Thanks to my colleague Piki from northern Germany and thanks to Dotsha747’s open source FMC PCB and hardware guidance I have been able to complete the first Flight Management Computer (FMC).
It uses a Rasperry Pi 3B instead of the Rasperry Pi Zero recommended by Dotsha747 since I want to use a wired LAN connection throughout the cockpit instead of WLAN. The Rasperry Pi 3B has more computing power and is further able to operate X11 and my custom OpenGC version very elegantly. The lightplates and keycaps are from OpenCockpits. They fit almost perfectly to the PCB of Dotsha747. The only problem was the EXEC light which I had to drill manually into the lightplate.
The 5″ screen comes with a VGA display driver is connected via a VGA-to-HDMI adapter to the Rasperry Pi and the keys are backlighted. The unit now only needs a 12V power supply (and if chosen) a LAN network cable. No more wiring puzzle in the cockpit, which will be especially helpful in the hardly accessible MIP.
One change was done compared to the Dotsha747 hardware: the encoder to tune the display brightness was connected to the display driver board as follows: Encoder Button is connected directly to display driver button “Menu”. Encoder signals are sent to Rasperry Pi and transformed to Up&Down pulses driving the display driver buttons “Up” and “Down” via the transistors Q2 and Q3 (DSPY and FAIL LED’s which are not supported by ZIBO anyway. Please watch out for R24 and R25 which I had to switch on my PCB Version 3.3.
PLEASE MAKE SURE THAT YOU CONNECT PIN 1 of the FMC PCB to PIN 1 OF THE RASPERRY PI.
This is straight forward with the rasperry pi zero which can be directly plugged into the connector of the FMC PCB without a cable. But you have to turn around the whole pin assignment by use of a female to female 40 pin connector if you mount the rasperry pi 3b over a flat wire cable. (I have burned a rasperry pi by this mistake, please be careful).
Our open source software package xpcockpit was extended by a Rasperry Pi module called xppi (Many thanks Piki for your edits!) and we also have adapted the OpenGC module Boeing737FMC for more performance and with an option to simply display the FMC screen without the keys.