Custom GPIO Interaction

Note

GPIO_IN and GPIO_OUT (BCM pin numbers, in SETTINGS) must be configured before using GPIO in tasks. See GPIO for what a GPIO pin is, the voltage it works at, and how to wire one.

The system watches an input pin (GPIO_IN) while a task is running. Every time it goes from OFF (low) to ON (high) the trigger_on method of GpioTriggerBase is called; every time it goes from ON back to OFF, trigger_off is called. By default both do nothing. You can override them to react to an external signal (an optogenetics TTL, a lickometer, another box, …).

Note

The output pin (GPIO_OUT) is unrelated to the trigger and available at all times — see Using the output pin.

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Creating a custom GpioTrigger

Create a file named gpio_trigger.py inside your project’s code directory and define a class named GpioTrigger that inherits from GpioTriggerBase. The system will automatically detect it and use it instead of the default base class.

from village.custom_classes.gpio_trigger_base import GpioTriggerBase


class GpioTrigger(GpioTriggerBase):

    def __init__(self) -> None:
        super().__init__()

    def trigger_on(self) -> None:
        """Called when the input pin goes from OFF to ON.

        Available via self.task:
        - self.task.cam_box      — box camera (write_text, areas, position, …)
        - self.task.bpod         — Bpod controller (send_softcode_to_bpod, …)
        - self.task.gpio         — set_on()/set_off() for the output pin
        - any attribute defined in the task class
        """
        self.task.cam_box.write_text("GPIO: ON")
        self.task.bpod.send_softcode_to_bpod(1)

    def trigger_off(self) -> None:
        """Called when the input pin goes from ON to OFF."""
        self.task.cam_box.write_text("GPIO: OFF")

Note

trigger_on/trigger_off run in the GPIO reader thread, not in the task thread. Keep them fast and avoid blocking calls.