makeTrigger

Creates a trigger event for synchronization with an external signal. This function generates a structure defining a trigger event for use within a Pulseq sequence. It specifies the trigger channel, delay before the trigger, and duration after the trigger. The duration is constrained to be at least as long as the system's gradient raster time.

Syntax

function trig = makeTrigger(channel, varargin)

Calling Pattern

mr.makeTrigger(...)
mr.makeTrigger('ParameterName', value, ...)

Parameters

This function accepts both positional parameters and name-value pairs.

Required Parameters

Parameter Name	Value Type	Description	Example	Units
channel	char	The channel to use for the trigger. Valid values are 'physio1' and 'physio2' (Siemens-specific).	'physio1'

Name-Value Pair Arguments

Parameter Name (string)	Value Type	Default	Description	Example
delay	double	0	The delay (in seconds) before the trigger event starts. (Units: seconds)	0.001
duration	double	0	The duration (in seconds) of the trigger event. If shorter than the system's gradient raster time, it is automatically adjusted to match the raster time. (Units: seconds)	0.005
system	struct	[]	A structure containing system parameters (e.g., from mr.opts()). If not provided, mr.opts() is used.	mr.opts()

Returns

Output	Value Type	Description
trig	struct	A structure defining the trigger event. Contains fields: type ('trigger'), channel (the selected channel), delay (delay before trigger), and duration (duration of trigger).

Examples

% Physiological trigger for cardiac gating with extended duration
trig = mr.makeTrigger('physio1','duration', 2000e-6);

% Simple physiological trigger on channel 1
trig = mr.makeTrigger('physio1');

% Trigger with custom system parameters
sys = mr.opts('gradRasterTime', 10e-6);
trig = mr.makeTrigger('physio2','system', sys);

See Also

Sequence.addBlock, mr.opts