specific timing

Hi,
is it a good solution to start a timer in the OnTimer method? This
timer Timer2 should be called only once -> after that the Timer2 will
be killed and restarted after the next Timer1 event.

Some words to the specific timing: every 25ms a new frame will be sent
by the serial interface. Each frame starts with a start condition
(100=B5s low impulse without the stoppbits etc.) after that some
"normal" data will be tx by the serial interface (e.g. with two
stoppbits and so on).

Therefore I have to set/clear some GPIO pins to get this required
timing. Unfortunately Sleep() only works for ms delays; How is it
possible to maintain the timings - only with additional timers?

void OnTimer( UINT_PTR nIDEvent )
{
   if(nIDEvent == Timer1)
  { //will be called every 25ms

   //do some stuff

  ClearGPIO(Pin5);

  //wait 100=B5s - how is that possible - only with an additional
timer???

  SetGPIO(Pin5);

  ClearGPIO(Pin7)
   SetTimer(Timer2, interval2, NULL);

   //WM_FILL_TX_BUFFER will be txd

  } else if(nIDEvent == Timer2)
  { //will be called if fired every 22ms

    SetGPIO(Pin7)

    KillTimer(Timer2);

    //send message to another thread
    PostThreadMessage(WM_FILL_TX_BUFFER, 0); //do some stuff until
Timer1 will be called again
 }
}

The PostThreadMessage() will send a message to another thread, which
has to fill all tx buffers. These buffers will be send during the
OnTimer. How could I satisfy that all buffers will be filled with new
datas, when the next timer interrupt occured?

best regards
Hans