RFID and power question

Using Arduino Motors, Mechanics, Power and CNC
1

Hi,

I'm using:

(1) x Elegoo Mega 2560 R3
(1) x RC522 RFID module

I've connected the RFID module to a voltage step down module which is connected to an external PSU. I've noticed that the LED on the RFID module is illuminated when the Arduino Mega is connected to my laptop via USB and the external PSU is switched off. Why is this? The power as I understand it should only be coming from the external source. The RFID board is not longer reading and I'm wondering if there's been too much voltage passed through it and its blown.

Anyone have any ideas?

Thank you.

DN

1 Like
2

That is ghost power coming from the logic connections. Awoid that situation, or make that time as short possible.

3

How would I do that? Is it likely my RFID reader is damaged?

4

Don't let that be the situation for more time then necessary.
Else use a step up converter from the 5 volt. I assume that reader doesn't need that much current.

5

I already have a step down converter which gives 3.3V to the RFID reader. Looks like the problem is that I have a PSU in addition to this. So when I was uploading code the power from the USB produced the ghost voltage and in addition to the main power supply it broke the reader. So my solution is switch off the main power when uploading code :wink:

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