How Many Software Serial Ports can you have on an Arduino UNO R3

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1

Hey Everybody,

I am currently using an Arduino UNO R3. I am using the hardware serial port (PINS 0 and 1) for programming and debugging using the serial monitor.

I am using a SoftwareSerial port (PINS 2 and 3) for transmitting and receiving data from a 4DSystems uLCD-70DT. This works great…UNTIL

Until I added on more SoftwareSerial port (PINS A2 and A3) for receiving GPS data from a GPS receiver. Do I need to “end()” the use of one SoftwareSerial port prior to “begin()” another.

Or can I have the 1 hardware serial port and 2 SoftwareSerial ports opened simultaneously???

Or do i need to get something like an Arduino Mega 2560 R3?

I am using the Adafruit_GPS library. Does this have an adverse affect on the SoftwareSerial port?

TIA,

–Neal

2

Given the design of softserial, you can only use 1 full functional software serial port (receive and transmit). Next to that you can have multiple softserial transmit-only ports. The Softserial port that is added last in the sketch will have the full functionality only. The MEGA2560 could indeed be a solution for you.

3

Dear Paul,

Thank you for the suggestion. I have the 2560 on order and I should be able to sort this out very soon after I take delivery. I will confirm this when I hook everything up.

I am basically trying to use 4 hardware serial ports:

  1. basic programming of board and serial monitor

  2. Adafruit Ultimate GPS receiver

  3. 4DSystems microLCD-70DT display GPS coordinates and other information

  4. xBee transmitter to send commands from microLCD-70DT display to to a remote device

TIA,

–Neal

4

Ok. So I purchase an Arduino Mega 2560 and this solved my serial port issue. I now have enough hardware serial ports for the serial monitor, 4DSystems uLCD, GPS receiver, and xBee transceiver.

Thank you Paul for the information.

–Neal