Three serial channels on Arduino UNO

I am working on an RFID reader that communicate serially with Arduino UNO on pin (2 and 3).

Also, I am displaying the information on a serial LCD connected to pins (10, and 11)

I would like to save some information at an SD card using Arduino Wifi shield, is it possible?

You need to move the LCD pins.
SD cards use SPI interface - SCK-MISO-MOSI on 13-12-11, and slave select on 10 usually, or sometimes 4. If 4, then 10 needs to be an Output for Arduino to be SPI Master, even if not being used for SPI.

You really need a Mega which has 3 spare HardwareSerial ports.

Even if you create two SoftwareSerial ports on an Uno (using suitable pins) you will have to carefully manage things so that only one of them works at any one time. Software serial is hard work for an Arduino and you may also find that it interferes with other things like SPI


Or you could add two of these chips MAX3107

Or you could add two of these chips MAX3107

I think 2 Atmega 328's would be cheaper, and two Attiny 1634's certainly would be. :slight_smile: