Sensor Watch Pro turns the Casio F-91W into a modular Arm Cortex M0+-based digital “smartwatch” (Crowdfunding)

Joey Castillo of Oddly Specific Objects has released a follow-up to the Sensor Watch, aptly named Sensor Watch Pro. The Sensor Watch Pro remains a board swap for the classic Casio F-91W or A158W digital watch that replaces the original quartz movement with the low-power ARM Cortex-M0+ microcontroller.

The Sensor Watch Pro retains features from the Sensor Watch Lite and comes with a few upgrades such as a louder piezo buzzer, an RGB LED, an infrared light sensor, and a completely soldering-free experience. The new watch integrates a custom-fabricated metal spring connector that previously had to be manually soldered after purchase. We had also looked at other hackable watches in the past, such as Bangle.js, Bangle.js 2, and Watchy.

Buyers can opt for a custom LCD that extends the number of segments available from 72 segments to 92 segments. It comes with an onboard temperature sensor and can be connected to a MEMS accelerometer sensor board for more points of interaction.

Sensor Watch Pro specifications:

• MCU – Microchip SAM L22 Arm Cortex M0+ microcontroller @ 32 MHz with 32KB RAM, 256 KB of Flash with up to 16 KB EEPROM emulation area
• Display – Low-power 92-segment LCD with improved icons and alphanumeric characters
• USB – 1x USB Micro-B port (for programming)
• Sensors – Ambient light sensor, infrared sensor, temperature sensor, LIS2DW accelerometer with activity and tap recognition
• Expansion
  • Modular 9-pin connector with I2C and five analog inputs or digital IO
  • Edge-plated contacts for three interrupt-capable buttons
• Misc
  • 32.768 kHz crystal for real-time clock functionality with alarm support
  • Red, green & blue PWM’able LED backlight
  • Reset button with double-tap for UF2 bootloader access
• Battery – CR2016 coin cell, 1 to 2 years battery life
• Dimensions – 34.5 x 37.5 x 8.5mm (in enclosure)

While the Sensor Watch Pro is similar to a smartwatch in several ways, it cannot be classified as one due to its simple display and inability to sync with a smartphone. However, it runs a custom, community-developed firmware called Movement that supports dozens of watch faces, including Day/Night Percentage, Interval Timer, Menstrual Cycle, Wordle, Tarot, and Simple Calculator. It is fully open-source, with 3D models, Gerber files, and firmware hosted on GitHub. There is an online firmware builder that allows you to combine the watch faces you want in a UF2 file.

The Sensor Watch Pro crowdfunding campaign is live on Crowd Supply with a funding goal of $35,000. A single board is priced at $75, with a shipping fee of $8 within the US and $18 to the rest of the world. The package includes the custom, 92-segment LCD and LIS2DW accelerometer board.

Tomisin Olujinmi

Tomisin is a writer specializing in hardware product reviews, comparisons, and explainers. He is very passionate about small form factor and single-board computers.

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