#I2C #Lights #Components
The TRRS jack connection between the #Teensy and MCP23018 IO expander was one of the last puzzles I resolved. On breadboard I never got #I2C to work via the jack cable.
Eventually, I noticed that the plug didn't fully reach all four connection points! The extra bit of plastic "collar" on the connectors was preventing the tip from reaching all the way. With the help of a colleague, we figured out that this was the exact problem and cut off the extra plastic.
i²C = -C
ESP32 Bus Pirate Update Adds RF Tools, USB Host Mode, Signal Analysis, and Cellular Plans