Cyclone III Configuration

Your problem statement is not clear.

Ignore the power sequencing for a start. Power-up all supplies and program the device via JTAG. Does your design work at that point? If not, have you checked the obvious, eg., does your clock pin have a clock on it.

Once you have confirmed that the FPGA actually works, then you can figure out if there is an issue with power sequencing.

You comment that firmware enables the other supplies. What firmware? Something external to the FPGA or something internal? If its internal then don't you have a fundamental design problem?

Cheers,

Dave

The other supplies are turned on by a micocontroller. Good idea to check for clock, you nailed it! I find no clock on my oscillator IC, investigating....

Rich

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The other supplies are turned on by a micocontroller.

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If the supplies are used by the Cyclone, then make sure the power-on sequence meets the requirement of the FPGA power-on-reset. If it does not, then you may have to assert nCONFIG low until all the supplies are valid.

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Good idea to check for clock, you nailed it! I find no clock on my oscillator IC, investigating....

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Check for a 180-degree rotation of the part ... darned rotationally symmetric parts ... :)

Cheers,

Dave

The original design used an oscillator with two ground pins, Vcc, and out. A replacement was used that had a standby pin, which in our design is grounded.

Ugh.

Thanks for the clue.

Rich

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The original design used an oscillator with two ground pins, Vcc, and out. A replacement was used that had a standby pin, which in our design is grounded.

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Time to break out the soldering iron :)

Cheers,

Dave