MCP23x08/mcp23x17 References AN1081 Title: Interfacing a 4×4 Matrix Keypad with an 8-Bit GPIO Expander -04/12/2007 Mike Curran https://www.microchip.com/wwwAppNotes/AppNotes.aspx?appnote=en529784 Description: This application note discusses interfacing a 4×4 matrix keypad with MCP23X08 8-Bit GPIO […]

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