AutoBarRpi

An automated cocktail-making machine controlled through the web.

Summary

There are only 3 files that you need to know about in this repository: Controllers.py, main.py, and off.py. off.py is run at system startup, but main.py must be started by hand once the Raspberry Pi system has successfully booted up. To run a script at system startup, put the script in the /etc/rc.local file on the Raspberry Pi.

Controllers

The file Controllers.py contains the code that abstracts away the inner mechanism of the system. The goal of this is to make it so that the main logic programmer does not need to deal with setting pins high and low and handling timing and signal debouncing. Here is how:

PumpController

The PumpController has only 1 static data member and 2 real functions: the constructor and the pump_oz method.

• The static data member SECS_PER_OZ is a constant that is determined experimentally. It represents the number of seconds that it takes for the pump to pump 1 ounce of water. We calculated this value to be around 3 and a half seconds, but you might need something different. This value is hard-coded and cannot be changed through the interface.
• The constructor takes in a dictionary of the pump numbers as strings and the pins to that correspond to the pump as integers. The constructor may through exceptions if the provided dictionary is empty or there was no constructor parameter specified.
• The pump_oz function takes 2 parameters: pump_name and amount_of_liquid. The first parameter is expected to be a string such as '3' and the second is a float representing the number of ounces to be pumped.

MotorController

The MotorController has only 3 functions: the constructor, the turn method, and the stop method.

• The constructor takes in the two pins that are used for communication with the PiC32 board. These two pins are the transmitter pin (tx_pin) and the receiver pin (rx_pin). As expected, the transmitter pin sends data to the PiC32 and the receiver pin receives data from the PiC32.
• The turn method sends a signal to the PiC32 to turn the motor one space, in the direction determined by the PiC32 and not the Raspberry Pi. To do this, it sets the transmitter pin to HIGH for half a second and then sets the pin back to low. The Raspberry Pi will not return from this method until the PiC32 indicates that it has completed the action, indicated by the receiver pin going HIGH for half a second. This is to prevent the main Raspberry Pi logic from pumping liquid while the platter is spinning, which would result in liquid being spilled everywhere. This method takes no parameters.
• The stop method is mainly for debugging and will likely not be used in an actual system. This method simply sets the transmitter pin to LOW in order to stop sending the turn signal to the PiC32. This should not be necessary unless the Raspberry Pi somehow is interrupted before it is able to complete a call to the turn method.

Main

The main function can be broken down into 2 sections: the initialization section and the main loop section.

Summary

The main controller logic works by polling on the /orders.json URL of the Ruby on Rails application looking for a JSON object of the data that needs to be processed for an Order. This data includes the user who placed the Order, along with their drivers license number, and the list of up to 5 drinks that the user ordered.

Once this data is acquired from the web application, it will ask the user to swipe their ID card on the actual Autobar device. This data from the drivers license is used to 1) verify that the user at the Autobar is the same user that submitted the drink Order and 2) that the user that submitted the Order is over the legal drinking age.

Initialization

This is the section where the pin mapping is set up, the PumpController and MotorController are instantiated, the polling URL is specified, and the debug Boolean is set. This is only run one time during the main program's execution.

Main Loop

This main loop is broken into two parts: one where only a simplified test version of the code is run and one where the web application is actually polled for live Order data. The test version is very simple and just makes the same drink 3 times on loop. The non-test version of the code performs all of the actions outlined above.

Off

This short script simply signals for all of the devices to be turned off. No pumps or motors should be running after this script is finished. Note, however, that this pins values are hard-coded in, so it is not the best system. This script is run at system startup to initialize the pins before all hell breaks loose.