<div dir="ltr"><div>I agree with Andrew's idea.</div><div><br></div><div>You probably don't even need a circuit board, just nobble a cable:</div><div><br></div><div><span style="font-family:monospace,monospace">USB to board -------+------|<|---------------USB</span></div><div><span style="font-family:monospace,monospace"> |</span></div><div><span style="font-family:monospace,monospace"> +------|<|----- 5V input</span></div><div><br></div><div><br></div><div><br></div></div><br><div class="gmail_quote"><div dir="ltr">On Sun, Dec 23, 2018 at 10:11 PM Andrew Errington <<a href="mailto:erringtona@gmail.com">erringtona@gmail.com</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><div dir="auto"><div>Hi Peter,<div dir="auto"><br></div><div dir="auto">It looks like everything on the board runs at 3.3V from an on-board regulator therefore your 5V supply only needs to be nominal. How about running your power inputs into a pair of Schottky diodes? The voltage drop is small, and you could build a tiny circuit board with a micro USB socket and whatever you need for your other 5V supply as input, and a micro USB plug as output.</div><div dir="auto"><br></div><div dir="auto">Best wishes,</div><div dir="auto"><br></div><div dir="auto">Andrew</div><br><br><div class="gmail_quote"><div dir="ltr">On Sun, Dec 23, 2018, 21:32 Henri Shustak <<a href="mailto:henri.shustak@gmail.com" target="_blank">henri.shustak@gmail.com</a> wrote:<br></div><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex">Hello again,<br>
<br>
Also, as this likely pulls very little power. I will also mention the Voltaic Systems V15 feature an always on power mode. As such, it is not going to just turn off when a few milliamps are being pulled.<br>
<br>
Henri<br>
<br>
> On 23/12/2018, at 1:58 AM, Peter Ellens <<a href="mailto:ellensp@gmail.com" rel="noreferrer" target="_blank">ellensp@gmail.com</a>> wrote:<br>
> <br>
> Is this on topic? I don't know.... not sure what on topic encompasses any more!<br>
> <br>
> (maybe Mark could clarify on that)<br>
> <br>
> Details on the stm32f103 blue pill for those that don't know it. <a href="https://wiki.stm32duino.com/index.php?title=Blue_Pill" rel="noreferrer noreferrer" target="_blank">https://wiki.stm32duino.com/index.php?title=Blue_Pill</a><br>
> <br>
> I'm playing with a project that has a stm32f103 blue pill at its core. Many of you will know this board and I'm hoping that some of you will have more practical experience with this board than I.<br>
> <br>
> What I am wanting is to be able to power the board from either USB or a external 5v source, preferably being able to remove one or the other supply and it keeps going, without modifications to the blue pill board or the USB cable.<br>
> <br>
> The issue is the 5v line from the USB is directly connected to the 5v pin of the module, so you can have one or the other supply, but not both. This problem is well known, but I have not seen a solution.<br>
> <br>
> Any thoughts or ideas?<br>
> <br>
> Thanks<br>
> <br>
> Peter E<br>
> <br>
> <br>
> <br>
> <br>
> <br>
> <br>
> <br>
> <br>
> <br>
> <br>
> <br>
> <br>
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