Author Topic: Upgrading/Unlocking Agilent Meters via EEPROM  (Read 13584 times)

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Offline gnif

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Upgrading/Unlocking Agilent Meters via EEPROM
« on: February 22, 2013, 07:17:09 PM »
Hi All,

Update: It has been confirmed that the U1732C LCR meter can be upgraded to a U1733C also!

I am opening this here as it is a more appropriate place to discuss this, please see the following message for the history of this:
http://www.eevblog.com/forum/buysellwanted/ex-demo-agilent-u1241's-for-sale-in-oz/msg194648/#msg194648

A quick synopsis:

The U1241A has a Atmel I2C EEPROM in it, that when the SCL and SDA lines are shorted on power up, the meter upgrades into a U1242A, as such I have just managed to dump the EEPROM and I am now proceeding to try to upgrade the thing :).

If anyone has a U1242A and is inclined to crack it open, it would be great if you could dump the EEPROM contents to make it easier to figure out how to upgrade this thing.

EDIT: This will also work for the U1241B as it is functionally identical.
« Last Edit: February 24, 2013, 04:20:53 PM by gnif »
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Offline gnif

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Re: Agilent U1241A to U1242A hack
« Reply #1 on: February 22, 2013, 11:41:23 PM »
I found it! I have all the features of the U1242A in my U1241A now!

Change byte 0x1e5 from 0x01 to 0x02!

This enables:
  J type Thermocouple
  AC Harmonic Ratio Measurement
  T2 Temerature Measurement
  T1-T2 Temperature Delta Measurement
  Scanning Temperature Measurement
  Data Logging
 

Edit: It might be just me, but it seems that the continuity tester is much faster to latch now also.
« Last Edit: February 22, 2013, 11:50:25 PM by gnif »
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Offline Lightages

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Re: [SUCCESS] Agilent U1241A to U1242A hack
« Reply #2 on: February 23, 2013, 10:27:47 AM »
Interesting find. Personally I find it curious that the U1241B exists at all. It costs $206 retail at one online retailer and the U1242B costs only $226, less than 10% difference.
« Last Edit: February 23, 2013, 12:38:22 PM by Lightages »
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Offline gnif

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Re: [SUCCESS] Agilent U1241A to U1242A hack
« Reply #3 on: February 23, 2013, 12:09:38 PM »
Agreed, but it makes me wonder how many other higher priced meters can be upgraded to their more expensive models which do have a larger price gap.
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Offline EEVblog

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Re: [SUCCESS] Agilent U1241A to U1242A hack
« Reply #4 on: February 23, 2013, 12:12:06 PM »
Nice find!

Dave.

Offline BravoV

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Re: [SUCCESS] Agilent U1241A to U1242A hack
« Reply #5 on: February 23, 2013, 04:01:52 PM »
Thank you ! Great finding !  :-+

Mind share the process how did you manage to find it ? If you don't mind of course.

Curious if this hack applicable to "B" version as well.

Now, the fun part, stalking great deal or bargain on NOS U1241.  :-DD
« Last Edit: February 23, 2013, 04:25:26 PM by BravoV »

Offline gnif

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Re: [SUCCESS] Agilent U1241A to U1242A hack
« Reply #6 on: February 23, 2013, 07:24:15 PM »
Thanks,

The B model is just a colour change according to the manuals, the website and the spec sheets, so it should work on it just fine also. If you are worried you can obtain a 2nd hand A model from Trio here. This is why I bothered to try to enable these features because I got the cheaper meter and the price difference wasn't just $20-30 for me, it was over $100.

The process was pretty simple, I did a tear down to inspect it and comment on its build on this forum. I noted that others had upgraded the firmware in other Agilent devices to fix firmware bugs, so I kept an eye out for an EEPROM when I had it apart. There was only one there, so as a quick and simple test, I shorted out the i2c lines to prevent the micro talking to it on start up, which presented an error, but was still functional. Checking the setup menu I found I had the additional options to configure, and all the other values were set to FF or FFFF, etc.. so the micro defaults values to FFFF when it cant read the EEPROM.

