# WORK IN PROGRESS - DO NOT USE FOR PRODUCTION # I'm waiting for a new HDMI LCD to arrive before I finalize this design. *** To Do *** - R30 relocated closer to Q6. *DONE* - Finally fixed bug with GPIO25 and GPIO24. 8-( *DONE* - Fixed Rotary Encoder not connected due to not being aligned to grid. 8-( *DONE* - Changed package for Q1-to-Q6 transistors to ones where the pads are further apart. Matches part from LCSC. - Added mounting holes for KYV-N5-V1 HDMI LCD Driver board. - Added mounting holes for 66.5 x 46.5 LVDS Driver Board (guestimated the position). - Added mounting holes for 65mm switch board. *** Changes in V3.1 *** - Pi is a bit too close to the power supply, hard to remove microSD. Fixed in V3.1. - Changed the package for the BC547 to that of the BC335. Just very slightly easier to solder. Fixed in V3.1. - R2 is on the wrong side of the board. Fixed in V3.1. - exec light should be below the exec button. Fixed in V3.1. Note: Button is moved slight higher, but should still work with the FMC 3D model. - DEALBREAKER: GPIO25 wrongly labelled as GPIO24 in V3.0, resulting in 16 dead keys. Fixed in V3.1. - Relocated all the backlight resistors and all the diodes to the area just below the screen. Easier to find, although the autorouter has a tougher time. - Shifted the mounting holes for the LCD driver to align it with the LCD ribbon cable position. - added two holes to zip-tie the VGA-HDMI adapter down. *** Changes in V3.0 *** - Added socket for Raspberry Pi Zero WH. You can either plug a Raspberry Pi Zero WH directly into this socket, or use a 40-pin IDC ribbon cable (if yo solder male pins) and extend it to any 40-pin GPIO Raspberry Pi model of your choice. - Added socket for MP1484 switching power supply module (https://goo.gl/Xku2Xa). This can be set to step-down 12VDC to 5VDC, suitable for powering the Pi. With this you only need a single 12VDC power supply to power both the Pi and the Display. - Added output 12VDC power connector for the LCD Display. - Added pull-down resistors for the LED indicators, so are off on power up, until driven by the software. - Replaced the switches with LED Push buttons (https://goo.gl/gbQCQg), so we can backlight the keys. LEDs are driven by 12V with a resistor for every 3 LEDs. I've used the yellow version of the switches LEDs with Vf of 2.0V and 330R resistors. If you are using the white LEDs, replace them with 120R resistors. - Added software-controllable dimming control of button backlight, using the Pi's built-in PWM output. - Added Rotary-Encoder input to Pi, to control dimming. - Removed hole for LCD, it's easier to mount it with double sided tape. - Added mounting holes for LCD Driver under the PCB.