Hi Christian,

I use the microcontroller in 12 clk

I understand about the tolerance in the Baudrate. I have tried to lower the baudrate but then Flashmagic told me that it couldn't find the hexfile (???). On the other hand : I'm developing some software which will grow very large. About 40k. That takes a long time to upload at 9600 Baud.
So the only thing to do is to switch crystals