Switch off the power before checking wires. If you notice smoke, a burning smell, or excessive heat, do not turn the robot on until you find the cause.
The computer cannot find the board
- Try another USB cable: some cables only support charging.
- Connect the board directly to the computer, without a USB hub.
- Reconnect USB and select the port that appears in Arduino IDE.
- Select Arduino Mega or Mega 2560. If it is missing, install Arduino AVR Boards through Boards Manager.
If the port still does not appear, contact support.
Code will not upload
First, click Verify in Arduino IDE.
If verification fails:
- No such file or directory — a library is missing. For
LittleRobot.h, install LittleRobotLibrary and Barigadam_MotionSensor. - was not declared in this scope — check the variable or command name, including capitalization.
- expected … before … — check brackets and semicolons, including on the previous line.
If verification passes but uploading fails, select the board and port again. Close other programs using that port and try another USB cable.
exit status 1 is not the cause of the error. Look for the error message above that line.
No text in Serial Monitor
- Select the connected board's port.
- Check that the code includes
Serial.print()orSerial.println(). - If the program waits at
robot.waitButtonPressRelease(), press and release the button. - If text is printed only in
setup(), open the monitor and restart the program. Remember: movement commands will run again too.
If the text is unreadable, match the monitor's baud rate to Serial.begin(...). For Serial.begin(9600), select 9600 baud.
Motors do not work
- Check the robot's power and battery charge. USB alone may not power the motors.
- With power off, check the motor wires and driver installation.
- Compare the code with the example: is
robot.begin(...)called, has the start button been pressed, and is the speed above zero?
If only one motor runs, check its wiring and channel number in the code. Make sure wheels and cables do not rub against the chassis.
If the board restarts when the motors start, switch off and check the batteries, contacts, and mechanics. Contact support if it happens again.
The robot moves incorrectly
It drifts to one side. Check the wheels and motor wiring. Equal speeds in code do not always produce a straight path — try the encoder synchronization example.
An encoder does not count. Switch off and check its cable. If readings change but have the wrong sign, compare the robot.begin(...) arguments with the lesson.
It does not stop. Switch off the power. Then check the stop command and the stop argument: with stop = 0, motors may keep running after a movement command.
Sensors do not work correctly
A line sensor cannot distinguish black from white. Check its readings in Serial Monitor, check its height, and calibrate again. Use your own measurements rather than the example values.
The robot oscillates on the line. Reduce the speed and check the left and right sensors in the code. Adjust one controller coefficient at a time, as shown in the lesson.
A sensor is not found over I²C. Switch off and check the cable. Then run the scanner from the sensor library. Test modules one at a time and match the address to the code.
Readings fluctuate. For the color sensor, check lighting and distance to the object. Keep the motion sensor still during calibration.
Line sensor lesson · Connecting sensors
Need help?
Message Barigadam on Telegram with the lesson, what is not working, and what you have tried. Send your code, the full error message, and a wiring photo. For movement problems, include a short video.