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LeCroy Probus reverse engineering
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bson:
I think 38 is the input coupling and impedance, while while sometimes 39 is only the coupling.  Not sure why both would be there, especially since 39 is often merely the two first characters of 38.  Some probes only have 38.  It seems a bit helter-skelter.

DA18000AC.bin :
38 09 41 43 20 35 30 15 0a   'AC 50
'
39 05 41 43 0a   'AC
'

DA1820A.bin :
38 0b 45 78 74 65 72 6e 61 6c 0a   'External
'
39 05 45 78 0a   'Ex
'

OE695G.bin :
38 08 58 58 58 6e 6d 0a   'XXXnm
'

PP090.bin :
38 06 37 35 ea 0a   '75\xea
'

ZS1000.bin :
38 09 44 43 20 31 4d 15 0a   'DC 1M
'
39 05 44 43 0a   'DC
'

I wonder what those 0xea and 0x15 bytes are for, but I'm sure they serve some purpose.
I assume if it says DC or AC the coupling is locked.  Same if it has an impedance.
ollopa:

--- Quote from: bson on May 30, 2024, 06:34:10 pm ---Are you sure type 04 is a serial number?  It looks like at least sometimes it's an ascii version number, for the newer probes.  Maybe for older probes it's a binary version number?

ZD1000:
04 06 41 30 30 31    'A001'

ZS1000:
04 06 31 34 38 32   '1482'

ZS2500:
04 06 41 30 30 35   'A005'

AP020:
04 06 96 18 00 99 

Maybe 99 is 1999 and they changed the encoding at Y2K?  :P

--- End quote ---

I'm not saying that it's an actual unique serial number, but it is in the "serial#" field of the probe info.
Also note that I don't have real dumps from actual probes for all of these, some are EEPROM values used for simulation so they may have SN values with some other meaning to the firmware developers.

ollopa:

--- Quote from: bson on May 30, 2024, 07:02:35 pm ---I think 38 is the input coupling and impedance, while while sometimes 39 is only the coupling.  Not sure why both would be there, especially since 39 is often merely the two first characters of 38.  Some probes only have 38.  It seems a bit helter-skelter.

--- End quote ---

Look at the attached picture and you will see that there are two places in the UI where the coupling appears, one location is just 2 bytes and the other is the longer selection string.  This may be a clue as to the reason why, but I'm not sure.  The 0x39 tag doesn't seem to do anything to the UI but if I change the 0x38 tag in the ZS1000 EEPROM then it does change the input channel coupling selection between DC and AC coupling.  And if you look at the second screenshot I can change the text in the UI to something ridiculous like 5GOhm.

It could be that 0x38 is just the UI label and 0x39 controls the hardware setting, with 0x39 defaulting to DC 1M when not specified.


--- Quote from: bson on May 30, 2024, 07:02:35 pm ---I wonder what those 0xea and 0x15 bytes are for, but I'm sure they serve some purpose.

--- End quote ---

They do.  0xEA is the omega symbol in the extended ASCII table and 0x15 appears to be an alias. 
ollopa:
One more experiment.  Look what I did by changing 0x38 and removing 0x39.  I can set arbitrary text for the coupling UI
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