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Espruino is a JavaScript interpreter for low-power Microcontrollers. This site is both a support community for Espruino and a place to share what you are working on.
@allObjects
Diodes have a behavior like this: you run them in reverse, they block. Your run them in forward mode, they let the power pass but
take a tollof it. The toll is 0.2...0.8, depending on the circumstances (SEE https://learn.sparkfun.com/tutorials/diodes/real-diode-characteristics). To protect also your button cell from powering the USB, we need a 2nd diode:1 Attachment