How to safely power Notecarrier AF?

Hi,

the Notecarrier AF has USB and 2 JST, and the Feather board (e.g. ESP32) has USB and JST. Which of these can / should be used to power the assembled dev kit? And is it safe to connect both USB ports at once? (e.g. to get debug output from the Feather and use the Blues debug terminal).

Kind regards,
Thomas

Hey @tamberg, great question! You absolutely can plug USB cables into both the AF and the ESP32 at the same time. I do this all the time during development for exactly the reason you describe: to connect directly to the Notecard over USB serial and push firmware updates to the ESP32. Both devices will draw their power directly from those ports, but both are connected to a common ground, so won’t interfere when simultaneously connected.

As for the JST connectors, we recommend powering your project through the JST port on the Notecarrier-AF and not from the ESP32 or another Feather that includes a LiPo. You’re not at risk of ruining either device by powering through the Feather JST in terms of what we have tested, but since the Notecarrier includes additional power circuitry and reverse polarity protection, you’re better off going through the JST on the Notecarrier itself.

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