I then programmed a STM32 development board to dump & flash the EEPROM and had a look around in it. The data is pretty easy to see how it is segmented, calibration data, then device name, model and serial number, and after that the config space.

Since I knew that 0xFF was a good value to set to enable these features I started out by setting portions of the data to all 0xFF, powering on the meter and checking if it had the additional features.  If it didn't work, I reversed it, and tried another area, until it did work. Then I just repeated the process until I found the exact byte to change, and experimented with it's value.

A word of caution if you attempt this in any meter, make your EEPROM read only by pulling the write protect pin high before you start to be 100% sure you back up its contents before altering them, as the EEPROM also contains all the calibration data for your meter, and changing it will cause your meter to read things incorrectly.
« Last Edit: February 23, 2013, 07:26:15 PM by gnif »
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Offline fcb

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Re: [SUCCESS] Agilent U1241A to U1242A hack
« Reply #7 on: February 24, 2013, 02:11:00 AM »
somewhere in Agilent, and engineer is adding an encoded checksum routine to the EEPROM driver library....

Offline gnif

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Re: [SUCCESS] Agilent U1241A to U1242A hack
« Reply #8 on: February 24, 2013, 02:50:34 AM »
If they do it will only affect new units, as these are a OTP device.
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Offline vl400

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Re: [SUCCESS] Agilent U1241A to U1242A hack
« Reply #9 on: February 24, 2013, 03:45:38 PM »
Thanks for the mod  :-+ Works for U1732C LCR meter too, shows U1733C on boot and have 100Khz. Now to change the EEPROM  :)

Offline gnif

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Re: [SUCCESS] Agilent U1241A to U1242A hack
« Reply #10 on: February 24, 2013, 04:19:04 PM »
Thanks for the mod  :-+ Works for U1732C LCR meter too, shows U1733C on boot and have 100Khz. Now to change the EEPROM  :)

You are most welcome, it is awesome to know that it is not just applicable to my meter. If you let me know the byte to change and what to I will update the first post. I will now also re-title this thread as it seems that there might be quite a few that this can be done to.
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Offline EEVblog

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Re: Upgrading/Unlocking Agilent Meters via EEPROM
« Reply #11 on: February 24, 2013, 06:26:32 PM »
Probably a similar thing on the 1250 series 1270 series too!
But there is not a big difference in the price between the two models in each of these groups anyway.
Dave.

Offline BravoV

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Re: [SUCCESS] Agilent U1241A to U1242A hack
« Reply #12 on: February 24, 2013, 07:06:44 PM »
Thanks for the mod  :-+ Works for U1732C LCR meter too, shows U1733C on boot and have 100Khz. Now to change the EEPROM  :)

Wow, is that the same address and value ?

Offline gnif

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Re: [SUCCESS] Agilent U1241A to U1242A hack
« Reply #13 on: February 24, 2013, 07:23:31 PM »
Thanks for the mod  :-+ Works for U1732C LCR meter too, shows U1733C on boot and have 100Khz. Now to change the EEPROM  :)

Wow, is that the same address and value ?

From what he said I would suspect that he is just shorting the SCA and SDL lines to see if it will upgrade, that is why he said he just needs to update the EEPROM now.
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Offline ttp

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Re: [SUCCESS] Agilent U1241A to U1242A hack
« Reply #14 on: February 24, 2013, 09:39:19 PM »
I then programmed a STM32 development board to dump & flash the EEPROM and had a look around in it. The data is pretty easy to see how it is segmented, calibration data, then device name, model and serial number, and after that the config space.

This is quite interesting. How do you connect STM32 board to talk to EEPROM, I guess you don't remove/unsolder the EEPROM form original circuit?


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