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  • @user7114 - lots of insertions. The nice thing about the USB connectors is that all the sprung contacts are in the socket, so you really can get away with something very simple for the plug. If you look at those tiny WiFi/bluetooth USB donges, they do something very similar as well.

    @DrAzzy / @Joakim Thanks for the feedback about the pins...

    • Yes, those 4 at the end are USB. The reasoning was that you could then solder a pin header socket on and push the board directly onto a PC motherboard, but you can just surface mount it on the normal USB connector anyway. I've already pulled them out of the next prototype.
    • If I dropped the extra pins but put pads for an SMD pin header on the other side, would that work for you? Then it's tiny, but still has the pins if you need them. I feel like if I'm going to make it small, I should make it impressively small :)
    • As for WiFi/Ethernet I'll try and get the SPI ordering right - I'm very limited though because there's so little space for tracking. I'm toying with the idea of tweaking Espruino to allow use of different pins for Wifi/Ethernet/filesystem (which I should do anyway) and then maybe also allowing software SPI - in which case you could just attach the modules wherever you wanted.

    I'd be interested to hear your thoughts on the power supply. I've kept the same as the original Espruino (minus the fuse), but I think it's overkill. Effectively it means you have pins for:

    • USB voltage in (maybe just on the USB connector)
    • Battery voltage in (and JST battery connector pads on the rear)
    • Bat/USB voltage out (this is Bat on the Espruino board)
    • 3.3v out

    Personally I think that's too much, and a little confusing... I think a lot of people expect a little board like this to just have Vin, and maybe 3.3v out.

    I guess one cool side effect is that I've connected the FET to a GPIO, so if you're running Espruino from USB you actually get one powered output for free, which you could use for speakers/relays/etc.

    • Re: USB - makes sense.
    • Re: SMD pin header - what do you mean by "SMD Pin Header"? Are we talking the ones that are like normal pinheader with the ends bent 90 degrees so you can surface mount it? Or some sort of higher density connector? In the latter case, connector selection (to get something that is readily available and easy to find) would be important to making it useful. I had a wonderful awful idea - what if the pads were right along the end, at 0.1" spacing... then you could take a 2-row pinheader, put it on the edge, and solder it to the pads (so one row was on the top, the other on the bottom) - this'd be kinda ghetto though.
    • FS/Network anywhere without having to recompile the firmware would be nice.
    • Re: Power... I'm not sure how you could change the power supply without degrading the usefulness of board - you need to be able to power it off of USB, and safely connect it to USB when it's also got external power on it (for in-place development/debugging/monitoring/etc of an espruino in something with an external power supply) - so those voltages are going to have to exist somewhere, even if not broken out anywhere other than the USB and JST headers. You certainly can't leave the 3.3v pins - if someone's using a voltage higher than 5.x volts, they'd have to wire up a regulator or stepdown to get power for connected devices, which'd be no fun.

    On the topic of power, I don't suppose there's space for pads for a MAX155x (SOT-23-5)? You expressed interest in this last time it was brought up, and for the kind of portable applications that an espruino the size of a flash drive seems good for, being able to add automatic battery charging when plugged into USB by dropping on two parts (the header and the MAX155x) would be sweet...


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