filter-every-well

Control a Waters Positive Pressure-96 Processor (PP96) using a Raspberry Pi Zero 2W and a 16‑channel motor HAT. This project exposes a small Python API and a simple CLI for driving two servos (press up/down/neutral) and a linear actuator (plate in/out).

Note: When hardware dependencies are not installed, the CLI runs in dry-run mode. Install with pip install .[hardware] on your Raspberry Pi to enable actual control.

Hardware

• Raspberry Pi Zero 2W
• PCA9685 16‑channel PWM/servo HAT at I2C address 0x40
• Two servos on channels 0 & 1 (mirror-mounted, servo_2 = 180° - servo_1)
• Linear actuator on channel 2 (controlled as a servo)

The two servos rotate in opposite directions (mirrored) to press the same position on mirror-image rocker buttons. All servos configured with 500-2500µs pulse width range.

Installation

Python 3.9+ is required.

# From source (editable):
pip install -e .

# Or build a wheel/sdist and install
python -m pip install build
python -m build
pip install dist/*.whl

Optional hardware dependencies

Install with extras to pull in common libraries for the PCA9685 on Raspberry Pi:

pip install .[hardware]

This extra includes:

• adafruit-circuitpython-servokit (which pulls in pca9685 and blinka)

Usage

CLI

# Move press
filter-every-well up
filter-every-well down
filter-every-well neutral

# Move plate
filter-every-well plate in
filter-every-well plate out

Python API

from filter_every_well import PressureProcessor

# Context manager ensures proper cleanup
# On initialization: servos to neutral (90°), actuator to OUT (180° - resting state)
with PressureProcessor() as pp96:
    # Control press (servo 1 / servo 2 mirrored)
    pp96.press_up()        # 30° / 150°
    pp96.press_down()      # 150° / 30°
    pp96.press_neutral()   # 90° / 90°
    
    # Control plate actuator (only IN and OUT, with smooth movement)
    pp96.plate_in()        # Retract to 0° (pull - plate under press)
    pp96.plate_out()       # Extend to 180° (push - plate away, resting state)
    
    # Optional: instant movement without speed control
    pp96.plate_in(smooth=False)
    pp96.plate_out(smooth=False)

# Or manual initialization with custom configuration
pp96 = PressureProcessor(
    channels=16,
    address=0x40,
    servo_1_channel=0,           # Primary servo
    servo_2_channel=1,           # Mirrored servo (180 - servo_1)
    actuator_channel=2,          # Linear actuator
    servo_up_angle=30.0,         # Servo 1 angle for UP
    servo_down_angle=150.0,      # Servo 1 angle for DOWN
    servo_neutral_angle=90.0,    # Neutral position
    actuator_in_angle=0.0,       # Actuator retracted (plate in/pull)
    actuator_out_angle=180.0,    # Actuator extended (plate out/push - resting)
    actuator_speed_percent=60,   # Actuator movement speed 1-100%
    pulse_min=500,               # Pulse width range
    pulse_max=2500,
)
pp96.press_up(hold_time=0.5)
pp96.shutdown()

Development

• Project metadata is defined in pyproject.toml (PEP 621)
• Source lives under src/filter_every_well/
• Entry point script filter-every-well maps to filter_every_well.cli:main

License

MIT. See LICENSE.