[SOLVED] EM-18 RFID Reader to PIC - Interface Confusion

Thread Starter


Joined Oct 12, 2022
I'm currently working on a project that involves connecting an EM-18 RFID Reader to a PIC microcontroller. I don't have MaxRS232. After researching online, I've come across conflicting information regarding the connection requirements, which has left me feeling a bit confused. I'm hoping to get some clarity on the matter from the knowledgeable members of this forum.

Specifically, I would appreciate some guidance on the following points:

  1. Can the Tx pin of the EM-18 RFID Reader be connected directly to the Rx pin of the PIC microcontroller, or is an interface circuit necessary?
  2. Are there any considerations or precautions I should keep in mind when connecting the EM-18 RFID Reader to a PIC microcontroller?

I greatly appreciate any insights, recommendations, or personal experiences that you can share. Your expertise will be immensely valuable in helping me proceed with this project.

EDIT : https://www.google.com/url?sa=t&sou...wQFnoECBIQAQ&usg=AOvVaw1goAaaohOlXvhFXrYnA4G6

Thank you in advance for your assistance!

Best regards,

Thread Starter


Joined Oct 12, 2022
Hi Kittu
Perhaps this link, which has a number of projects, may help.
In many cases, I see we can directly connect the Tx (transmit) pin of the EM-18 RFID Reader to an Arduino's Rx (receive) pin without the need for additional circuitry or level shifting.

It seems there is no need of external circuit.

But below link show need some external circuit

Module with external circuit




Joined Jun 5, 2013
It looks like the board has two outputs. The DB9 will be RS232 and the pin header is likely TTL. Use a scope to verify this.

Thread Starter


Joined Oct 12, 2022
I wanted to share my recent observations regarding connecting the reader directly and the solution I found to overcome a specific issue. Hopefully, this will be helpful to others facing a similar situation.

Initially, I had no trouble connecting the reader directly to the arduino mega without any intermediate components. However, when I attempted to establish a direct connection with pic I encountered difficulties in obtaining the required data. It was quite puzzling, but after some investigation and experimentation, I managed to identify a solution.

The key to resolving the problem was to incorporate two capacitors into the circuit, as indicated in the documentation. By implementing this modification, I was able to successfully connect the reader directly and obtain the desired data