16 channel arcade button driver

(Legacy project, no longer in development)

• 16 channels
  • 8 channels for regular (NC and/or NO, depends on the software) buttons
  • 8 channels for illuminated (lamp equipped) buttons
• Programmable lamps
• Button interface are somewhat compatible with CY-822B encoder (shares the same electrical interface) with a better (not hard-wired to VBUS) lamp support.
• Separated lamp power rail (Supports 0-12V PSU, 500mA max for each channel)
• Supports 3.3V (at low speed like 1-2MHz) and 5V logic
• Supports controlling via SPI bus and bitbang with Arduino ShiftIn/ShiftOut code

• Install KiCad
• Plot the board
• Zip the Gerber files and send them to whatever PCB house you like
• TODO components, BOM, etc.
• ???
• PROFIT!

PS: There's no plan for selling the assembled boards or kits at the moment, so too bad for those who just want a working board :<

• First and foremost, I am still very new to PCB layout and routing, so feel free to open an issue to give suggestions on my design and/or point out any mistakes I made.
• The JST connectors are rotated 180 degrees (so pin 1 is on the right side) due to a mistake I made at the very early stage of designing and the quickest way of fixing it is to rotate the connector.
• Make sure you are using the "always on" wiring suggested here (i.e. pin 1 is common ground, pin 2 is button and pin 3 is lamp) for illuminated buttons. Behavior on "illuminate on press" wiring (i.e. reversing pin 1 and pin 2) is undefined (and potentially dangerous if the lamps are powered with voltage higher or lower than VCC since this wiring basically shorts the lamp power to the button pin when the switch on the button is closed)
• The P-channel MOSFET can be swapped for cheaper alternative (e.g. CJL3415) as long as they have the same electrical interface, the parameters (Vds, Vgs, Ids, Rds) are reasonable and proper zener diodes (D1-D8) and voltage divider (R1-R8, R9-R16) are chosen so that the gate of the MOSFET are not overdriven. (In case of CJL3415, a good choice would be 10k for R9-R16, 20k for R1-R8, and zeners with zener voltage of 7.5V) Also, TPIC6C596 can be used in place of TPIC6C595. (Tested)