Atom Lite only powers via USB-C but not 5V from pin header

  • I got the Atom RS485 kit and my RS485 endpoint provides +12V DC on the orange header which I want to use to power the Atom.

    I measure +13V at the DC12V input pin. Without the Atom Lite connected, I measure 4.84V at the 5V pin header on the base.

    However, when I connect both, I cannot reach the Atom. Note that even with the Atom Lite in place, I still measure a fixed +13V at the DC12V input pin, hence I do not believe the source is unable to supply sufficient current (otherwise the voltage would drop).

    However, if I power the Atom Lite via USB-C instead, everything works.

    I thought already the base is broken, hence I ordered an additional base but unfortunately same.

    Why does the Atom Lite fail to power from the 5V from the pin header?

  • Hello @expjwt

    according to the description the M5Atom can be powered from the 12 V.

    A DC/DC voltage regulator chip is integrated in the ATOM RS-485, which can directly convert the 12V voltage of RS485 to 5V to supply power for M5ATOM, avoiding the trouble of using a separate power supply.

    BTW: The 5 V on the header pin is connected to the 5 V on the Groove port. What voltage do you measure between 5 V and GND on the Groove port?