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HP / Agilent 34401A hidden menu
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robert.rozee:
we really need someone with a scrap 34401A that they can experiment with. blown up front-end or ADC for instance, but that can still accept "DIAG:POKE ..." commands from the serial port and write to the EEPROM.

next, unsolder and remote the EEPROM, with a simple mechanism to switch over to reading the contents directly in an automated fashion after sending a POKE command. perhaps TiN (of xdevs.com) has such a parts unit available?

alas, i don't feel too inclined to mess too much with my own 34401A as it is the only one i have, and i do depend on it working and remaining in calibration!


cheers,
rob   :-)
Hydron:

--- Quote from: robert.rozee on September 25, 2022, 12:57:01 pm ---next, unsolder and remote the EEPROM, with a simple mechanism to switch over to reading the contents directly in an automated fashion after sending a POKE command.

--- End quote ---
No real need for this TBH, you can read it (probably a bit slowly) with the PEEK -1 command, and if you hold the processor in reset (ground pin 16) then you can read or write the EEPROM with an external programmer without any issues. Alternatively, if you have a logic analyser setup you could simply look for write accesses after sending a POKE command (it only writes to addresses it needs to update, and always reads immediately beforehand too, so you know exactly what gets changed).

If your programmer puts it's pins into high-Z mode when it's not actively working (as the AsProgrammer + FT232H setup I'm using seems to do) then you can actually just leave it connected, and only ground the reset pin when you need to flash the EEPROM.
Hydron:

--- Quote from: tv84 on September 25, 2022, 11:26:58 am ---If I understand correctly what you tested, these are the option bits:

Offsets: 0x11+0x12


--- Code: ---00 00 98 06 - Default
00 90 9C 06 - Store State + Temp + 10mA AC
00 10 98 06 - 10 mA AC
   |   |
   |   0001 - SCALE options in math menu
   |   0010 - ???
   |   0100 - Store State
   |   1000 - Default (?)
   |
   0001 - 10 mA AC
   0010 - Recall saved settings on power-up (set via SAVE menu item)
   0100 - ???
   1000 - Temp
--- End code ---

--- End quote ---
No luck with trying more POKE commands (other than POKE 27 can turn the TEMP option off, but seemingly not on), but I did try and set the other bits in the byte that turns on the SAVE menu, and one of them enables the scale option seen in the quick-start guide here (math menu): https://www.keysight.com/gb/en/assets/9018-04874/quick-start-guides/9018-04874.pdf

Had a quick test and scale factor seems to work (and even gives you up to 7 digits of output!)

Will update once I figure out which of the two bits it was. It's the LSB
tv84:
What about the 06 and the 9 in


--- Code: ---00 10 98 06 - Default
--- End code ---

Have you tried the bits in that byte and nibble?

I guess it could be part of the options map as (for example) an int32: 0x06981000
robert.rozee:
just a silly idea: perhaps the calibration lock needs to be turned off first to enable changing some of the option bits?


cheers,
rob   :-)
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