Timeline for What happens if I power the Arduino with both the USB and external power voltage simultaneously?
Current License: CC BY-SA 3.0
11 events
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| Nov 27, 2016 at 16:32 | comment | added | alexan_e | @Mark The only path I see for the motor to become a USB load would be through the 1117 regulator (U1) that has the USB voltage connected to its output and the motor load you describe at the input Vin. I don't know if 1117 would allow current to travel in reverse from the output to the input, I haven't tested it. | |
| Nov 26, 2016 at 23:53 | comment | added | Mark | @alexan_e If you connect a motor to the VIN pin after the barrel plug (after the diode), won't the motor become a load to the USB if the VIN source is unplugged from the barrel plug? I think I fried the voltage regulator on my arduino in this manner. | |
| May 14, 2016 at 20:49 | comment | added | sraboy | @alexan_e I appreciate the clarification! | |
| May 14, 2016 at 7:38 | comment | added | alexan_e | @sraboy Motor Shield uses the 5V line only for the logic circuitry section, the motors are powered from a separate line. You describe a situation where the motors are powered by the raw supply line Vin (7.2v battery) and the rest of the circuit from the 5V line. If the battery is depleted then the 5V of the USB with just keep powering the logic circuitry of the motor shield and Arduino, the motors would not get any power because there is no path from the 5V line (which is after the 5V regulator) to Vin (which is before the regulator). | |
| May 10, 2016 at 21:42 | comment | added | sraboy | I know this is a bit old but isn't there a danger of damaging something (your Arduino or a USB port)? For example, while plugged in to USB for serial output and using a battery pack for powering a motor shield, if your battery pack drops below 7.2V, the Arduino would try drawing all that current through USB, either destroying your board or your USB port. I know it's not the exact situation the OP was asking for but I arrived here via Google for a different situation so I think the clarification is useful. Awesome answer, by the way! | |
| S Apr 15, 2015 at 18:27 | history | suggested | Community Bot | CC BY-SA 3.0 |
corrected spelling of "USB"; changed "v" to "V" when used as an abbreviation for volt(s)
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| Apr 14, 2015 at 23:37 | review | Suggested edits | |||
| S Apr 15, 2015 at 18:27 | |||||
| Feb 25, 2015 at 15:13 | comment | added | Russell McMahon | Note that while D1 adds protection for the PWRIN pin it does not protect from eg reverse polarity on Vin. | |
| Mar 24, 2014 at 22:18 | comment | added | Ignacio Vazquez-Abrams | Note that the M7 has a nasty Vf curve; adding a few shields (or one large one) will push its Vf to 0.8V or higher. | |
| Mar 24, 2014 at 18:28 | comment | added | Ricardo | +1 Excellent answer: very detailed, precise and didactic. | |
| Mar 24, 2014 at 15:16 | history | answered | alexan_e | CC BY-SA 3.0 |