{"product_id":"gecko-i-o-expander-i-c-digital-analog-pwm-expander","title":"Gecko I\/O Expander — I²C Digital, Analog \u0026 PWM Expander","description":"\u003cdiv class=\"product-main__prose page-prose\"\u003e\n\u003csection class=\"prose-block prose-block--lead\"\u003e\n\u003cp\u003eThe Gecko I\/O Expander adds programmable mixed-signal I\/O to any microcontroller or single-board computer that speaks I²C. Where a traditional expander handles only digital signals, Gecko combines digital I\/O, 10-bit analog input, 8-bit PWM output, and an integrated high-current amplifier on a single board at one I²C address.\u003c\/p\u003e\n\u003cp\u003eAvailable in 9-channel (GEKO ATtinyx24) and 15-channel (GEKO ATtinyx26) configurations, with configurable addressing so multiple boards chain on the same two-wire bus. Designed and assembled in Pittsboro, North Carolina.\u003c\/p\u003e\n\u003c\/section\u003e\n\u003csection class=\"prose-block\"\u003e\n\u003ch3\u003eOne board replaces four\u003c\/h3\u003e\n\u003cp\u003eEvery 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.\u003c\/p\u003e\n\u003c\/section\u003e\n\u003csection class=\"prose-block\"\u003e\n\u003ch3\u003eWhat each pin can do\u003c\/h3\u003e\n\u003cp\u003eEvery 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:\u003c\/p\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eDigital input\u003c\/strong\u003e — read a switch, button, or logic level\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eInput with pull-up\u003c\/strong\u003e — internal pull-up engaged, fewer external parts\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDigital output\u003c\/strong\u003e — drive a line high or low\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eAnalog input\u003c\/strong\u003e (select pins) — 10-bit, 1024 levels: temperature, pressure, light, moisture, gas, potentiometers, battery\/supply monitoring, current and Hall-effect sensing\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003ePWM output\u003c\/strong\u003e (select pins) — 8-bit, 256 levels: LED dimming, DC motor and fan speed, proportional valves and heaters, servo control\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/section\u003e\n\u003csection class=\"prose-block\"\u003e\n\u003ch3\u003eIntegrated high-current drive\u003c\/h3\u003e\n\u003cp\u003eThis 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 15-channel model) so selected outputs drive real-world loads directly, removing an entire sub-circuit from every project that switches more than an LED.\u003c\/p\u003e\n\u003c\/section\u003e\n\u003csection class=\"prose-block\"\u003e\n\u003ch3\u003eChainable, and wide-voltage\u003c\/h3\u003e\n\u003cp\u003eEach 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 15-channel boards for 30 pins, four for 60, and so on — all on the host's two existing signal wires, with no host redesign as a prototype scales into production.\u003c\/p\u003e\n\u003cp\u003eGecko 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).\u003c\/p\u003e\n\u003c\/section\u003e\n\u003csection class=\"prose-block\"\u003e\n\u003ch3\u003eTechnical specifications\u003c\/h3\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eSpecification\u003c\/th\u003e\n\u003cth\u003e9-channel (ATtinyx24)\u003c\/th\u003e\n\u003cth\u003e15-channel (ATtinyx26)\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eTotal I\/O\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e9 (+ I²C + UPDI)\u003c\/td\u003e\n\u003ctd\u003e15 (+ I²C + UPDI)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eAnalog input\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003e10-bit ADC, 8 single-ended \/ 12 differential, programmable gain\u003c\/td\u003e\n\u003ctd\u003e10-bit ADC, 11 single-ended \/ 8 differential, programmable gain\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003ePWM output\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd colspan=\"2\"\u003e8-bit (256 levels) on select pins\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eTimers\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd colspan=\"2\"\u003e8-bit and 16-bit\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eMemory\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd colspan=\"2\"\u003e2 KB FLASH (4\/8 KB optional) · 128 B EEPROM (256\/512 B optional) · 128 B SRAM\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eHigh-current drive\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd\u003ePre-wired ULN2003 footprint\u003c\/td\u003e\n\u003ctd\u003eULN2003 installed — up to 50 V, 0.5 A (separate +VDD)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eSupply voltage\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd colspan=\"2\"\u003e1.8 V to 5 V (3.3 V compatible)\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eInterface\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd