SCI and PLL imcompatiblity on MC9S12A256B

[gautier]

Hi,

I'm surprise, I'm use two boards: one with a MC9S12DP512 and the other with a MC9S12A256B.

I have make a program to use the SCI and PLL module of the microcontroller.

The program work fine on the MC9S12DP512 but don't run on the MC9S12A256B.

if I use only the PLL module it's OK.

If I use only the SCI module it's OK

But if I use the twice it's not OK

Can you help me to solve this problem??

[EMontanez]

With SCI communication you have to maintain within a +/- 3% error of your determined baudrate in order for communication to be executed properly.  My best guess is that the clock source that you are using to feed your PLL on the A256B board is marginal in relation to the DP512 board. I am assuming here that you are using the same crystal configuration on both boards.

I suggest you check your clock source. 

[gautier]

Your analyse is right.

I have unsolder the crystal of the 9s12DP512's board (16MHz) and replace the 9S12A256's board (20MHz) and that's running.

Thanks a lot for your help.