10x RC522 on Arduino Megaa. Only 6-9 works

Projects Programming
1

Hey everyone,

Let me try to explain a bit about the.

I currently have 10x RC522 RFID sensors attached to an Arduino Mega. I don't have an external 3.3V power supply, so at the moment i'm using an Arduino UNO, only for supplying 5 of the sensors with 3.3V.

All the sensors is working, but only sometimes. Whenever i remove the power from the sensors and reapply it, new sensors is working. There is no connections between which sensors is working and which power supply they're connected to.

I've had up to 9 out of the 10 sensors working at the same time. Then power cycle and then only 6-8 works, including the one that wasn't working before. Another power cycle and 8-9 works.

I've tried different baudrates, with no luck. However, when a sensor is not working and i change the baudrate in the monitor, i get random characters, whenever im scanning a card on the non-working sensor.

Hope this makes any sense and someone can clarify for me what the problem might be.

Thanks

2

The tech spec for the Uno says it can only supply 50mA on the 3V3 rail. I rather suspect that five readers need more than that.

3

I see, thanks a lot.
I did have an idea that the supply would be the problem. Guess i should try to find a power supply.
Do you have any knowledge of an 3.3V power supply?

4

Outstand:
I see, thanks a lot.
I did have an idea that the supply would be the problem. Guess i should try to find a power supply.
Do you have any knowledge of an 3.3V power supply?

Btw, sometimes the problem is on the Arduino Mega as well. Is the 3.3V output only 50mA on that one as well?

5

That's what the product page says.