floats-2022

All the code for the 2022 Senior float.

This year's electrical components include the opening and closing hatch, the fog machine, the radio, the monitor, and the LED lights. Mechanically, these systems are connected like so:

graph TD;
    Pi(Raspberry Pi)-->|HDMI|Monitor;
    Pi-->|Bluetooth|Radio;
    Pi-->|GPIO pin 13|TalonSRX;
    TalonSRX-->CIM;
    T{{120V->12V Transformer}}-.->TalonSRX;
    T-.->R1
    T-.->Sign
    Pi-->|GPIO pin 17|L1[Limit Switch 1];
    Pi-->|GPIO pin 27|L2[Limit Switch 2];
    Pi-->|GPIO pin 24|R1[Relay 1];
    R1-->LEDs
    Pi-->|GPIO pin 23|R2[Relay 2];
    R2-->F[Fog Machine];
    E1{{Extension Cord}}-.->T;
    E1-.->F[Fog Machine];
    E1-.->Pi;
    E1-.->Monitor;
    E1-.->Radio;

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Last year's floats code can be found here.

Overall structure

This year's code utilizes multiprocessing to run several submodules in parallel. Individual modules are located in /modules, and (with the exception of schedule.py) are designed to be able to run by themselves. To run a single module, run its corresponding script in /modules. To run all modules simultaneously with multiprocessing, run main.py.

All scripts were designed to run on a Raspberry Pi with the newest OS image and Python 3.9.2.

Schedule

The schedule module parses and updates internal schedule data states, using multiprocessing Events to alert other processes to state changes.

schedule.json is a modified WATT schedule JSON with 0th and 8th periods removed to keep the school start and end times at their expected values; because of WATT's updated array-based syntax, these schedules are easier to parse than those used on the 2021 float. The script no longer checks the MM-DD formatted date, instead using the current weekday to load the schedule.

Radio

python3 ./modules/radio.py

The radio module maintains a similar architecture to last year's radio2.py, reading .wav files from ./music and playing them in a tick-based loop. The script begins playing music 45 minutes before school, sets volume to 10% during class time, and stops playing music 15 minutes after school.

This year's music playlist can be found here: https://www.youtube.com/playlist?list=PL7WwPfnTGk9HsZMm-G_JlF1buJ8Nit32S

Hatch

python3 ./modules/hatch.py

The hatch module runs the hatch mechanism on the float. It turns on the LEDs and fog machine and runs the motor forward, waiting 3 seconds before turning the LEDs and fog machine off and closing the hatch again. The module reads limit switch input to determine the position of the hatch, timing out after 5 seconds in case of limit switch failure. The hatch only runs during passing period, 45 minutes before school, and 15 minutes after school.

hatch.py uses RPi.GPIO software PWM, and as such is inconsistent at controlling the motor (especially when CPU is being taken by other tasks, such as the radio or video). To run the hatch with hardware PWM, see the next section.

Hatch (with hardware PWM)

python3 ./modules/hatch2.py

hatch2.py runs the same logic as hatch.py, but uses pigpio hardware PWM instead of RPi.GPIO. hatch2 requires the pigpio daemon running with

sudo pigpiod

or sudo pigpiod -g in a different terminal window if it needs to be terminated easily. Because pigpio uses the hardware PWM peripheral to generate PWM signal, it cannot be run with radio.py while audio output is set to the AV jack because the Pi uses the PWM peripheral to play audio over aux (see also: similar stackexchange question, pigpio docs). Instead, connect to the speaker over bluetooth; audio will work then.

To run the radio and hardware PWM hatch simultaneously, run

python3 main2.py

instead.

Running on boot

To run the float software on boot, add the following lines to the end of /etc/rc.local:

sudo pigpiod
python3 main2.py &

replacing main2.py with the absolute path to the file.

Tests

/tests contains test scripts to unit-test specific components of the float. The following is a list of tests and what they test for:

Test	Description
relay_test.py	Tests controlling relays with the Raspberry Pi. This test activates both relays for 5 seconds, then turns them off again.
motor_test.py	Tests running a TalonSRX with PWM signal from the Raspberry Pi's GPIO pins. This test sweeps the motor from 0 to full forward power, then to full reverse power, then back to 0.
limit_switch_test.py	Tests reading limit switch input with the Raspberry Pi. This test starts a loop that logs to the console every rising edge it detects over the two configured limit switch pins in constants.py.
limit_switch_motor_test.py	Tests controlling a TalonSRX with limit switch input. This test runs the talon at 0.5 power, toggling it between forward and reverse on limit switch hits.
hardware_relay_test.py	relay_test.py, but using pigpio instead of RPi.GPIO.
hardware_motor_test.py	motor_test.py, but using pigpio instead of RPi.GPIO (hardware instead of software PWM).
hardware_limit_switch_test.py	limit_switch_test.py, but using pigpio instead of RPi.GPIO.
hardware_limit_switch_motor_test.py	limit_switch_motor_test.py, but using pigpio instead of RPi.GPIO.

All hardware tests require running the pigpio daemon.