Skip to content

ElectronInjection

MCP23017

Multiple MCP23017 Expanders With Interrupts Not Playing Nice

August 14, 2020 by ElectroBrandon

was manually polling my 3 MCP23017 expanders I need for all the buttons for my synth just to get the ball rolling. The serial monitor tells me it was taking almost 5ms….which is similar to the amount of time it’ll take for the dinosaurs to come back. (It’s a billion years in microcontroller land.) I … Read more

Categories Programming Tags Arduino, MCP23017 Leave a comment

Add 32 Buttons With Just 2 Pins With MCP23017 Expander

March 19, 2026June 1, 2020 by ElectroBrandon

I need about 40 buttons for my synth project.  I’m trying to run the entire synth with a single STM32 Blue Pill.  I’ve already shown how I can run 256 LEDs with 3 pins LINK IT HERE.  Since the MCP23017 is I2C, I could possibly run 128 buttons on 2 pins.  For now, I’m just … Read more

Categories Electronics, Programming Tags button, expander, MCP23017

Find Me

  • Github
  • Youtube

Recent Posts

  • Dungeon Controller – STM32 HAL FreeRTOS
  • Idiot Christmas Light Controller
  • YM3812 Synthesizer
  • Big Girl Audio – Audio Power Amplifier
  • POWER INVERTER IN DQ REFERENCE FRAME

Categories

  • 3D Printing
  • Altium
  • C_Code
  • CNC
  • Electronics
  • Guitar_Building
  • Kicad
  • PCB_Design
  • PLCs
  • Portfolio
  • Programming
  • Projects
  • Python
  • Rants
  • Videos

Meta

  • Log in
  • Entries feed
  • Comments feed
  • WordPress.org

Highlights

  • About
  • Blog
    • Engineering Design Principles
    • PCB Checklist
  • Contact
© 2026 ElectronInjection • Built with GeneratePress