DSO Shell: Micro USB mod

This is a very simple modification, you just need 3 resistors and a micro usb connector breakout board.

And now, we have USB live, serial  output  for the moment, exactly like a bluepill.

That frees the RX/TX pins, we have something much better instead of basic serial.

Might be a good idea to use them for the rotary encoder at a later point.


The mod (with the usual craftmanship), it is really simple to do.
I superglued 2 acrylic nuts to the board, so that i can screw the micro usb on them.
It needs more mechanical strength (yes, it will be hotglue)


The schematic :


Comments

  1. UnknownAugust 22, 2019 at 5:29 PM

    This mod should work with the JYETech firmware too, right?

    ReplyDelete
  2. meanXAugust 23, 2019 at 1:52 AM

    From a hardware point of view : yes
    But i dont think the JYETECH firmware is initializing USB at all, so you'll probably see nothing if you connect to a PC/MAC.

    With my firmware , you'll see a com port (*and* DFU when it boots to do firmware upgrade over usb).

    The USB ID is something like 1eaf:004

    ReplyDelete
  3. UnknownAugust 30, 2019 at 2:50 PM

    I was thinking of using the same micro usb jack for both power (connect vcc to a boost converter or to a tp4056) and for serial. Do you think there should be any problem with that?

    Also, did you try to get rid of the 7805/7905, i.e., take V+ directly from 5V and V- directly from the 7660? (is USB 5V stable enough for that?)

    Thanks for all the information!

    ReplyDelete
  4. meanXAugust 30, 2019 at 10:13 PM


    The USB specs allow for +-10 % on the USB i.e. between 4.5 and 5.5 V. If you dont use the 7805/7905 you are back to the zener, the calibration will change with usb voltage / temperature


    In short, it may "kind of work", but the accuracy will suffer

    If you want to get rid of the battery, what you can do, is just boost the signal from usb VBUS to say 9V with a DC/DC converter (they are small and cheap) + some filtering caps

    It will add a bit of noise, but that works

    The unit consumes ~ 150 mA , so even with loss and the boost converter you'll be fine with the 500 mV delivered by USB

    ReplyDelete

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