When PSEN is hold down during Reset and
after Reset the Serial Download is in
Progress.
Otherwise PSEN is not connected.(high)
When PSEN ist hold down and the chip is
in Serial download mode the hole flash
is erased and ready to programm new.
You can measure with a mA meter a higher
current consumption, that indicates this
mode.I use the ADuC812 2 year ago and i
had with some chips the same problem.
But it was the Downloadprogramm it does
not work under Windows (95/98)correctly.
Open a DOS-Window at first when you startup your computer and run the download programm.
Or run it under real DOS.
Dont forget on Data EEPROM Page 160 are
some security bits.Never write to this
bits the ADuC is dead for your update.
But i can erase the chip with all security bits !