# Sensor Watch Lite (Oddly Specific Objects) > A replacement circuit board that turns a Casio F-91W into a programmable ARM Cortex-M0+ watch. - **Category:** Wearables - **Availability:** Listed by maker - **Price:** US$39, checked 2026-09-18 - **Good for:** Rewriting the firmware of a watch you already own. - **You'll need:** A Casio F-91W to transplant it into, and some soldering for the buzzer. - **Trade-off:** No radio; the segment LCD limits what you can show. - **Page:** https://gadgets.sh/devices/sensor-watch-lite/ ## Where to buy | Shop | Status | Link | |---|---|---| | Oddly Specific Objects | Orderable | https://www.crowdsupply.com/oddly-specific-objects/sensor-watch?utm_source=gadgets.sh&utm_medium=referral&utm_campaign=sensor-watch-lite&utm_content=api | ## Blueprint **Open hardware.** Full KiCad schematic, PCB layout and gerbers for the Sensor Watch Lite mainboard (rev OSO-SWAT-B1) are public in the shared Sensor-Watch repo, per the repo's own hardware table. ### Design files - schematic: [Sensorwatch Lite mainboard (OSO-SWAT-B1) KiCad schematic](https://github.com/joeycastillo/Sensor-Watch/blob/main/PCB/Main%20Boards/OSO-SWAT-B1/OSO-SWAT-B1.kicad_sch) (KiCad) - pcb: [Sensorwatch Lite mainboard (OSO-SWAT-B1) KiCad PCB layout](https://github.com/joeycastillo/Sensor-Watch/blob/main/PCB/Main%20Boards/OSO-SWAT-B1/OSO-SWAT-B1.kicad_pcb) (KiCad) - gerbers: [Sensorwatch Lite fab package (rev -03)](https://github.com/joeycastillo/Sensor-Watch/blob/main/PCB/Main%20Boards/OSO-SWAT-B1/OSO-SWAT-B1-03.zip) (ZIP) ### Source repositories - [joeycastillo/Sensor-Watch](https://github.com/joeycastillo/Sensor-Watch) — hardware, ★2078 ### Key parts | Part | Role | Datasheet | |---|---|---| | Microchip SAM L22 (ATSAML22) | MCU + segment-LCD controller | https://ww1.microchip.com/downloads/en/DeviceDoc/SAM-L22-Family-Data-Sheet-DS60001465B.pdf | _Notes:_ Crowd Supply's Sensor Watch Lite page links github.com/joeycastillo/Sensor-Watch. The repo README's own 'Hardware Schematics and PCBs' table explicitly maps 'Sensorwatch Lite' (RED) to board OSO-SWAT-B1 -- distinct from plain 'Sensorwatch' (GREEN, OSO-SWAT-A1) and 'Sensorwatch Pro' (OSO-SWAT-C1, added later -- see that entry). Confirmed by reading the README table directly rather than assuming a folder name. Repo license: GitHub reports NOASSERTION (LICENSE.md has custom, non-standard text). ### Raw source files Direct links an agent or KiCad can open (the viewer on the page reads the same files). - KiCad project **Sensorwatch Lite mainboard (OSO-SWAT-B1) KiCad schematic** (joeycastillo/Sensor-Watch): [OSO-SWAT-B1.kicad_pro](https://raw.githubusercontent.com/joeycastillo/Sensor-Watch/main/PCB/Main%20Boards/OSO-SWAT-B1/OSO-SWAT-B1.kicad_pro), [OSO-SWAT-B1.kicad_sch](https://raw.githubusercontent.com/joeycastillo/Sensor-Watch/main/PCB/Main%20Boards/OSO-SWAT-B1/OSO-SWAT-B1.kicad_sch), [OSO-SWAT-B1.kicad_pcb](https://raw.githubusercontent.com/joeycastillo/Sensor-Watch/main/PCB/Main%20Boards/OSO-SWAT-B1/OSO-SWAT-B1.kicad_pcb) - KiCad project **OSO SWAT