Hello,
Some addition to the topic. As far as I know the parameter t in code block is the simulation time, so not necessary to add it from outside.
There is need for fixed time step from some users to simulate discrete control loops or MCU based PWM etc. in code blocks but it is not easy to achieve because the variable time step is (if I understand is correctly) fundamental is spice’s numerical algorithms.
See this topic above, my and ImNotCreative’s comments. I tried to show the time difference between function block callings (I assume this is the jitter what you mentioned), maybe you can use it some way. If you search the forum for code block and fixed time step (if you need that) you can find other and better solutions.