I've got an Leonardo board, it seems to be official, in that it has the Arduino branding and Made In Italy on the bottom.
However I cannot get anything to run with external power supply. Everything when powered via the USB from the computer runs fine. As soon as I use any sort of external power, and I've tried both the barrel jack with 4x AA batteries, 6x AA batteries, 9v square battery and a Shield with 2x 3.7v lithium batteries - it turns on but doesn't do anything - the USB device doesn't even appear to the computer at all unless I pull the external power out again.
Is this a faulty board? Do I need to change the jumper arrangement on the board so it'll run with external power?
asked Jan 11, 2019 at 13:54
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2And what "jumper arrangement" are you on about? There's no jumpers on a Leonardo.Majenko– Majenko2019年01月11日 14:19:46 +00:00Commented Jan 11, 2019 at 14:19
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1The ICSP section - I thought it might have something to do with it. I guess i've just got a dud board then. It's a Leonardo R3 by the way.Danny Shepherd– Danny Shepherd2019年01月11日 14:29:15 +00:00Commented Jan 11, 2019 at 14:29
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1I think key to my sketch is that it's working over USB-HID - it's that connection which is never made when powering externally - it doesn't appear to the computer at all. As soon as I pull the external power it connects to the computer as a HID device.Danny Shepherd– Danny Shepherd2019年01月11日 14:46:29 +00:00Commented Jan 11, 2019 at 14:46
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1I am testing it and everything is working as it should be. Can you give more information? Do you know how old the leonardo board is and which bootloader is on it? What kind of power supply? What is your sketch?Jot– Jot2019年01月11日 14:57:31 +00:00Commented Jan 11, 2019 at 14:57
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14xAA won't work as the VIN voltage must be greater than 6.6V to get precedence over the USB voltage. Did you check the polarity? The middle contact is positive, the surrounding contact is GND (negative).Pylon– Pylon2019年01月11日 18:08:14 +00:00Commented Jan 11, 2019 at 18:08