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Module programming

A general tutorial common for all modules. For specific features and functions read module documentation.

Accessing specific module

Module API can be accessed by declaring it's class. It will work right away, without a need for initialization. Multiple instances can be created.
If module is not physically connected, all functions calls will be ignored.

Module11 module; // Declare use of distance sensor [11]
Module11 module2(25151); // Declare use of distance sensor [11] with serial 25151
ModuleXX - each module hash class implementation name of Module + number.
module - a variable name of Module11. Can be any (sensor, controller, lineReader, ...). This instance is used to call module functions.
(25151) - if there are multiple modules with same number - serial is used to specify exact one. Using instance module2 will send commands to specific module only. Otherwise - all connected [11] modules will receive a command. Check X4.module on how to get serial.

General functions

Module functionality is objective oriented. Format module.<feature>.<function>() is used to group all it's features and call functions.
module - instance of specific module.
<feature> - features that are supported by module (distance, rgb, ...).
<function> - functionality that is available for each feature (get, set, color, ...).

Communicating with module
// Read distance from sensor
int distance = module.distance.get();
// Set RGB color to green
module.rgb.color(0, 255, 0);


Using event functionality
// Distance module instance
Module11 sensor;
// Event function of distance feature
void distanceEvent() {
  // Check if it's a "distance" feature event
  if (sensor.distance.isEvent()) {
      // Read cached distance data from event (non-blocking)
      int distance = sensor.distance.getCm(); // Takes no time to execute
void setup() {
  // Register event function for Distance module
  // Enable events for distance parameter
  sensor.distance.event(); // When value is changed
void loop() {
  // Read distance by sending request and waiting for response (blocking)
  int distance = sensor.distance.getCm(); // Takes ~1ms to execute
  // Wait 1 seconds

Reading with functions like module.distance.get() works by blocking code until response from module is received (same as I2C). For non-blocking read or subscribe functionality - event system is used. Blocking function calls are executed very fast (around ~1ms. As do I2C). So it's fine to use them most of the times. It's much easier than managing events.

Event system works by registering specific module parameter and it will be sent when value is changed or in time intervals.


Register event function for specified feature. Will be called when new data is available.
Event data can be received simply by using functions from registered <feature>. Data is cached and won't initiate read request, but must be called inside registered function.
function - event function name (distanceEvent).

(state) module.<feature>.isEvent()

Check if event is received. Used inside event function. Useful if same function is registered for multiple features.
state - is event received [true:false]


Start event for specified feature. Will be triggered when value is changed.


Start events for specified feature. Will be triggered at inverval rate (milliseconds).
Example: setting event(100) will call registered event function every 100ms.
interval - event update time (milliseconds). 0 - disable event.


Call event handler only once. Won't start broadcasting.

Multiple modules example

Simple code example to show usage of Line Follower + Potentiometer modules and interaction between them.
• Knob A - controls LED position on Line Follower
• Knob B - controls RGB brightness
• Knob C - controls RGB color

// Declare modules
Module14 line; // Line follower module
Module15 pot;  // Potentiometer module
// Start program
void setup() {
  // Empty
// Loop program
void loop() {
  // Read Potentiometer module knob positions
  int knobA = pot.knobA.get();
  int knobB = pot.knobB.get();
  int knobC = pot.knobC.get();
  // Display Knob A position on Line Follower module;
    map(knobA, 0, 255, 0, 7) // map [0:255] -> [0:7]
  // Change RoboBoard X4 RGB color depending on Knob B, C positions
    knobB, knobC, 255-knobC, 0 // alpha, reg, green, blue
  // Delay 20 milliseconds