% Free induction decay (FID) — the simplest pulseq sequence.
% A non-selective excitation pulse followed by a long readout,
% repeated 16 times. Adapted from pulseq's demoSeq/writeFid.m.

system = mr.opts('rfRingdownTime', 20e-6, 'rfDeadTime', 100e-6, ...
                 'adcDeadTime', 20e-6);

seq = mr.Sequence(system);
Nx = 4096;      % samples per readout
Nrep = 16;      % repetitions

% 90-degree block (hard) excitation pulse
rf = mr.makeBlockPulse(pi/2, 'Duration', 0.3e-3, 'system', system, ...
                       'use', 'excitation');

% ADC: long readout to capture the full decay
adc = mr.makeAdc(Nx, 'Duration', 512e-3, 'system', system, ...
                 'delay', system.adcDeadTime);
delayTE = 20e-3;
delayTR = 5000e-3;

assert(delayTE >= mr.calcDuration(rf));
assert(delayTR >= mr.calcDuration(adc));

for i = 1:Nrep
    seq.addBlock(rf, mr.makeDelay(delayTE));
    seq.addBlock(adc, mr.makeDelay(delayTR));
end

[ok, error_report] = seq.checkTiming();
if ok
    fprintf('Timing check passed successfully\n');
else
    fprintf('Timing check failed! Error listing follows:\n');
    for k = 1:numel(error_report)
        fprintf('%s\n', error_report{k});
    end
end

seq.setDefinition('Name', 'fid');
seq.write('fid.seq');