Troubleshooting ---LEONARDO R3 Development Board

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Leonardo R3 can’t be recognized by computer


  • Whether driver is installed or not
  • Right-click “Computer”>“Property”>“Device Manager”, and check the driver“under Other Devices”. You need to install driver if driver is not founded.
  • If device manager doesn’t show device.
  • Check micro USB port of development board and computer.
  • Change another USB.
  • Change another computer to test board.

If none of them works, maybe the development board has something wrong. Just contact our after sales

Compilation error on Leonardo

In general, IDE will prompt error code“avrdude: stk500_getsync(): not in sync: resp=0x00”if there is compilation error

sync:resp = 0x00 is a common response which means that“Atmega” chip of Arduino board doesn’t work. Once this situation happens, you can adopt the following instructions to solve problems.

  • Ensure that pin 0 and 1(serial port) of Arduino board are not connected (expansion board included)
  • Ensure that you choose correct COM port and development board Press rest button and upload code
  • Disconnect and reconnect Arduino to PC
  • Reboot Arduino IDE

If the above methods don’t work, try different Arduino boards on PC or test this board on another PC. This can help you to figure out how to tackle problems. If there is something wrong with Arduino IDE, just re-install Arduino IDE; if it is Arduino board, try to refresh the circuit board with Arduino firmware.
If neither of them works, feel free to contact our customer service

Can’t run code when power on Arduino board

Arduino board can’t run the code uploaded to development board, when plugged in power.


  • Firstly check the code if it doesn’t run when Arduino board is plugged in power.
  • When Arduino board starts working, boot loader will monitor computer and send new code to Arduino board.
  • If Arduino board doesn’t receive new code, after a while, boot loader will overtime and run the code uploaded to Arduino board. However, neither of the boot loader and the previous code uploaded will overtime and start if your code sends serial data in a few minutes.
  • If Arduino board starts working, you need to find a way to delay serial data to Arduino board. In addition, you will use external compiler to upload code to Arduino board if the adjustments effect the program.
  • If the uploaded code doesn’t run but return to Arduino flashing code(indicator on Pin 13 flashes), you will use boot loader to burn Arduino board because the boot loader of circuit may be damaged.

No response after uploading code

  • Ensure that you choose the correct COM port and development board.
  • Code exceeds the capacity of circuit board.
  • There will be errors when using a power supply with a relatively large ripple, therefore, ensure stable power.

Sketch is too Large

There will be errors if sketch is larger than Leonardo development board’s flash memory. For instance, the flash memory of Leonardo is 32kb, and boot loader of Arduino uses 4KB. However, Arduino will send warnings if the code more than 32kb is uploaded.


To solve the above problem, you have to find a way to occupy less space, as shown below:

  • Try to use integer data type rather than floating point in any case.
  • Try to use“const”qualifier when stating variable
  • Only necessary library included. Try to use the most important library of lightweight version.
  • Improve code. Technical can help you short code and simplify algorithm.
  • Transfer code to another board, like Arduino Mega which has larger flash memory.