This DIY Pi-tmaster Wireless Thermometer Can Help You Achieve BBQ Perfection

Ask any man over the age of 40 and he’ll insist that he can tell you when a pork shoulder is done just by looking at it and giving it a good poke. He’s lying and you shouldn’t trust him — you certainly shouldn’t try to emulate his claimed abilities. We’re living in a technological utopia and there is absolutely no reason to rely on intuition when you can collect objective data. A good thermometer can tell you if your smoker is at the right temperature and exactly when to pull off the meat, and JayTongue’s Pi-tmaster is a neat DIY option.

Pi-tmaster is an open source wireless thermometer that can read two sensors and that you can build yourself. There are many, many products on the market with similar functionality, but this is a cool and affordable option for people who like tinkering. It has connections for two K-type sensors, which is perfect for monitoring the grill/smoker temperature and the meat temperature at the same time. It connects to the user’s local WiFi network and makes the temperature readings available on a self-hosted website as JSON data. It also displays the temperatures on a small OLED screen on the device itself.

As you may have already guessed based on the hyphen in the name, the JayTongue designed Pi-tmaster around a Raspberry Pi Pico W development board. It reads the K-type probes using MAX6678 boards, which helpfully make temperature data available via an easy-to-use SPI interface. Power comes from lithium batteries via LX-LCBST charging modules.

That hardware all fits inside a transparent, waterproof hard case. It has holes drilled for the probe connections and that will affect its ability to keep water out, but it should still be more than good enough to deal with any light rain that may blown in during an overnight smoke.

To view the temperatures, users can visit the self-hosted website and look at the JSON data. But that isn’t very pretty, so JayTongue also wrote a couple of Python scripts. One collects that JSON data and the other puts it on a nice graph.

If you want to build your own Pi-tmaster, JayTongue was kind enough to publish all of the files details on GitHub.