Updated Appendix C: Firmware programming (markdown)

Appendix-C:-Firmware-programming.md

@@ -55,7 +55,7 @@ In this step, we'll program the Arduino Nano with the ArduinoISP sketch so that
 
 1. Plug your Arduino Nano into your computer (via its USB mini-B port).
    - The Arduino Nano should have a few status LEDs that illuminate when it's powered on.
-   - The Ploopy Trackball will either be completely dim, or there will be a white LED that is either very dim or very bright. Any of those are normal states.
+   - You don't need the Ploopy PCBs for this step. You can put them aside for now.
 2. Fire up the Arduino IDE.
 3. Remove any capacitor between RST and GND on the Nano, and then open up the ArduinoISP sketch in Arduino IDE (in `File -> Examples -> 11.ArduinoISP -> ArduinoISP`).
 4. Upload the ArduinoISP sketch onto the Arduino Nano.
@@ -70,7 +70,8 @@ In this step, you'll use the Arduino Nano to program the Ploopy Trackball.
 2. If it's not running, start the Arduino IDE.
 3. Open the Ploopy firmware by selecting `File -> Open` and selecting `production.ino`.
 4. Ensure that a 10uF capacitor is placed between RST and GND on the Arduino Nano. (The polarity of the capacitor doesn't matter. So, if you're using an [electrolytic capacitor](https://media.rs-online.com/t_large/F5194059-01.jpg), it doesn't matter which way you plug it in.)
-5. Double-check the hookups between the Arduino Nano and the Ploopy Trackball ICSP header.
+5. Connect the Arduino Nano and the Ploopy PCBs via its ICSP header.
+   - The Ploopy Trackball will either be completely dim, or there will be a white LED that is either very dim or very bright. Any of those are normal states.
 6. In the Arduino IDE, set `Tools > Board` to `Ploopy Trackball` and `Tools > Programmer` to `Arduino as ISP`.
 7. If necessary, burn the Arduino bootloader onto the Ploopy Trackball by selecting `Tools > Burn Bootloader`.
    - You only have to do this once. Don't do this every time you reflash the microcontroller.