Author Topic: EEVBlog 121GW Multimeter Firmware Details  (Read 18797 times)

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Offline 1anX

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Re: EEVBlog 121GW Multimeter Firmware Details
« Reply #75 on: August 11, 2018, 09:11:08 pm »
No problem for me. Did you rename the file to EEVBlog.bin?

Alexander.

Yep your right, it was my mistake after numerous updates I managed to forget to drop off the version number from the bin file  :palm:
 

Offline Zkronk

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Re: EEVBlog 121GW Multimeter Firmware Details
« Reply #76 on: August 12, 2018, 06:43:55 pm »
What is new in the 1.26 firmware?
The bin-file is available on the EEVBlog-site, but the change log in the PDF-manual is not updated :(
 

Offline firewalker

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Re: EEVBlog 121GW Multimeter Firmware Details
« Reply #77 on: August 12, 2018, 07:03:12 pm »
v1.26 is now on the website for download. We have not tried it yet, but UEi have said that it now logs the displayed data instead of the bargraph data. There should now be no noise on the logged data as per previous versions. Please try it and report.
Become a realist, stay a dreamer.

 

Offline firewalker

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Re: EEVBlog 121GW Multimeter Firmware Details
« Reply #78 on: August 15, 2018, 06:01:28 am »
Have anyone decoded the binary file with the calibration data?

Alexander.
Become a realist, stay a dreamer.

 

Offline tpw_rules

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Re: EEVBlog 121GW Multimeter Firmware Details
« Reply #79 on: August 15, 2018, 06:04:29 am »
Have anyone decoded the binary file with the calibration data?

Alexander.

Sure have. If you've got python 3 or above, run this script with the first argument pointing to the file.
 

Offline firewalker

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Re: EEVBlog 121GW Multimeter Firmware Details
« Reply #80 on: August 15, 2018, 06:19:20 am »
Thank you!!! <3 <3 <3

Alexander.
Become a realist, stay a dreamer.

 

Offline firewalker

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Re: EEVBlog 121GW Multimeter Firmware Details
« Reply #81 on: August 15, 2018, 06:26:43 am »
The offset number is directly added to the adc result? Is the function that involves the values read form the adc, the calibration data and the displayed number known?

Alexander.
Become a realist, stay a dreamer.

 

Offline tpw_rules

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Re: EEVBlog 121GW Multimeter Firmware Details
« Reply #82 on: August 15, 2018, 07:04:24 am »
The offset number is directly added to the adc result? Is the function that involves the values read form the adc, the calibration data and the displayed number known?

Yeah, it's all detailed in the reverse engineering. I suggest you consult that if you are curious because I'm too lazy to explain everything. But to put it in a sentence, bargraph = (ADC - offset) * gain, and screen = smooth(average(bargraph) - nonlinearity_corr), where average is the average of 8 or 16 bargraph samples, nonlinearity_corr is some nonlinearity offset calculated using some data tables and the listed coefficients in a manner that I don't entirely understand, and smooth is a rolling average that resets if the difference between samples is too large.

May I ask why you are interested in knowing all this?
 
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Offline firewalker

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Re: EEVBlog 121GW Multimeter Firmware Details
« Reply #83 on: August 15, 2018, 07:12:55 am »
I was wondering if it is possible to recalibrate offset by hand editing the calibration data. Because someone (Dr. Frank) mentioned that someone might have to complete and the full scale gain calibration in order the meter to save and accept the zero offset data. But this mean specialized equipment.

Alexander.
Become a realist, stay a dreamer.

 

Offline tpw_rules

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Re: EEVBlog 121GW Multimeter Firmware Details
« Reply #84 on: August 15, 2018, 07:18:59 am »
I was wondering if it is possible to recalibrate offset by hand editing the calibration data. Because someone (Dr. Frank) mentioned that someone might have to complete and the full scale gain calibration in order the meter to save and accept the zero offset data. But this mean specialized equipment

It would be possible. However, according to my knowledge of the firmware, the corresponding factor is saved before the G-END or OFF-E message is displayed. So you can just turn off the meter after offset calibration to skip gain calibration. But of course, the offset factor is used when calibrating the gain factor, so one would be advised to do gain as well. Maybe someone can work out the math to adjust the gain factor, and hand edit that in.
 
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