouble shooter but with no luck.

One issue is that a ground pin and VCCA pin were shorted together when I first put the chip on the board. It got really hot when I turned it on and the voltage levels were screwed up. I'm not sure if I fried the chip. CONF_DONE is pulled high with a 10k resistor so the fact that it is low made me think the chip was still good. I've ordered some more chips and I'll try them out if I figure something else out first. Thanks.

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  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    Yeah, I have 0 ohm resistors there. I was thinking of putting inductors there as a way to try to control the rise time of the voltages. They are 0603 resistors.

    They have a low power rating which I was concerned about, but so far just trying to load in a really simple program I haven't seen any indication that they are failing. I have some ferrite beads with a 4 A rating that I can put there if it turns out to be a problem.
  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    I don't think just having VCCA at ground should hurt anything. I would suspect that the center pad isn't making contact. The center pad is the ground return for the core. The ground pins are only the port driver and PLL grounds.

    I've soldered other parts with a ground slug and it takes a LOT of heat to get the board and plane up to temperature. If you're hand stuffing boards the hole is a good idea. If you are going to stuff more boards I would only solder 2 pins to hold the part in place and then solder the ground. With only two pins soldered you can verify that the ground slug is soldered in place by trying to wiggle the part around. Once you know the ground is soldered then do the rest of the pins.
  • Altera_Forum's avatar
    Altera_Forum
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    16 years ago

    It's working! Thanks for everyone's help. I think it was definitely the bottom slug. I did a whole new board and put a lot of paste on the bottom. I didn't initially realize how much clearance there was between the board and the pad, so I think I didn't used enough paste the first time. Thanks again.