On Fri, Dec 20, 2024 at 12:04 PM, Wevie wrote:
I will do the raw copy of the disk in the upcoming days, will update this
topic for sure.
I was under the impression that calibration coefficients are in nvram too on
8000 series. That explains at least the issue with lost calibration parameters
due to drained battery's..
It was 4+ years last time I looked at it so take the following comments with a grain of salt. Some calibration data is stored in a directory "CalConst". I think those are the ones scope can figure out itself and save. File names are "1" to "16" but "4" is missing. Bank 4 has the EEPROM data for things scope can't figure out itself such as the reference voltage. During boot of my scope bank 4 is loaded from EEPROM:
0x16987e0 (tShell): Reading 280 bytes of service cal data from EEPROM[0] into 0x2d1a240
0x16987e0 (tShell): nvMem_read succeeded
0x16987e0 (tShell): Reading 66 bytes of service cal data from EEPROM[280] into 0x2d1a300
0x16987e0 (tShell): nvMem_read succeeded
It is possible that after scope boots these values are in NVRAM and by saving NVRAM you are also saving the factory data. However, it has to be somehow mapped to EEPROM if EEPROM is lost. My scope came "broken" (Tek cal reject, input relays were bad) so I don't know if some of the boot scripts were modified and EEPROM is not usually loaded. If someone with a TDS7xxx can also paste their log file we can tell. In any case it looks like EEPROM is storing some useful information. Lost NVRAM data will erase some calibration coefficients but here are hooks in vxWorks to read and write calibration constants from the disk "calConst" directory so even if they are lost they may be recovered (assuming they were written properly in the first place) but not bank 4 which is on EEPROM.
Solution may already be there in many pages of eevblog discussions.
Ozan