C1** (joeycastillo/Sensor-Watch): [OSO-SWAT-C1-rounded.kicad_pro](https://raw.githubusercontent.com/joeycastillo/Sensor-Watch/main/PCB/Main%20Boards/OSO-SWAT-C1/OSO-SWAT-C1-rounded.kicad_pro), [OSO-SWAT-C1.kicad_sch](https://raw.githubusercontent.com/joeycastillo/Sensor-Watch/main/PCB/Main%20Boards/OSO-SWAT-C1/OSO-SWAT-C1.kicad_sch), [OSO-SWAT-C1-rounded.kicad_pcb](https://raw.githubusercontent.com/joeycastillo/Sensor-Watch/main/PCB/Main%20Boards/OSO-SWAT-C1/OSO-SWAT-C1-rounded.kicad_pcb), [OSO-SWAT-C1.kicad_pcb](https://raw.githubusercontent.com/joeycastillo/Sensor-Watch/main/PCB/Main%20Boards/OSO-SWAT-C1/OSO-SWAT-C1.kicad_pcb) - KiCad project **OSO SWAB B1 00 Sensor Watch Accelerometer** (joeycastillo/Sensor-Watch): [OSO-SWAB-B1-00 Sensor Watch Accelerometer.kicad_pro](https://raw.githubusercontent.com/joeycastillo/Sensor-Watch/main/PCB/Sensor%20Boards/Kicad/OSO-SWAB-B1-00%20Sensor%20Watch%20Accelerometer/OSO-SWAB-B1-00%20Sensor%20Watch%20Accelerometer.kicad_pro), [OSO-SWAB-B1-00 Sensor Watch Accelerometer.kicad_sch](https://raw.githubusercontent.com/joeycastillo/Sensor-Watch/main/PCB/Sensor%20Boards/Kicad/OSO-SWAB-B1-00%20Sensor%20Watch%20Accelerometer/OSO-SWAB-B1-00%20Sensor%20Watch%20Accelerometer.kicad_sch), [OSO-SWAB-B1-00 Sensor Watch Accelerometer.kicad_pcb](https://raw.githubusercontent.com/joeycastillo/Sensor-Watch/main/PCB/Sensor%20Boards/Kicad/OSO-SWAB-B1-00%20Sensor%20Watch%20Accelerometer/OSO-SWAB-B1-00%20Sensor%20Watch%20Accelerometer.kicad_pcb) ## Specifications ### Core hardware | | | |---|---| | Processor | ARM Cortex-M0+ up to 32 MHz · 256 KB flash with up to 8 KB EEPROM emulation · 32 KB RAM with full retention in standby | | Display | Drives the original ten-digit segment LCD plus five indicator segments | | Radio | None | | Power | The watch battery; a 32.768 kHz crystal drives the real-time clock | ### Details from the project page | | | |---|---| | Timekeeping | 32.768 kHz crystal for real-time clock with alarm support | | Backlight | Red and green PWM-able LED backlight | | Sensors | On-board temperature sensor | | Programming | USB Micro-B connector and a reset button with a double-tap UF2 bootloader | | Buttons | Edge-plated contacts for three interrupt-capable buttons | | Expansion | A pad for a piezo buzzer (needs light soldering) and two interrupt-capable digital inputs on test points | | Relation to the Pro | The Lite is the current board; the original Sensor Watch is marked no longer available | ### Buying | | | |---|---| | Price | US$39 on Crowd Supply | | Availability | In stock on the day of review | ## Firmware & community - [Movement](https://github.com/joeycastillo/Sensor-Watch) — Community watch faces, accelerometer monitors, and sensor logger complications for the classic Casio F-91W. ## Documentation - [Crowd Supply project page](https://www.crowdsupply.com/oddly-specific-objects/sensor-watch) - [Crowd Supply](https://www.crowdsupply.com) --- Source: gadgets.sh · https://gadgets.sh/devices/sensor-watch-lite/ · JSON: https://gadgets.sh/api/v1/devices/sensor-watch-lite.json