HopperHawk Monitors Pellet Smoker Hopper Levels

Pellet smokers are designed to incrementally feed pellets from an upright hopper into a combustion chamber, maintaining optimum cooking conditions. While this is largely an automatic operation, the hopper eventually needs to be refilled with wood pellet fuel. To monitor pellet levels, Redditor SneakyPackets created the HopperHawk sensor package using a Raspberry Pi Pico W and an HC-SR04 ultrasonic sensor.

While SneakyPackets would have accomplished this with a perfboard/wiring/solder setup, as seen here this hacker instead created a custom printed circuit board to connect hardware and hold it in place. The eventual idea is to have it work on battery power. There is a voltage divider circuit on the PCB so that the battery level can be read via the Pico W’s ADC. There’s also a 3D-printed enclosure being printed to finish off the design.

Software-wise, the measurement operation is fairly straightforward, but SneakyPackets also created a companion app for remote monitoring using Flutter. The app shows the current hopper level, and has a calibration mode that allows one to set up empty and full levels. It even integrates with Home Assistant via MQTT, which currently handles push notifications.

Besides helping to keep pellets at the proper level, creating a PCB for this device also served as good practice for another project that SneakyPackets is cooking up. More project specifics are found at the HopperHawk GitHub repository.