This project is a commercial product that we have decided to open source the designs. This project monitors draft beer systems by measuring liquid flow through the beer line, and keeps inventory of how much beer is left in each keg. This inventory data and status are displayed on 7-segment displays using F as Full and E as Empty with 0-9 in between with 0 beeing basically empty and E being displayed after a "kick" is detected by the CO2 spinning the sensor much faster than beer would. In order to quickly signal that a keg has been changed a set of buttons are atached by a parallel bus. When these buttons are held it indicates the keg is changed, if the button is pressed 3 times then held monitoring is suspended. Lastly a 1 wire bus is included to attach multiple thermometers to the device to monitor necesary temperatures such as cooler temp, glycol temp, and ambient temp.
The main breakout board connects any raspberry pi with a 2x20 GPIO header and allows to be connected to several ports for I/O.
RJ45- Sensor Block(2 Sets): These ports send 5V0 and ground across 2 conductors each and recieve inputs on 4 channels. These channels are fed to differential comparators to compare input against a reference voltage which is created by splitting 5V0 across a voltage divider. The output is then sent to GPIO Ports at 3V3.
1-Wire Bus: 1-wire bus intended for DS18B20 temperature sensors, tested up to 8 connected to this bus. Bus consists of a single Gpio port, 3V3 and GND
RJ45-Button Bus: This port sends 5V0 and GND across 1 conductor each and recieves 6 channels of data back which is divided using a voltage splitter down to 3V4. This bus is intended to be used to register button presses. 5-Bits are used as an address, and one bit as an interupt. Each button when pressed will pull Interupt high, along with user selectable bits on each button(Selected by adding a diode to connect button to output)
RJ45- Output Bus: These ports send 5V0, GND and 3 data bits, and recieve 1 data bit. The outputs are a clock, a latch, and a serial out. On the other side of the bus can be any number of SIPO shift registers. Each SIPO's Latch and clock are connected in parallel to the bus, while the serial data is connected to the first register. The next registers serial input is connected to the serial output of the previous register while the last register in the chain connects to the SO pin to send it's output back to the breakout board. This pin is then connected to SI on Output Bus 2 to connect a second chain.