arduino-serial-transmitter/README.md

sleep

cpython's time.sleep calls pysleep: https://github.com/python/cpython/blob/v3.8.5/Modules/timemodule.c#L338

pysleep calls Sleep, probably the one defined in Modules/_tkinter.c, with millisecond precision (rounding up): https://github.com/python/cpython/blob/v3.8.5/Modules/timemodule.c#L1873

Modules/_tkinter.c:Sleep (https://github.com/python/cpython/blob/v3.8.5/Modules/_tkinter.c#L361):

static void
Sleep(int milli)
{
    /* XXX Too bad if you don't have select(). */
    struct timeval t;
    t.tv_sec = milli/1000;
    t.tv_usec = (milli%1000) * 1000;
    select(0, (fd_set *)0, (fd_set *)0, (fd_set *)0, &t);
}