The MVP PFC (Minimal Viable Product) is a minimalist Personal Food Computer developed by OpenAg Community members on the OpenAg Forum, in response to a call placed by MIT Open Agriculture Initiative's Director Caleb Harper to build the “first truly community derived device” for OpenAg.
The OpenAg community's goal is to build something for around $300 (US) that can produce significant research results with minimal investment and skill. The MVP PFC allows for control and research around:
The MVP PFC has the following main parts:
The enclosure is probably the least defined part of the MVP PFC. We have standardized on the size (based on using a bus tub for the reservoir), but are leaving the materials to choice. At this time we have three different prototypes being used: the traditional 'foam farm' made out of insulating foam; one made out of PVC pipe and foil insulation, and one made on a mylar lined cardboard box.
The brain is based around a Raspberry Pi and Python code, with cron used as the scheduler. The latest code is located in Github.
Sensor data is currently logged to a flat file on the Pi's SD card, as well as optionally being stored in CouchDB (on the Raspberry). By using CouchDB, the data is available over the internet. Work is in process to modify the existing PFC (Personal Food Computer) UI to access the MVP data. While both the MVP and PFC use CouchDB, they use different databases with different data structures.
Camera images are stored in a directory as jpg files.
Lighting is standardized on the GE Brit Stik LED (100w equiv, daylight). We are still researching whether two or four are needed. A quick experiment revealed that by removing the end covering and revealing the LED, that the light intensity could be significantly increased.
There are two fans. One is always on for circulation, and the other is thermostat controled for exhaust ventilation.
An Adafruit SI7021 temperature/humidity sensor and USB camera are the only standard sensors; though there are open GPIO pins and two relays available for future or custom expansion.
The current system is hydroponic, the reservoir is a bus tub with an air-pump and stone. Plants are started in rockwool and placed into net pots in the reservior lid. All chemistry (EC and pH) are done manually. There is active research in converting the MVP into an airoponic system. While it will cost a bit more (for the pump) it will eliminate the need for much of the chemistry.