Docs/coredump info (#57)

* Core dump info documentation

* Add image of coredump

* Add image to show FileZilla process

---------

Co-authored-by: Justin Babilino <[email protected]>

CoreDumping.md

@@ -0,0 +1,52 @@
+# Coredumps for WPILibC projects
+
+Using an Ubuntu PC connected to the robot's network, you can analyze coredumps that happen when the robot code crashes.
+
+## Enabling coredumps
+
+FTP to the robot using [WPILib's tutorial on FileZilla](https://docs.wpilib.org/en/stable/docs/software/roborio-info/roborio-ftp.html),
+but replace `lvuser` with `admin` so we can overwrite system files.
+
+We have to edit `/usr/local/natinst/etc/init.d/lvrt-wrapper` on the RIO, but commands like `vim` and `nano` don't work on ssh since the
+OS is pretty barebones. So, we'll use FTP instead.
+
+Download `/usr/local/natinst/etc/init.d/lvrt-wrapper` to your PC.
+
+Open your local copy in a text editor. The `ulimit` line needs to be changed to allow full coredumps to be saved:
+
+```
+# stack size
+ulimit -s 256
+
+# core file size
+# uncomment to enable core dumps
+#ulimit -c unlimited
+```
+
+```
+# stack size
+#ulimit -s 256
+
+# core file size
+# uncomment to enable core dumps
+ulimit -c unlimited
+```
+
+Upload your copy back to the robot and overwrite the original.
+
+Open the driverstation and reboot the RIO:
+
+![Driverstation UI](https://mililanirobotics.gitbooks.io/frc-electrical-bible/content/Driver_Station/diagnostics.png)
+
+## Retrieving the coredump
+
+Now, any time your code crashes, the file `/var/local/natinst/log/core_dump.!home!lvuser!frcUserProgram` will be created.
+Don't let the RIO lose power after it happens or you may lose the coredump.
+
+![Core Dump Retrieval](https://github.com/TripleHelixProgramming/ChargedUp/blob/docs/coredump-info/CoreDumpImage.png?raw=true)
+
+Use FileZilla to copy that file from the RIO. It may take a minute or two to download.
+
+## Analyzing the coredump
+
+--Coming soon--