Scale EEPROM? - Page 1
Forum section: electronics / general

author: vlad777
author_rank: Frequent Contributor
timestamp: December 22, 2013, 09:36:02 pm
content: I disassembled two different (weight) scales fromtwo different manufacturers and apart from COB theyboth contain 24C02 EEPROM.What do you think is in these eeproms?Many thanks.

author: Len
author_rank: Frequent Contributor
timestamp: December 22, 2013, 09:45:17 pm
content: Calibration data?

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: December 22, 2013, 09:48:38 pm
content: Calibration and probably also features - kg/pounds etc. the COB will be a mask rom, so having external ee allows the same one to be used for different models

author: vlad777
author_rank: Frequent Contributor
timestamp: December 22, 2013, 10:27:17 pm
content: Could it be that the COB is uC and eeprom contains firmware?(apart from calibration)

author: tom66
author_rank: Super Contributor
timestamp: December 22, 2013, 10:37:00 pm
content: I would doubt it. Any firmware is basic enough to fit in mask memory. If there is any. A basic scale wouldn't need much more.

author: vlad777
author_rank: Frequent Contributor
timestamp: December 22, 2013, 10:48:20 pm
content: What about calibration?Is it programmed once or does the scale recal on it's own?

author: mikeselectricstuff
author_rank: Super Contributor
timestamp: December 22, 2013, 11:02:18 pm
content: Quote from: vlad777 on December 22, 2013, 10:48:20 pmit will be a factory cal to correct for cheap sensor and electronics

author: GreyWoolfe
author_rank: Unknown
timestamp: December 22, 2013, 11:09:11 pm
content: Back in New Jersey in the 80's when I worked for Nabisco as a salesman, I remember seeing the scales in he grocery stores with calibration stickers on them. I seem to remember the scales had to checked for accuracy on a yearly basis. Not sure though if the scales then were purely mechanical or had electronics in them.

author: JoannaK
author_rank: Frequent Contributor
timestamp: December 22, 2013, 11:31:05 pm
content: Quote from: mikeselectricstuff on December 22, 2013, 11:02:18 pmI have even seen some cheapish chinese kitchen scales that are user re-calibrable. Just add 1KG atop and press some button combination mentioned in manual.

author: vlad777
author_rank: Frequent Contributor
timestamp: December 22, 2013, 11:41:55 pm
content: Quote from: JoannaK on December 22, 2013, 11:31:05 pmThanks,I didn't know that.Sounds like a good idea.

author: Zero999
author_rank: Super Contributor
timestamp: December 23, 2013, 12:21:11 am
content: Quote from: mikeselectricstuff on December 22, 2013, 09:48:38 pmI notice you've mentioned features. Do you mean it might be possible to hack it to a higher specification, like a Rigol 'scope?

author: SeanB
author_rank: Super Contributor
timestamp: December 23, 2013, 06:28:09 pm
content: Typically the one chip solution is capable of working from 1kg to 300kg, depending on the load cell and mechanical base used around it. The ADC on there is typically a 14 bit unit, using digital smoothing and a lot of samples to get a stable reading. The eeprom will typically have a set of values for display type ( no of digits, decimal location, units and other annuciators), full scale resolution ( the load cell gives about the same raw digital reading from zero strain to max design strain), base count units ( the typical unit will do 5g intervals while the sensor result typically will be 2g5 or so but will drift a little), zero mass value (the unloaded mass of the weight platform and mechanical parts on the knife edges) and finally a scale value set ( one or more breakpoints) used to trim the conversion from digital ADC data to displayed data.Typically you turn it on and level it, leave it to warm up for a hour or so then put it in cal mode ( can be a switch on the board, a button combo or a plug in dongle), zero it and then place a reference masspiece on and adjust the display to show the calibration mass. Some you do at multiple points to get the multipoint slope used to linearise the unit. I have one that requires a preset mass, so I have to use a combination of mass references to get the closest match, it is out by about 3mg then.

author: SpikedCola
author_rank: Newbie
timestamp: June 13, 2025, 09:43:18 pm
content: Necroing an old thread here, but I recently had to fix a scale that had corrosion damage due to water. Just the SDA/SCL pins of the EEPROM were damaged. It has a COB and 24C02, and not much else. I exposed the pins, dumped the EEPROM, and programmed a new device.I thought you might be interested in what was in the old one:Code:38 24 8B 16 8D 16 5F 0522 E5 2F C4 FF FF FF FF82 33 0A 01 3F FF FF FFFF FF FF FF FF FF FF FFFF FF FF FF FF FF FF FFFF FF FF FF FF FF FF FFFF FF FF FF FF FF FF FFFF FF FF FF FF FF FF FFFF FF FF FF FF FF FF FFFF FF FF FF FF FF FF FFFF FF FF FF FF FF FF FFFF FF FF FF FF FF FF FFFF FF FF FF FF FF FF FFFF FF FF FF FF FF FF FFFF FF FF FF FF FF FF FFFF FF FF FF FF FF FF FFFF FF FF FF FF FF FF FFFF FF FF FF FF FF FF FFFF FF FF FF FF FF FF FFFF FF FF FF FF FF FF FFFF FF FF FF FF FF FF FFFF FF FF FF FF FF FF FFFF FF FF FF FF FF FF FFFF FF FF FF FF FF FF FFFF FF FF FF FF FF FF FFFF FF FF FF FF FF FF FFFF FF FF FF FF FF FF FFFF FF FF FF FF FF FF FFFF FF FF FF FF FF FF FFFF FF FF FF FF FF FF FFFF FF FF FF FF FF FF FFFF FF FF FF FF FF FF FFYour guess is as good as mine!