Hangman is a Bluetooth-enabled crane scale. It's intended use is as a climbing training and rehab tool, but it can be used anywhere that requires measuring force or weight.

The hardware retrofits a cheap (~$23) 150kg crane scale from Amazon with a custom PCB based around a Nordic nRF52 microcontroller and a differential ADC. The firmware uses Embassy, an embedded async framework written in Rust, as well as Nordic's SoftDevice Bluetooth stack.

Crane scales have become popular in the climbing community as a means to train and rehab fingers. This is a fun project to learn and practice various concepts I was unfamiliar or rusty with: BLE 101, async Rust on embedded, nRF52 development, SMT soldering and PCB design, etc. Maybe it'll even help my fingers get stronger.

The scale is feature-complete. Weight measurement works great with the Progressor API and compatible tools. Battery life is guesstimated to be in the range of several months to a couple of years depending on usage.

There are still a few more software updates planned. See the Issues section for the major ones.

See title picture. A custom PCB based on a Fanstel BT832 nRF52832-based module and a Texas Instruments ADS1230 ADC. Thanks to a better ADC and PCB layout, noise performance should be improved over previous revisions and most importantly, it's much prettier.

A custom PCB based on a nRF52840 USB dongle and an HX711 ADC, the same differential ADC used on the Tindeq.

• The Embassy project for bringing asynchronous Rust to the embedded world. and creating an easy to use wrapper around the Nordic SoftDevice Bluetooth stack.
• Bumble for BLE testing and prototyping.
• Texas Instruments for their excellent reference materials on load cell circuit design and PCB layout.
• Tindeq for making an amazing product and app and opening their BLE API to third-party developers. Go buy one!

This is not an officially supported Google product. Wouldn't that be funny though?

This has no affiliation with Tindeq.