This low cost AVR-based Sous-Vide Cooker is able to auto-calculate the appropriate time for cooking a certain thickness of meat using heat transfer equations. It can maintain a set temperature for extended periods of time. The project implements advanced features such as a water level monitor and automatic timer that can set cooking times depending on the quantity of food cooking.
To monitor the temperature of the water, the immersion cooker project uses solid state temperature sensor with tight degree accuracy. LCD is used to displaying settings information and current temperature and keypad for inputting settings. To control the immersion heater and water pump, we opted for using a junction box with standard wall plugs controlled by a relay module. This would allow us to change what kind of heater and pump we could use, said Harrison Wong and David Diner, the project designer.
In the software part, the project uses the TinyRealTime (TRT) kernel for running code and model the system using a proportional-integral-derivative (PID) controller due to lag between heating the water and when the water is circulated and the temperature sensor registers the change. In addition to the microcontroller code, there is an Android application which can send commands over Bluetooth to the microcontroller. This application scans for available Bluetooth devices, prompts the user to pair with a device, and then allows the user to type in and send messages to the microcontroller.
Project Firmware, Schematic and Documentation