colspan=\"2\"\u003eI²C, configurable address, dual bus connectors for chaining; UPDI programming\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eHost compatibility\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd colspan=\"2\"\u003eAny I²C MCU\/SBC — Arduino, Raspberry Pi, ESP32, Pi Pico, STM32, industrial PLCs\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003e\u003cstrong\u003eAssembly\u003c\/strong\u003e\u003c\/td\u003e\n\u003ctd colspan=\"2\"\u003ePittsboro, North Carolina, USA\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003cp\u003e\u003cem\u003eA 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 datasheet — request the current revision via the \u003ca href=\"\/pages\/contact?flow=support\"\u003esupport page\u003c\/a\u003e.\u003c\/em\u003e\u003c\/p\u003e\n\u003c\/section\u003e\n\u003csection class=\"prose-block\"\u003e\n\u003ch3\u003eWhere Gecko fits\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003e\n\u003cstrong\u003eIndustrial control panels\u003c\/strong\u003e — read a dozen sensors, drive indicators, and switch relays from one board while the host handles logic\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eMachine retrofits\u003c\/strong\u003e — mixed switches, analog sensors, lamps, and solenoid valves where board space is tight\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eDevelopment and prototyping\u003c\/strong\u003e — digital, analog, and PWM on one module instead of three breakouts plus a driver circuit\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eTest fixtures\u003c\/strong\u003e — runtime-configurable pins let one stocked board serve many test roles\u003c\/li\u003e\n\u003cli\u003e\n\u003cstrong\u003eOEM integration\u003c\/strong\u003e — license Gecko as a private-label building block; contact us for OEM and white-label terms\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/section\u003e\n\u003csection class=\"prose-block\"\u003e\n\u003ch3\u003eHow Gecko compares\u003c\/h3\u003e\n\u003ctable\u003e\n\u003cthead\u003e\n\u003ctr\u003e\n\u003cth\u003eCapability\u003c\/th\u003e\n\u003cth\u003eDigital-only expander\u003c\/th\u003e\n\u003cth\u003eStandalone ADC\u003c\/th\u003e\n\u003cth\u003ePWM driver\u003c\/th\u003e\n\u003cth\u003eGecko\u003c\/th\u003e\n\u003c\/tr\u003e\n\u003c\/thead\u003e\n\u003ctbody\u003e\n\u003ctr\u003e\n\u003ctd\u003eDigital I\/O\u003c\/td\u003e\n\u003ctd\u003eYes\u003c\/td\u003e\n\u003ctd\u003eNo\u003c\/td\u003e\n\u003ctd\u003eNo\u003c\/td\u003e\n\u003ctd\u003e\u003cstrong\u003eYes\u003c\/strong\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eAnalog input\u003c\/td\u003e\n\u003ctd\u003eNo\u003c\/td\u003e\n\u003ctd\u003eYes\u003c\/td\u003e\n\u003ctd\u003eNo\u003c\/td\u003e\n\u003ctd\u003e\u003cstrong\u003eYes\u003c\/strong\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003ePWM output\u003c\/td\u003e\n\u003ctd\u003eNo\u003c\/td\u003e\n\u003ctd\u003eNo\u003c\/td\u003e\n\u003ctd\u003eYes\u003c\/td\u003e\n\u003ctd\u003e\u003cstrong\u003eYes\u003c\/strong\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eHigh-current drive\u003c\/td\u003e\n\u003ctd\u003eNo\u003c\/td\u003e\n\u003ctd\u003eNo\u003c\/td\u003e\n\u003ctd\u003eLimited\u003c\/td\u003e\n\u003ctd\u003e\u003cstrong\u003eYes\u003c\/strong\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eChainable\u003c\/td\u003e\n\u003ctd\u003eYes\u003c\/td\u003e\n\u003ctd\u003eLimited\u003c\/td\u003e\n\u003ctd\u003eLimited\u003c\/td\u003e\n\u003ctd\u003e\u003cstrong\u003eYes\u003c\/strong\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003ctr\u003e\n\u003ctd\u003eExternal drivers\u003c\/td\u003e\n\u003ctd\u003eUsually\u003c\/td\u003e\n\u003ctd\u003eN\/A\u003c\/td\u003e\n\u003ctd\u003eSometimes\u003c\/td\u003e\n\u003ctd\u003e\u003cstrong\u003eNot needed\u003c\/strong\u003e\u003c\/td\u003e\n\u003c\/tr\u003e\n\u003c\/tbody\u003e\n\u003c\/table\u003e\n\u003c\/section\u003e\n\u003csection class=\"prose-block\"\u003e\n\u003ch3\u003eIn the box\u003c\/h3\u003e\n\u003cul\u003e\n\u003cli\u003eGecko I\/O Expander module (9-channel or 15-channel)\u003c\/li\u003e\n\u003cli\u003eQuick-start reference card\u003c\/li\u003e\n\u003cli\u003eFirmware, library, and documentation downloads via the SAM Controllers support portal\u003c\/li\u003e\n\u003c\/ul\u003e\n\u003c\/section\u003e\n\u003c\/div\u003e","brand":"SAM Controllers","offers":[{"title":"Default Title","offer_id":46444816466117,"sku":null,"price":0.0,"currency_code":"USD","in_stock":true}],"thumbnail_url":"\/\/cdn.shopify.com\/s\/files\/1\/0661\/4106\/1317\/files\/photo_2026-06-22_13-32-57_4.jpg?v=1782156140","url":"https:\/\/samcontrollers.com\/products\/gecko-i-o-expander-i-c-digital-analog-pwm-expander","provider":"SAM Controllers Store","version":"1.0","type":"link"}