Hardware: Arduino UNO R3 Sparkfun qwiic rfid Id-20LA

I followed this tutorial. I used the code on the website. I don't have a qwiic wire so i used standard i2c.


I ran it and nothing happens. I removed the if in the loop function to see if that is the problem and it just shows rfid 00000 so it must not be reading. Also i can see the arduino and sparkfun boards pwr led on. The read led on the sparkfun never blinks. I don't know where to look.

Also, unrelated question. If i wanted to read with this setup and after that add a bluetooth send the id tag via bluetooth on an android app. Both bluetooth and rfid would be on software serial. I saw that uno supports only 1 serial at a time. My question. Should i get an arduino Mega?

If something is unclear feel free to ask me.

  • why you ask the same question again? – Juraj May 12 '19 at 5:36
  • There are two issues here IMHO: 1) you are connecting a 3.3V powered IC to a 5V powered one. This should work wrongly. If you look at the Redboard QWIIC schematic, there is a conversion circuit between. I suggest you to use a voltage translator for I2C or use a 3.3V powered arduino board (e.g. PRO MINI 3.3V) 2) If the read led does not blink, there is a problem also with the RFID QWIIC board. Try only applying power to it, and recheck the setup (is the ID-20LA correctly connected? are you using the correct tags - 125kHz?) – frarugi87 May 21 '19 at 7:48

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