I have been using cheap RFID chips for a while now, and I know they have many more unique identities than I will ever need in my wildlife application. But in writing up my work I need to quote the actual number. I can't find a straight answer anywhere, and am confused about whether one should try to work this out in hex or duodecimal or what. Can anyone help, please, with an explanation of how they get the answer?
My RFID tags are 12.25 × 1.93 mm glass capsules, 32-bit code, EM4001 protocol, from Shanghai Zangtian Electronic Co. Ltd. The de-ciphered codes take the form:
2 48 48 48 48 48 48 48 48 48 49 48 49 3 (for example)
Many thanks in anticipation.
48 48 48 48 48 48 48 48 48 49 48 49
That looks like the ASCII code for "000000000101", a 12 digit decimal number. If all digits are used in the range 0-9, then 1012 codes are possible.
If it is 12 hex digits 0-9 and a-f, then 1016 codes are possible, etc.
Without a spec sheet it is tough to tell - my first thought is it may be along the lines of a MAC address where half of the address specifies the vendor and half of the address specifies a serial number. There may be a vendor specific portion of the number you get back. I would think there should be some sort of data sheet from the manufacturer (although you might need to read Chinese to decipher it 
)
Thanks, guys.
I think that after all I have found the answer on this Sparkfun page. 32 bits of digital code allows numbers between 0 and 4294967295, inclusive. So there are in the region of 4 billion possible IDs. Decoding into ASCII and arranging the result into digit pairs seems to be just to make it more comprehensible to read.