SPI – Sample of master and slave using two Arduino

Sample of SPI communication using two Arduino on S4A Programming Learning Board :

Arduino’s SPI master code (mirror)

Arduino’s SPI slave code (mirror)


How it works:

When at master board is pressed button attached at pin 2 (zero level), it is immediately received by slave and lits led at pin 3 on. Afterwards, master is reading slave and updates its led at pin 3. Pressing again button at pin 2 at master side lits led at pin3 off at slave side and, afterwards, master updates its own pin 3.


Modbus RTU on RS485 using Arduino and PyQt

Bill of materials:

Arduino Nano

S4A Programming Learning Board (pdf)

USB to RS485 Converter

RS485 Converter Module Board For Arduino

Arduino source code (version for RS485 module)

Program source code in pyQt (Python + Qt)


Arduino         S4A PLB (P1)      RS485 module
  GND               P1-1              GND
   5V               P1-10             VCC
    5               P1-4              DE
    6               P1-3              RE
    7               P1-2              RO
    4               P1-5              DI
                                      A / D+
                                      B / D-