I built a smart Bread Proof Monitor because timers are a pretty terrible way to tell when dough is actually done rising.

This ESP32-based monitor uses a distance sensor to watch the dough rise, tracks temperature and humidity, knows what recipe and proofing stage I’m working on, reminds me about things like stretch-and-folds, and can send a notification to my phone when it’s time to come back and check the dough.

I started with a simple hand-wired version mounted to a Cambro lid, then eventually designed a custom PCB to make the sensors more stable and the whole thing easier to assemble. Both versions run the same software, and all of the code, wiring information, PCB files, and documentation are available below if you want to build your own.

The Proof Monitor is meant to help you know when to check your dough, not replace the recipe or your own judgment. Different flour, yeast, starter, temperature, and hydration can all change what a good proof looks like, so the included targets are starting points. The monitor can also learn from your results and gradually adjust individual recipe targets based on whether you tell it a proof was underproofed, just right, or overproofed.

The Bread Proof Monitor software, wiring information, PCB design files, and documentation are released through the GitHub project. Check the repository for the latest firmware and updates before building or updating your monitor.

NEXTPCB sponsored the PCB portion of this project and manufactured the carrier boards shown in the video. They provided the PCBs and manufacturing services for this project. I paid the applicable import duties myself.

Products Mentioned

ELEGOO ESP32 development boards

View Product

HiLetgo SHT31-D Temperature and Humidity Sensor

View Product

2pcs VL53L0X Time-of-Flight Ranging Sensor Flight Distance Measurement Module

View Product

USB C Cable 3.3ft, Right Angle USB C Cable 60W

View Product

Tools & Equipment Used

FNIRSI HS-03 Cordless Soldering Iron Kit

View Product