B4R Tutorial Connecting two Arduinos with rSoftwareSerial library


With the rSoftwareSerial library you can turn regular pins to serial ports. This is useful as the hardware serial is used by the IDE during development.

There are some limitations to the supported pins: https://www.arduino.cc/en/Reference/softwareSerial

As an example, the following program should run on two boards. When you press on the connected button, the on-board led on the other board will turn on.

Sub Process_Globals
   Public Serial1 As Serial
   Private astream As AsyncStreams
   Private led13 As Pin
   Private btn As Pin
   Private softserial As SoftwareSerial
End Sub

Private Sub AppStart
   led13.Initialize(13, led13.MODE_OUTPUT)
   softserial.Initialize(57600, 10, 11)
   astream.Initialize(softserial.Stream, "astream_newdata", Null)
   btn.Initialize(btn.A0, btn.MODE_INPUT_PULLUP)
End Sub

Sub Btn_StateChanged (State As Boolean)
   Dim b As Byte
   If State Then b = 1 Else b = 0
   astream.Write(Array As Byte(b))
End Sub

Sub astream_NewData (Buffer() As Byte)
   Dim state As Boolean = Buffer(0) = 1 'state will be true if buffer(0) is 1.
End Sub

The library is attached (it will be included in the next update).


  • rSoftwareSerial.zip
    1.7 KB · Views: 1,362


Licensed User
Longtime User
Success with the Uno :)
The two softserial channels are defined as usual and I'm changing the serial.listening method to listen to only one at a time.
I have measured the time to get answers form the DFplayer and found it is less then 30 millies, and the query to it is every 2 seconds, so the rest of the time is free to listen to the phone and get instructions.
Transmitting is not limited so it is done when necessary.

Eme Fibonacci

Well-Known Member
Licensed User
Longtime User
softserial.Initialize(57600, 10, 11) on both Arduinos?


softserial.Initialize (57600, 10, 11) 'For arduino1
softserial.Initialize (57600, 11, 10) 'For arduino2