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Posts: 6
Registered: ‎01-21-2017

Sensor serial number convention

Hi All,

 

I am developing some applications to manage Silicon Labs I²C sensors, particularly the si705x temperature and si70xx temperature and humidity sensors. I was able to read the two 4 byte halves and check CRCs of some si7051s. Listing them in byte 0>3 order they are as follows:

 

85465100FFFF3333
A5465100FFFF3333
86465100FFFF3333
BD465100FFFF3333
A1465100FFFF3333
0C606200FFFF3333
FB5F6200FFFF3333
E85F6200FFFF3333
88465100FFFF3333
AA465100FFFF3333
32606200FFFF3333
8C465100FFFF3333

 

Is there a convention for the order of the bytes? Also, do different types of device have different extensions, e.g., does the FFFF3333 signify an si7051? If so, is there a list of device types and serial number characteristics?

 

Thanks in advance,

 

Rob

Posts: 61
Registered: ‎04-09-2015

Re: Sensor serial number convention

The only convention is SNB3 is 0x33 (Decimal 51 for Si7051). Other decimal values indicate other parts in this family per data sheet. the other bytes are just a serial number which we can use for tracking and there is no specific meaning to them.

Posts: 6
Registered: ‎01-21-2017

Re: Sensor serial number convention

Thanks for the reply.

 

Are the first 8 bytes are the serial number unique for every device (that is every Si I²C device) of just for every device with the same family code?

 

That aside, Is it safe to translate the serial number E85F6200FFFF3333 to E85F620033 (or 00625FE833) as a unique serial number for Si7051s.

 

Please excuse the pedantic nature of this query. I want to make a future safe system. My database of Dallas/Maxim 1-Wire parts is 17 years old and growing but they have become unusable for several reasons.

 

Rob

 

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Posts: 61
Registered: ‎04-09-2015

Re: Sensor serial number convention

We would have to sell a lot of parts before we would start using the other bytes, but it is possible we would use them so the only safe way to insure the number is completely unique is to use all the bytes except SNB3 as a unique identifier. It is extremely likely that the shortened number you suggest would be unique to you. That is, even if we started using the other bytes there is virtually no chance that you would purchase two parts with the same shortened number.