If I have an EEPROM integrated circuit but documentation is not available for it, how can I find out how much memory is available to me? My first thought was to write some distinct bytes to the first several sequential addresses and then loop through the memory reading each byte until I read my distinct bytes and count how many bytes exist between reading the distinct bytes the first time and the second time. But then I realised that my unsigned data type could be too small and wrap from its largest value back to zero before the last address in the EEPROM was actually reached. Any software or hardware tricks to learn this information about an unidentified EEPROM integrated circuit would be very much appreciated.
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Hi Dillon, you say "documentation is not available"..... maybe this is a stupid question, but have you tried google the type number denoted on the chip ? There are zillions of data sheets online for chips ! – Goodies Apr 08 '20 at 10:22
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This has ended up being more of a theoretical question for me, but in some cases it may be impractical to look up the documentation. For example if someone had obtained some lot of assorted EEPROM chips and it was faster to hook each one up to some circuit and run a program rather than read the number on each individual chip and look up the documentation for each one. Or perhaps the part number is not legible. – Dillon Apr 13 '20 at 00:53
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My solution to this problem ends up being pretty close to my theory stated in my question, where I write some recognisable pattern of bytes starting at byte zero of the EEPROM. I then loop through the EEPROM memory, starting at byte zero, and keep track of how many bytes exist between the first time we read our "recognisable pattern of bytes" and the second time. To ensure that I don't read from byte zero a second time before reading every other byte in the EEPROM memory once (due to our counting variable being too small to count up to the size of the EEPROM memory), I then increase the size of my counting variable datatype to be able to count to a higher number if needed. If the number of bytes between the first read of the "recognisable pattern of bytes" and the second is the same with the two different sized counting variable data types, then I know that I have found the correct size of the EEPROM in bytes.
Dillon
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