Hi,
I tried to write the ASCII characters for a Nokia 5110 to EEprom of an Attiny84 to free some memory. I used ArduinoISP on a Duemilanove and board Attiny84 1MHz. Every time I reprogrammed the Attiny the EEprom contained only 255's. I found that you can prevent the EEprom from being erased by resetting some fuses in the Tiny. On AVR® Fuse Calculator – The Engbedded Blog I checked the the field for EESAVE and left the rest Default. The following code was generated: -U lfuse:w:0x62:m -U hfuse:w:0xd7:m -U efuse:w:0xff:m
Next I started the command utility in Windows and typed (my ISP programmer was connected through com port 6):
avrdude -p attiny84 –P com6 -c stk500v1 -b 19200 -U lfuse:w:0x62:m -U hfuse:w:0xd7:m -U efuse:w:0xff:m
(for an explanation just type avrdude)
From then on the data in EEprom were conserved! After a day of try and error I wanted to share this information.
ArthurRep