⏱ Trigger System for EEG/MEG: Trigger Dictionary + `TriggerSender`¶

Store your event codes in a plain dictionary and let TriggerSender handle the dispatch. This keeps your configuration centralized and your send logic simple.

🧵 Summary of Key Methods¶

`TriggerSender`¶

Purpose	Method
Send a trigger	`.send(code)`
Use mock/debug mode	`TriggerSender(mock=True)`
Add hooks (start/end)	`on_trigger_start/on_end`
Control post-delay	`post_delay=0.001`

🗂 1. Prepare a Trigger Dictionary¶

Store event labels (e.g., “cue_onset”, “response”) as keys in a dictionary with integer codes as values.

A. Define manually¶

triggers = {
    "cue_onset": 32,
    "key_press": 33,
}

B. Load from YAML¶

YAML format:

triggers:
  cue_onset: 32
  key_press: 33

Code:

import yaml
with open("trigger_config.yaml") as f:
    triggers = yaml.safe_load(f)["triggers"]

C. Get a code¶

code = triggers["key_press"]  # returns 33

2. Sending Triggers with `TriggerSender`¶

TriggerSender handles the dispatch logic. It wraps your actual send function (e.g., serial port) and can also run in mock/debug mode.

A. Real device example¶

def send_to_port(code):
    serial_port.write(bytes([code]))

sender = TriggerSender(send_to_port)

B. Mock mode for testing¶

sender = TriggerSender(mock=True)

C. Sending a trigger¶

sender.send(triggers["cue_onset"])

This prints:

[MockTrigger] Sent code: 32
[Trigger] Trigger sent: 32

3. Optional Hooks and Delays¶

You can register actions before/after sending triggers (e.g., opening and closing ports):

sender = TriggerSender(
    trigger_func=send_to_port,
    on_trigger_start=lambda: print("Opening port..."),
    on_trigger_end=lambda: print("Closing port..."),
    post_delay=0.005  # Wait 5ms after sending
)

4. Realistic Example¶

Here we used mock mode for testing and a serial port for real device communication.

trigger_config = {
    **config.get('triggers', {})
}
ser = serial.serial_for_url("loop://", baudrate=115200, timeout=1)
triggersender = TriggerSender(
    trigger_func=lambda code: ser.write([1, 225, 1, 0, (code)]),
    post_delay=0.005,
    on_trigger_start=lambda: ser.open() if not ser.is_open else None,
    on_trigger_end=lambda: ser.close()
)

Using a trigger dictionary with TriggerSender keeps configuration and logic separated, making your experiment easier to debug, replicate, and maintain.

⏱ Trigger System for EEG/MEG: Trigger Dictionary + TriggerSender¶