0122-21 LED Snake EMO-R8

Example Projects > 0122 UniPi 1.1 > 0122-21 LED Snake EMO-R8

LED snake on UniPi with EMO-R-8

The relays of UniPi expansion board EMO-R-8 are controlled to create an illusion of a "snake" moving from RELAY1 to RELAY8 and then cycle to RELAY1. The speed of movement is selected by the UniPi inputs I01 through I06.

The BIS binary signal generators produce pulses at various frequencies. The UniPi inputs determine which of these signals is used to move the snake bit-by-bit.

Note that this is only a demonstration algorithm. If run for prolonged periods it significantly reduces the lifetime of the relays!.

Timing of the project

The algorithm runs each 5 milliseconds (0.005 s). See the EXEC function block,
tick x ntick0 = 0.005 x 1 = 0.005


  • REXYGEN Runtime Core and RPiDrv modules must be installed and running on the Raspberry Pi.
  • I2C bus must be enabled on the Raspberry Pi.

Running the example

  • The *exec.mdl file is the project main file, open it with REXYGEN Studio.
  • Compile and download the project to the target device.
  • Activate one of the inputs to move the snake.


Additional information

  • More info about the UniPi board can be found at unipi.technology.
  • Raspberry Pi is a trademark of the Raspberry Pi Foundation.
  • Visit the REXYGEN webpage for more information about the example projects and developing advanced automation and control solutions using REXYGEN.