Features

• I²C interface
• 8 or 16 controllable GPIO pins
• Pin modes: Input, Input Pullup, Output, Analog Input, PWM Output
• 10-bit analog readings (on select pins)
• 8-bit PWM output (on select pins)
• Chainable end to end
• Power supply from 1.8 V to 5 V

One board replaces four

Every embedded project eventually runs out of pins. The usual answers — a bigger MCU, a stack of single-function chips (digital expander + ADC + PWM driver + external transistors), or cutting features — each add cost, board space, and software overhead. Gecko consolidates all four roles into the footprint previously occupied by a single-function chip, eliminating three to four separate components and the BOM lines, layout, and debugging that come with them.

What each pin can do

Every GPIO is software-configurable at runtime over I²C as one of five modes, so the same board can be reconfigured in the field or reused across product variants without hardware changes:

• Digital input — read a switch, button, or logic level
• Input with pull-up — internal pull-up engaged, fewer external parts
• Digital output — drive a line high or low
• Analog input (select pins) — 10-bit, 1024 levels: temperature, pressure, light, moisture, gas, potentiometers, battery/supply monitoring, current and Hall-effect sensing
• PWM output (select pins) — 8-bit, 256 levels: LED dimming, DC motor and fan speed, proportional valves and heaters, servo control

Integrated high-current drive

This is where Gecko departs most from a standard expander. A typical expander pin sources or sinks only a few milliamps — fine for logic, not enough for a relay, solenoid, or indicator lamp without external transistor circuitry. Gecko includes an on-board amplifier stage (ULN2003-class, up to 50 V / 0.5 A per output on the 16-GPIO model, separate +VDD) so selected outputs drive real-world loads directly, removing an entire sub-circuit from every project that switches more than an LED.

Chainable, and wide-voltage

Each board carries a configurable I²C address; change the address selection and multiple Geckos share one bus, each answering only to its own commands. Chain two 16-GPIO boards for 32 pins, four for 64, and so on — all on the host's two existing signal wires, with no host redesign as a prototype scales into production.

Gecko runs from a 1.8 V to 5 V supply, so a single part number covers low-power 1.8 V designs, 3.3 V systems (Raspberry Pi, ESP32, Pi Pico, STM32, ARM Cortex), and 5 V logic (classic Arduino, industrial PLCs).

Technical specifications

A free I/O library is provided with purchase. Pin-by-pin capability (which pins support analog, PWM, and amplified drive) is detailed in the Gecko Product Guide — see Documentation below.

Where Gecko fits

• Industrial control panels — read a dozen sensors, drive indicators, and switch relays from one board while the host handles logic
• Machine retrofits — mixed switches, analog sensors, lamps, and solenoid valves where board space is tight
• Development and prototyping — digital, analog, and PWM on one module instead of three breakouts plus a driver circuit
• Test fixtures — runtime-configurable pins let one stocked board serve many test roles
• OEM integration — license Gecko as a private-label building block; contact us for OEM and white-label terms

How Gecko compares

In the box

• Gecko I/O Expander module (8-GPIO or 16-GPIO)
• Quick-start reference card
• Firmware, library, and documentation downloads via the SAM Controllers support portal