Pi not booting with rfid plugged in

Hi. My raspberry pi 4 boots fine without the rfid header plugged in. If it powers up with the header plugged in, the green activity light is very dim and it won’t boot. If I unplug the header, it proceeds to boot and I can plug in the header anytime after and the rfid reader works fine. Any thoughts?

I would double check your power supply and make sure it is up to task. Also, sometimes even when rated properly the wiring on a power supply can be cheap and inadequate.

Likewise check the cable quality if you’re powered off a USB or USB adapter.

We are using the canakit that was supplied with the pi. I’ve tried a couple of them. The weird thing is that it worked fine for a day or two, then started this flaky behavior. I’ve ordered a different cable

Hi there, me again. I ordered the official Raspberry Pi power supply, and the pi still won’t boot with the RFID header plugged in. I must draw too much current at startup. I have 3 of these rfid devices and 3 Pi 4’s. All (don’t) work the same, no boot unless I pull the header off and then put it on with the Pi booting. Not something I am comfortable with, and not practical either. Does the connector to the changed devices need a terminating resistor or something? I’m not using it, so it is empty. Any ideas to make this boot up? I tried the RFID header on a Pi 3 and 3B. They boot, but the RFID won’t read the tags.

The RFID shield will not work with Pi 4. The Pi had some issue with 3.3V supply and we had to add external 3.3V supply on our other shields.

If you are using on Pi 3 check the serial port name.


Shoot. The description said it would work with a Pi4. https://store.ncd.io/product/raspberry-pi-2-and-3-rfid-receiver-and-i2c-adapter/ . The Pi 3 (not B model) works as far as the boot sequence and will detect the supplied ID token and card, but doesn’t detect the smaller RFID tags we are using to band birds. (https://eccel.co.uk/product/2-3mm-em4102-pit-bird-tag-green/). I guess I’ll have to look elsewhere for readers. Thanks for the help.