The SwitchMachineTest sketch runs on an Arduino-class microcontroller, and communicates via I²C with one or more Arduino-type microcontrollers running the SwitchMachineController sketch. The controller sketch is written to run on an Adafruit Pro Trinket or ItsyBitsy 32u4, and supports up to four switch machines, numbered 0 through 3. For this sketch, all switch machines on all controllers, if connected, are operated together. You can find a sample track layout with two turnouts in the extras directory here.

The test sketch toggles the controllers' outputs periodically between their 'main' and 'diverging' settings. The sketch also supports two momentary normally-open pushbuttons connected between GPIO pins and ground.

• pin 11: Sends a RESET command to the switch machine controllers.
• pin 12: Sends a REFRESH command to the switch machine controllers.

More information about the commands recognized by the switch machine controller can be found in the SwitchMachineController sketch's README file at https://github.com/twrackers/SwitchMachineController-sketches/blob/main/README.md

The test setup uses a STEMTera™, a breadboard with an Arduino UNO compatible processor inside, as a test processor. Mounted in the breadboard space on top is a pair of Adafruit Pro Trinket processors, each programmed with the SwitchMachineController sketch. There is also one or two momentary normally-open pushbuttons between two GPIO pins on the STEMTera and a ground connection.

The STEMTera's I²C pins SDA and SCL are connected to the Pro Trinkets' SDA and SCL pins as well, forming an I²C bus with the STEMTera as the central and the Pro Trinkets as peripherals. Each Pro Trinket uses 3 GPIO pins to set its peripheral I²C address to a value between 0x30 and 0x37. For this setup, I used 0x30 and 0x31.

LEDs are connected to some of the 3-pin output channels of the SwitchMachineController processors, which are connected as [blue, red, green] to monitor [enable, red, black] signals respectively for each channel.

The SwitchMachineTest runs in a loop where it sends commands via I²C to switch all connected controllers' channels to "diverging" state for 1 second, then back to "main" state for 2 seconds, then repeats indefinitely. By pushing either of the connected pushbuttons, "reset" and "refresh" commands can also be sent to the controllers.

Instructions for installing the SwitchMachineTest sketch can be found in file INSTALL.md in this repository at https://github.com/twrackers/SwitchMachineTest-sketches/blob/main/INSTALL.md.

The SwitchMachineTest sketch uses the following libraries.

• Wire library, part of the Arduino IDE distribution
• FIFO library, https://github.com/twrackers/FIFO-library
• OneShot library, https://github.com/twrackers/OneShot-library
• Pulse library, https://github.com/twrackers/Pulse-library
• Pulser library, https://github.com/twrackers/Pulser-library
• PushButton library, https://github.com/twrackers/PushButton-library
• StateMachine library, https://github.com/twrackers/StateMachine-library