MC9S0AC16 I/O direction lost at wake up from Stop3 until registers are re-initialised.

[Remiforcet22]

  Hi,

I am using the MC9S08AC16 micro

The program I am working on makes the uP go to sleep (Stop3) about 20 seconds after power up, then it gets awaken by IRQ.

All outputs I am using then seem to change into inputs until all the registers are configured properly.

This is a problem because this means outputs are floating for about 2ms.

I have been using the CodeWarrior debugger, and I could see that pin E1 would be an input right after wake up/power up and set properly as an output only after this code:

 for( x = 0; x <= 13; x++ )    /* load registers 0 to 13 */
  {
     *((near byte *) x) = register_setup[x];
  }

I would like the uP to keep the same data direction after wake up as before (Note that the I/O direction is kept OK during sleep)

Can you help?

[bigmac]

Hello, and welcome to the forum.

What you have described would seem to suggest that you are using Stop2, rather than Stop3 mode.

During Stop2 mode, the current I/O output state is latched, but the registers must be re-initialised after wakeup.  This should not be required after wakeup from Stop3.

Refer to sections 3.6.1 and 3.6.2 of the device datasheet.

Regards,

Mac