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PostPosted: Sun Jan 04, 2015 5:44 am
by acapola
Is there a document about the board ? In particular I am looking for the following:
- power supply options (is it safe to provide 5V externally and then connect the USB port ? What about the debug header... that sort of things)
- schematic with part names so that I can find the datasheets

Re: doc/schematic

PostPosted: Tue Jan 06, 2015 11:52 am
by Carl-SolderSplash

Yes, have emailed them to you.

You can provide 5v's externally via a pin, the debug header is a standard arm cortex jtag connection for use with an LPClink or similar.


Re: doc/schematic

PostPosted: Tue Jan 06, 2015 1:08 pm
by acapola
Hi Carl,

Thanks very much for the schematic, that will be helpful. So the debug header is not providing power supply, good.
Now for USB and the +5V pin, the board just short them together. If the user connect both the board will not mind, which is good, but I am afraid that either the USB or the +5V source is going to suffer.
Maybe I am being a bit paranoid, or even plain wrong (long time I did not design any PCB) but as it is, I would say: user must connect USB or +5V power supply but not both. Such restriction may be annoying for application which rely on the USB port to connect a computer for diagnostic, setup and so on...
Please comment on that, if you can guarantee that there is no problem then it is all fine, if you can't, you should make sure users now about that kind of stuff!

Best regards,

Re: doc/schematic

PostPosted: Wed Jan 07, 2015 3:51 pm
by Carl-SolderSplash
Applying your own source of 5v's is safe to do, there is no power switch though. So when you connect the USB your 5v supply will be connected (via an inductor) to the USB 5v's

The only downsides that I can see are :
- That 5v's will be supplied to the VBUS input which is generally used to indicated that USB is present, but It doesn't have to be used.
- Your 5v's *could* be used by the USB hub and it's devices, if your 5v's was slightly higher than its. That depends on the hubs protection.