The option
-TR_times xx
will set the TR for the -iresp (and -sresp) outputs from -stim_times options to 'xx' seconds. Since the -stim_times option computes the impulse response function as a series expansion, it is easy for this expansion to be evaluated at an arbitrarily fine temporal grid.
You should read
[
afni.nimh.nih.gov]
[
afni.nimh.nih.gov]
for the details about the -stim_times method of specifying the stimulus timing and model all at once.