Data Sheet

to delay I²C communication while it is busy with other tasks and has not gotten around to processing
data from the master. This means that the Tic is only compatible with I²C masters that also support
clock stretching. It also means that the time to send an I²C command to the Tic is variable, even if you
are only writing data and not reading anything.
The Tic only uses clock stretching at most once per byte. It stretches its clock after it receives a
matching address byte, after it receives a command/data byte, and after it sends a byte that is not the
last byte in a read transfer.
Each time the Tic stretches the clock, it could stretch the clock for as long as 1.5 ms if it is busy running
its step planning algorithm, which it does approximately (but never more frequently than) every 5 ms.
At other times, the Tic will usually stretch the clock for 150 μs or less, depending on the timing of the
I²C bytes and how busy the Tic is performing other tasks.
The “serial response delay” setting can be used to guarantee a minimum amount of clock stretching
each time the Tic stretches the clock.
Tic Stepper Motor Controller User’s Guide © 2001–2018 Pololu Corporation
10. I²C command encoding Page 145 of 150