Power WB55 via 5V Pin and have USB connected at the same time

[XG_it]

Hi,

is it safe to interface a WB55 via USB and simultaneously power it via the 5V pin from some external batteries? The battery-voltage I use is limited to 5V. I have some concerns about bricking some electronics due to multiple grounding. Are there some safety measures in place against it?

[TDK]

With multiple power supplies you need to ensure supplies do not power each other. That can be done by using a schottky diode between the supply and the VCC rail, or some other such isolation.

There are no issues with multiple grounds.

[XG_it]

What I forgot to mention:grinning_face_with_sweat: I'm using the WB55 on a nucleo board. See the schematic here. It has some diodes on it protecting the 5V pin. Do you think this is sufficient? I'm more of a programmer I can barely read these schematics. I'm surprised I even understand that there are diodes on it. But no schottky diodes I think :thinking_face:.

[AScha.3]

>is it safe to interface a WB55 via USB and simultaneously power it via the 5V pin

Which USB ? from st-link usb there is a power switch, to enable/disable connection.

And JP3 is there, to let you connect the source, you want.

"USB and simultaneously power it via the 5V pin " is no good idea , set the jumper on JP3 to the source you use, thats simple and safe.

Why you want "USB and simultaneously power it via the 5V pin " ?