Hi Ian,
here is the schematic i was using.
Channel1 of the oscilloscope is used as trigger, I make led4 flashing during the communication with the master. Channel 2 is connected to the amplifier to measure the power consumption (actually i couldn't see anything at all).
The amplifier weren't connected to any other device.
At the moment the amplifier is no more connected to the board. The supply of the board works, i tried both the external supply and batteries and the leds turns on. I suppose the chip is still alive because the leds are connected directly to the MCU.
When i turn on the board all the leds turns on automatically and i can't make them flashing or turn them off or whatever bacause i can't flash the board. In fact if I try to load a new software with codewarrior just after debugging it appears an error (the text of the error is in my very first message).
I think that when connected all the circuitry and turned it on the MC13213 got an extra current and the internal memory of the MCU were erased.
I'm looking for a kind of hard reset as you can do with the personal computer, when yuo mess up the bios dafault impostation can be loaded by "clear cmos" procedure.
A professor of mine has the same idea...but it could be that I just make a "french toast" with the chip.
Thanks for your help
Tommaso