Troubleshooting Guide

First check : mod installation and configuration

Go to your KSP/GameData folder. You should see a KerbalSimpit folder if SimPit is installed (else, install it with CKAN).

Open the configuration file KSP/GameData/KerbalSimpit/PluginData/Settings.cfg

The line PortName = COM3 should be updated with the correct port number. It should be identical to the one used with the Arduino IDE on Windows. On a Linux or a Mac, the USB port ID will look like /dev/cu.usbmodem401 OR /dev/ttyUSBO.

The line Verbose = False should be replaced by Verbose = True to increase the level of detail written in the logs. It is assumed for this guide that Verbose is set to True.

Launch KSP and check in the logs that you can see the following lines (either by opening the in-game console with Alt+F12 or by opening the file KSP/KSP.log :

  • KerbalSimpit Has put a message into the console!

  • KerbalSimpit: Settings loaded.

  • KerbalSimpit: Using serial polling thread for XXX where XXX is your port name (on Windows, it should be the same as the one set in the config file).

Make sure that you installed the SimPit Arduino library in the library folder of Arduino. You should see the File/Examples a category called Kerbal Sim Pit.

First example : receiving information from KSP

The next step is to check the connection from KSP to the controler. For this, we will use the provided example called KerbalSimpitAltitudeTrigger

Open the example with the Arduino IDE, compile it and upload it to the Arduino. Make sure that KSP is not launched when you upload the code. You should see the built-in led turned off.

Then launch KSP and go to the launchpad with a rocket (for instance the 2nd Training called Basic Flight).

Before taking off, you should see the folowing in the KSP.log file :

  • The log line KerbalSimpit: Opened COM3 meaning that the connection was started on KSP side.

  • The log line ACK received on port COM3. Handshake complete, Arduino library version '1.3.0 meaning that the connection was established between KSP and the controler.

  • The log line KerbalSimpit: Serial port 0 subscribing to channel 24 meaning that the controler requested an update of the altitude of the craft.

You should also see the built-in LED turned on when the connection is established.

Then activate the SAS and launch your craft straight up. As soon as its altitude is above 500m, you should see the built-in LED turned off.

After the fligth, exit KSP and go check in your log for any error related to KSP. If no error are found and if you saw the LED turning off when going higher than 500m, congratulation. Your controler can receive information from KSP.

Second example : sending information to KSP

For this test, we will use the provided example called KerbalSimpitStageDemo. The objective is to launch your rocket based on an input from the controler. You will need to use a button connected to the pin 2 of the Arduino on one side and on the ground to the other side (see this example from Arduino). You can also just plug a wire from the pin 2 to the GND pin to simulate a push on the button if you don’t have one.

Start like the previous example :

  • Compile and upload the code while KSP is closed

  • Launch KSP and open the Basic Flight training

  • Check for the connection in the KSP log (note : there will be no log indicating a subscription from the controler to a channel).

Then activate the button (or insert the wire). The rocket should take off.

After the fligth, exit KSP and go check in your log for any error related to KSP. If no error are found and your rocket took off, congratulation !! You are now ready to start your own controler.

Common mistakes

At one point, my controler stopped working

Please check for any error in the KSP log. If at any point an error occured, the SimPit mod will stop and no information can be shared with the controler, thus giving the impression that the controler is not working.

What does an error look like in the KSP log

Here is an example.

[EXC 20:48:03.683] IOException: A device attached to the system is not functioning.

System.IO.Ports.WinSerialStream.ReportIOError (System.String optional_arg) (at <376e8c39bbab4f1193a569c8dbe4305c>:0) System.IO.Ports.WinSerialStream.Write (System.Byte[] buffer, System.Int32 offset, System.Int32 count) (at <376e8c39bbab4f1193a569c8dbe4305c>:0) System.IO.Ports.SerialPort.Write (System.Byte[] buffer, System.Int32 offset, System.Int32 count) (at <376e8c39bbab4f1193a569c8dbe4305c>:0) (wrapper remoting-invoke-with-check) System.IO.Ports.SerialPort.Write(byte[],int,int) KerbalSimpit.Serial.KSPSerialPort.<SerialWriteQueueRunner>b__29_0 () (at <d23bc766ee8645b4813da6de1d115a35>:0) KerbalSimpit.Serial.KSPSerialPort.SerialWriteQueueRunner () (at <d23bc766ee8645b4813da6de1d115a35>:0) System.Threading.ThreadHelper.ThreadStart_Context (System.Object state) (at <ad04dee02e7e4a85a1299c7ee81c79f6>:0) System.Threading.ExecutionContext.RunInternal (System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, System.Object state, System.Boolean preserveSyncCtx) (at <ad04dee02e7e4a85a1299c7ee81c79f6>:0) System.Threading.ExecutionContext.Run (System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, System.Object state, System.Boolean preserveSyncCtx) (at <ad04dee02e7e4a85a1299c7ee81c79f6>:0) System.Threading.ExecutionContext.Run (System.Threading.ExecutionContext executionContext, System.Threading.ContextCallback callback, System.Object state) (at <ad04dee02e7e4a85a1299c7ee81c79f6>:0) System.Threading.ThreadHelper.ThreadStart () (at <ad04dee02e7e4a85a1299c7ee81c79f6>:0) UnityEngine.UnhandledExceptionHandler:<RegisterUECatcher>m__0(Object, UnhandledExceptionEventArgs)

When I add more functionalities to my controller, it starts to behave strangely (messages lost, corrupted, etc.)

It is probable that the Arduino serial buffer size is too small given the time between each call to simpit.update and the number of messages sent. You can test this by displaying mySimpit.packetDroppedNbr. If it is non-zero, it means that some messages were corruped.

To fix it, you have several solutions :

  • Increase the serial buffer size in HardwareSerial.h. To find the right file to modify, see here : https://forum.arduino.cc/t/solved-serial-buffer-size/581828/10. There should be a log line in KSP.log indicating the buffer size when an Arduino connect. The default is 64 bytes and the recommandation is at least 256.

  • Reduce the number of channels you subscribe to

  • Call simpit.update more frequently. For instance if you have a controller with several parts, you can call simpit.update between each part update instead of updating all the parts and only then call simpit.update.

To test that this is not the root cause of your issue, you can use the KerbalSimpitStressTest example. Subscribe to all the channels you want to use, and test several values of delay to see if some messages are lost. Then try on you controller to measure what is the delay between two calls to simpit.update and compare the two values.

I have some issues with custom action groups (CAG) when using Action Group Extended (AGExt)

There is some know issues when using AGExt.

For stock CAG (below 10), AGExt seems to disregard activating empty CAG. This means that the controller cannot activate any CAG between 1-10 even when the those CAGs can be activated via keyboard since the game allow to activate empty CAG.

There is also an issue that in some cases the toggling of a CAG is not working when the CAG content was not set at launch but is modified during flight. The root cause might be the content of the stock CAG not being the same as the AGExt CAG with the same number. Simpit is only using the AGExt CAG, not the stock one, when AGExt is installed. In this case, you should check (and modify) CAG content using AGExt GUI only, not the stock one, to avoid this issue.

For non-stock CAG (11 and above), there seem to be an issue with empty CAGs. AGExt allow to activate empty CAG, and the value of the CAG seems to be shared between several vessels (behavior not consistent with stock CAG). Meaning that if craft A and B have an empty CAG 11, it can be toggled on any craft and when switching craft, the value is kept instead of being tied to the vessel. If the CAG is populated on both craft, switching from one to the other works as expected.

There is no known workaround currently, the issue seems to be in the way AGExt handle those edgecases. AGExt should not be installed when not needed.