Hello all!
I consider myself a bit conservative when it comes to double/triple checking things before implementation, but I'm finding conflicting information on the supply of the Arduino's. I've always played it safe when uploading new/revised sketches to my Arduino by removing the external power supply before connecting a laptop via USB. I've read in some topics in this forum that this is not necessary, but I enjoy the comfort of knowing I'm not about to make a smoke machine in completing the extra step.
Now, I have a new project using a well regulated external power supply that will be switched on/off as required by the user. It will also have a full time USB connection so the user can manipulate the sketch via Node Red.
Does anyone have experience using an external power supply, and a desktop USB connection where either can be powered ON/OFF? Are there any issues with this? HAAALP!
In principle it should work OK, but it's possible that the Arduino resets as the external PSU is switched on or off. This is somewhat unpredictable and depends on the startup/shutdown behavior of the PSU and whatever else is part of your system.
Do you have a schematic for this particular project?
Thanks for the response. I don't have a schematic for the project. I'm not overly concerned about the inputs/outputs of the Arduino, but moreso the Arduino itself being connected to two separate power supplies that can be switched off at any moment. Further, is it safe to assume the ground of the USB connection will keep the two supplies at the same potential, am I overthinking this?
The GND of the USB as such won't do anything by itself, but as long as it's connected to the PSU's GND (not 'safety earth'!) they will indeed be at the same potential.
Hi,
looking at the schematic of the Due board you see the following:
If there is an external PSU connected to the Due board then the onboard DCDC converter will provide 5V and the 5V from USB will be disconnected.
If the external PSU will be switched off then the 5V from USB is automatically switched on and power from USB (0.5 A) needs to be sufficient to support the board and every shield connected to the board.
If there is only the Due board then there is no problem. USB can easily support the board. But with shields supported from the 5V and 3.3V pins of the Due there might be problems. Be aware of this.
This topic was automatically closed 180 days after the last reply. New replies are no longer allowed.