Question about power supply


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Hello everyone, 

First off, I'd like to introduce myself, as I'm new to the papilio community. I am Andy.

I had a question about the papilio one power supply. I uploaded a standard zpuino to the papilio, running simple code that sends a line to the serial port every second. After letting this code run for about a minute I noticed that the 2.5v regulator in the power supply was burning hot. Too hot to touch in fact! I have nothing connected to the board, and nothing is shorted out (eg the board is sitting on a plastic table while running). Is this normal? It makes me extremely nervous that its going to blow, and take the spartan with it. :( Any feedback or input is much appreciated.  Thanks in advance!


-Andy V

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Hello Andy,


It is normal with the Papilio One design for the linear voltage regulators to get hot when a design that uses a lot of power is loaded. ZPUino pushes the limits of the Spartan3e chip so it pulls a lot of power. One of the downsides of linear voltage regulators is that they do heat up, its the reason that the Papilio Pro changed to a more efficient switching regulator. No need to worry, lots of people are running zpuino on the Papilio One without problems, just excess heat.



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Thanks for the reply, Jack!

This puts my mind at ease. I guess that I should have realized that the ZPUino put such a load on the fpga. I thought simple sketch = low power draw (still gotta get used to the differences between a micro and an fpga)  :) .Anyway, I'm very excited to be a part of the community, and I'm loving the papilio! Now I've just gotta wait until the due is released. (Unfortunately I missed the kickstarter).



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ZPUino does not have any idle instructions, so power is a bit high. This is due to the internal block RAMs on the FPGA - they do eat a lot of power, and since ZPU is a stack processor, almost all instructions need to use the block RAM.


XThunderCore will have instructions for power control, and those will give a huge power advantage over ZPU. First release is scheduled for about Christmas. It will be compatible with IDE and standard libraries, as one would expect.



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