SX 52 Protoboard questions

Electronegativity

Hi guys, I want to run the SX52 protoboard at 3.3V from a PC power supply.

Is there any reason I couldn't hook the 3.3V line right to Vdd?

Also, I want to supply an external clock signal from an FPGA.
Can I just put that signal into the 2 outside contacts of the 3-pin Xtal socket?

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I wonder if this wire is hot...

LoopyByteloose

I would take a close look at the schematics.

It would be better to remove the +5volt regulator or at least to be sure to disable it [noparse][[/noparse]via OFF switch]. Another alternative is to replace it with a pin compatible +3.3volt regulator. [noparse][[/noparse]But in your case, that seems redundant and unnecessary]

After all, there is some possilbility that backflow of current through the existing regulator might cause problems with the 3.3volt.

The oscillator has two inputs - OSC1 and OSC2. I believe that you can input an external clock via OSC1 and appropriately adjusting FUSE selection in the software. Read the PDF on the SX52 about external oscillator configuration. The biggest difficulty might be that this addition extends the circuitry and exposes you to EMI problems, but you have an access.

Since the switch has 3 modes - OFF, ON with out Servos, and ON with Servos - take some time and test what happens in the OFF condition. The board has internal layers which apparently include the power switching.

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"When all think alike, no one is thinking very much.' - Walter Lippmann (1889-1974)

······································································ Warm regards,····· G. Herzog [noparse][[/noparse]·黃鶴 ]·in Taiwan

Electronegativity

Thanks Kramer, I was wondering about that switch.

I thought these ST LMxxxx type regulators shut themselves off if there was a reverse current, but I guess I'll just pull it off the board to make sure there's no weird feedback.

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I wonder if this wire is hot...