The SX1509 breakout provides 16-channel GPIO expansion via I2C. With a two-wire interface, your microcontroller can access 16 fully configurable digital input/output pins. Key capabilities - PWM output for LED dimming, with options to flash at different speeds or breathe the pins. - Integrated keyboard engine supporting up to 64 keys in an 8x8 matrix. Compact design - Top and bottom headers serve as the input and control headers for power, SDA, and SCL signals. GPIO and power buses are split in multiple directions, and configurable jumpers cover the remaining wiring. Performance and compatibility - Independent I/O banks can operate from 1.2 V to 3.6 V, with 5.5 V tolerance, enabling use as a level shifter. - Breakout board simplifies prototyping and allows you to add more I/O to Arduino or other controllers with limited I/O. Use scenarios - LED arrays: control brightness with PWM, plus flashing or breathing effects for indicators or ambient lighting. - Keypad input: implement a compact 64-key matrix for custom controllers. - IO expansion: extend an Arduino or similar device’s I/O capacity and handle cross-voltage signaling between components.