MC9RS08KA2 Stop Mode not working.

[JohnFM]

I'm trying out the Stop Mode for MC9RS08KA2. The following is my code and it didn't seem to be working. The Stop mode supply current was about 1 ma all the time and never dropped even after the "STOP" instruction. Could someone tell me where the problem is?

void main(void)
{
    PTADD = PTADD | PTADD_PTADD0_MASK;

    PTAD |= PTAD_PTAD0_MASK; 

    SOPT |= SOPT_STOPE_MASK; 

    asm
    {
        STOP;
    }
    for( ; ; )
    { 
        PTAD &= ~PTAD_PTAD0_MASK; 
    }

}

Message Edited by John FM on 2008-06-03 03:38 AM

[JimDon]

Did you disconnect the BDM an reset the board?
Stop mode does not lower the current if the BDM is active.

[Braulio_Cespede]

You just help me solve one problem.

[JohnFM]

When I removed BDM and reset the MCU, the current dropped to 64 uA. It looked that stop mode was operating. However, according to the data sheet, the stop mode supply current should be 1 uA. I was using 3.3V as the supply voltage. There was nothing conected to the MCU except Vcc and GND. Is it possible to make the current drop further to close to 1 uA? Thanks!

John

[JimDon]

Are all the pins set to output?
Are there any modules you need to shut down?

I am not familiar with this chip, but I have gone thru this on other chips, and you have to read the fine print and also any errata.

[bigmac]

Hello John,

In addition to ensuring no floating inputs, make sure that the bandgap reference, the comparator and the LVI module are disabled in stop mode.  These modules each require many additional microamps.  If you are using the RTI module for wake up purposes, make sure it operates from the 1 kHz clock source, rather than the 32 kHz source.

If LV detection were to be enabled, it would require the level of current draw you are experiencing.

Regards,

Mac

[JimDon]

Also, make sure that you are just measuring the current to the mcu. In the end you need to know the draw of the board, but while you are trying to get the mcu code working, you need to know just the draw of the mcu.

In one case I had to lift a pin to measure the current of just the mcu, because the board was 4 layer and I could not find any other way to do this.