JohSchneidera quick overview of the modules used (so far), which contribute to the 'M' in the projects name and are designed to support/simplify the (hand) wiring of the keyboard matrix
| the I2C_bridge_primary sits on the microcontroller side (which runs the firmware and does the USB stuff) it's main features are - I2C buffering (for long/unshielded wires) - ESD protection - current limiting 
Parts: - TRRS phone-socket SJ-43514-SMT - current-lim. IC: AP2553W6 - I2C Buffer P82B715 - ESD diodes VESD05a1 - 0805 resistors and capacitors |
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| the I2C_bridge_secondary sits on any of the slave devices (usually one/another keyboard half, but could be multiple other devices) it's main duties are: - I2C buffering - ESD protection
Parts: - TRRS phone-socket SJ-43514-SMT - I2C Buffer P82B715 - ESD diodes VESD05a1 - schottky diode SS14 - 0805 resistors and capacitors |
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| the matrix_Attiny861a mostly an breakout board for an attiny, with pads on the front to directly solder a ribbon-cable which spreads out to the handwired keyboard matrix - ICSP contacts for reprogramming - pads to solder a 4-wire ribbon cable to the device-internal i2c-bus (with the attiny running an i2c-slave firmware) - an expansion header which can be fitted with an 2x6 micro-match connector to add more keys or use the ADC for an analog joystick
Parts: - micro-match socket 1-215460-2 - attiny 861a - 0805 resistors and capacitors |
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| the matrix_MCP23017 - a breakout board for the I2C port-expander - with pads to directly solder a ribbon cable which spreads out to the keyboard matrix - as well as a ribbon cable to the internal i2c bus - 2x6 micro-match expansion header for additions to the keyboard-matrix
Parts: - micro-match socket 1-215460-2 - MCP23017 - 0805 resistors and capacitors |
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