# References and troubleshooting

## Troubleshooting: Custom board is not visible in Arduino IDE

If the board does not show please verify that you got the board correctly added. You might also need to clear arduino cached files.

* Go into Arduino IDE preferences and get the settings directory (here : C:\Users\Nicolas\AppData\Local\Arduino15)

![](https://user-images.githubusercontent.com/2207331/213194737-5fef0680-fb88-4738-966e-cfd9349f7318.png)

* Make a backup of the folder
* Remove all subfolders.
* Restart the IDE

## Protocol reference

see protocol.h in the firmware.

## **Unlock upload**

* Send `(0xFF)(0xFF)(0xFF)(0xFF)(0xFF)(0xFF)unlock`
* Reply: `Upload unlocked\r`

Note: supporting this instruction is not mandatory to get SimHub working.

![](https://user-images.githubusercontent.com/2207331/213195090-bb314d8d-ad9c-4fad-b3b5-51fcc467d876.png)


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