Front Panel for 8 Bit Computers V2

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SMT version: Tindie-mediums.png

Front Panel for 8-Bit Microprocessors v2


Top row controls

Board has typical control silkscreen markings.



This is a through-hole version of Front Panel for 8_Bit Computers.

It has these features. They may not fit your generic design. Especially since this card has to have an I2C interface.

  • 32 Pushbutton Switches
  • 32 LEDs
  • I2C interface (Two Wire interface - plus power and ground)
    • Jumper selectable base address
    • Occupies I2C addresses either 0x20-0x23 or 0x24-0x27
    • Jumper Selectable I2C terminators
  • I2C daisy-chain connector
    • Interrupt line
      • Can be configured to interrupt on button presses
      • MCP23017 need to be set to Open-Drain output - card has pull-up to Vcc
  • 4 of MCP23017 16-bit I2C Port Expanders
    • These are fine pitch surface mount parts
  • 3.3V or 5V operation
  • Compatible form factor with RETRO-EP4CE15 and other cards
    • 95x95mm
    • 6-32 mounting holes


J2 - I2C Connector

  • Two row header on bottom of card
  • 5 pin in
  • 4 pin out (daisy-chain)
  1. GND
  2. VCC
  3. SDA
  4. SCL
  5. INT*


  1. GND
  2. VCC
  3. SDA
  4. SCL



VHDL Driver

Arduino Driver

  • I2C parts are standard MCP23017 drivers which are supported in Arduino and most microprocessors


C Code

Assembly Sheet

Front Panel V2 Assembly Sheet Rev 1