Updated Appendix C: QMK Firmware Programming (markdown)

Appendix-C:-QMK-Firmware-Programming.md

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+# Important Note
+This guide is strictly for Ploopy devices that come preloaded with QMK. How do you know if your device has QMK on it? The fastest way is by plugging it in and moving the ball. If there's a two second(ish) delay before the cursor starts moving on the screen, then QMK is **NOT** present on the device. However, if there is no delay and the cursor starts moving immediately after you've plugged it in, you've got QMK on it!
+
+**You can reprogram your older Ploopy device with new QMK firmware.** The instructions for doing so are in [[Appendix D: Programming QMK on Older Ploopy Devices]].
+
+# Working with QMK
+
+The Ploopy Trackball is fairly easy to program and reprogram, thanks to the excellent work by all of the developers and maintainers of the [QMK firmware suite](https://github.com/qmk/qmk_firmware). This guide will focus specifically on flashing firmware to the Ploopy Trackball.
+
+## Before you begin
+
+If you have never used QMK before, go through [all of the steps in the QMK guide to set up your environment](https://docs.qmk.fm/#/newbs_getting_started).
+
+QMK was built for keyboards, so you'll see lots of references to code that looks like the following:
+
+`-kb <keyboard>`
+
+Whenever you see that, use the following syntax:
+
+`-kb ploopyco/trackball/rev1_005`
+
+and you'll be fine.
+
+## Building the Ploopy Trackball firmware
+
+With your terminal window open and pointed at your QMK build environment, compile the firmware with the following command:
+
+`qmk compile -kb ploopyco/trackball/rev1_005 -km via`
+
+Alternatively, you can invoke the Makefile directly with the following:
+
+`make ploopyco/trackball/rev1_005:via`
+
+If you wish, you can use the default keymap (with `qmk compile -kb ploopyco/trackball/rev1_005 -km default` or `make ploopyco/trackball/rev1_005:default`). However, the VIA keymap is particularly interesting because it allows for customization of the trackball's functions without reflashing the firmware, through the use of the convenient [VIA software package](https://github.com/the-via/releases/releases). It's incredibly handy, so definitely check it out.
+
+For more details on building QMK firmware in general, see the [QMK firmware guide](https://docs.qmk.fm/#/newbs_building_firmware).
+
+## Putting the Ploopy Trackball into bootloader mode
+
+Putting the Ploopy Trackball into bootloader mode is very easy.
+
+1. Unplug it from your computer.
+2. Hold the "forward" button. This is the button just to the right of the ball; it normally sits under your ring (fourth) finger.
+3. While holding the forward button, plug the Ploopy Trackball into your computer. If you're using QMK Toolbox, it should show up in the console. If using `dmesg`, it'll show up as an Atmel DFU device.
+
+And that's it. While plugged in this way, the Ploopy Trackball will accept new firmware.
+
+## Flashing the firmware
+
+Use your preferred method of flashing QMK firmware.
+
+- QMK Toolbox has been verified as working.
+- Using `dfu-programmer` from a terminal window has also been verified as working.
+
+For more details, see the [QMK guide](https://docs.qmk.fm/#/newbs_flashing) on flashing firmware.
+
+## And that's it!
+
+Unplug it, replug it in, and you should be good to go!
+
+Happy customizing!