Hardware

The hardware part consists these core components

• Shift register-based lamp driver (On SPI bus, SS pin is BTN_CSL)
• Shift register-based button scanner (On SPI bus, SS pin is BTN_CSB, 2 shift register daisy chained)
• HD44780-compatible LCD in 16x2 configuration for status display and system configuration (On LCD_* pin)
• Rotary encoder with push button for service menu navigation and run-time touchpad mode switching (RE on QEI_A and QEI_B pins, push button on QEI_SW pin)
• MAX3421E-based USB host shield for DS4 authentication relay and DS4 passthrough (Controlled by USB_Host_Shield library. USBH_* pin definitions have no real use and are solely for documentation purpose)
• Membrane potentiometer (Left side on SP_L and right side on SP_R)

See src/pin_config.h for symbols.