Hacking the Siglent SDM3055 Bench DMM

[alexvg]

During my SDM3055 reverse engineering... I've got 2 questions to you ?

Would you agree to pay a small amount for a new SDM3055 software (and maybe for the SDM3045) ?
http://www.pixule.com/39863606081_would-you-agree-to-pay-small-amount-for-new-sdm3055-software-and-maybe-for-the-sdm3045.html

Would you like to improve your SDM3055 by adding a some options ? (The SDM3045 may be compatible with these options.)
http://www.pixule.com/398636486944_would-you-like-to-improve-your-sdm3055-by-adding-some-options.html

Thanks for your help !


Hi,

I'm working on a hack to show more digit to the Siglent SDM3055
I've got a source voltage of 2.5V (not a reference voltage)

Original : 240 000 points / 5 1/2 digits


First hack result : 2 400 000 points / 6 1/2 digits


The hack does not work correctly but give interresting result.
To be continued.

[tv84]

 

Alexia, as requested. 2 of the latest app versions attached. Good luck!

[alexvg]

New results with 7.5 digits
The calibration data are not currently loaded :

[Mr. Scram]

Nice experiment! Not to rain on your parade, but are these numbers relevant? Do we know whether the 6.5 digit versions maybe have cherry picked or simply better references? I'm asking because many meters can show more digits but it's generally noise. Don't let it discourage you though and be sure to hack on!

[alexvg]

I've noticed some mistake into the code :
A real value of 1.499995 is displayed 1.4999 instead of 1.5000.

But a value of 1.4999995 is displayed 1.5000. It's because the rounding is done with a value of 5.0x10-7

[coromonadalix]

I would love to see this hack against a AC / DC / Ohms  calibrator ??

[tautech]

Not to rain on your parade, but are these numbers relevant? Do we know whether the 6.5 digit versions maybe have cherry picked or simply better references?

Yes of course measurement stability can be questioned as SDM3065X uses the better LM399 reference.

[coromonadalix]

Could the 3065 and 3055  share the same design, minus the reference quality ?? 

Q: The hacked firmware, does it come from the 3065 ??

[tautech]

Images from SDM3000 series thread
https://www.eevblog.com/forum/testgear/siglent-new-bench-dmm-sdm3055/

SDM3045X


SDM3055


SDM3065X

[alexvg]

Could the 3065 and 3055  share the same design, minus the reference quality ?? 

The SDM3065X uses a LM399H (0.3ppm/C with 20ppm/1000h and 7uV noise) voltage reference and AD7175-2 "B" A/D (up to 24 peak-to-peak bits and 24 effective bits at 5 to 16 SPS).
The SDM3055 uses a MAX6325 "C" (0.5ppm/C with 30ppm/1000h and 1.3uV noise) voltage reference and AD7190 "B" A/D (up to 22.5 peak-to-peak bits and 24 effective bits at 4.7 SPS).
The SDM3045X uses TI REF5025K "High grade" (2.5ppm/C with 100ppm/1000h and 3uV noise ) and AD7190 "B" A/D (up to 22.5 peak-to-peak bits and 24 effective bits at 4.7 SPS).

Edit 2019-08-18
Difference vs SDM3055 :
- SDM3065X uses a separate power supply
- SDM3065X uses a LM399H voltage reference and a higher resolution ADC
- SDM3045X uses lower grade components but with a SDM3055 design (or SDM3055X-E PCB)

I suspect the SDM3055 could have a better ADC (see un populated U503 SSOP28) like ADS1256 (seems to be compatible)

Q: The hacked firmware, does it come from the 3065 ??

I'm only using the original SDM3055 firmware.

[tv84]

If anyone with a 3045X wants to test the 3055 in his DMM, I can easily prepare an .ADS.

BUT, no responsibility for my side.

[tautech]

I'm working on a hack to show more digit to the Siglent SDM3055

To be continued.....................

And she busted it ! 

PM pleading for help ...............
And returned.

[BillB]

Well, that escalated quickly!   

[alexvg]

I've done some bash correction to correctly use XML calibration file.
Now the value displayed is correct and the result is very interresting.

I'm investigate to display digits with a little lower font size.

With the input shorted to the ground :

[alexvg]

How to test the sdm-mod ? (only with the latest 1.01.01.19 firmware)

Step 1
Plug a formatted FAT32 USB Key (I use 4GB) into the SDM3055

Step 2
Connect to telnet (username:root, password:ding123)

Step 3
Backup all Siglent data into the USB key :
"cp -R /usr/bin/siglent /usr/bin/siglent/usr/mass_storage/U-disk0/"
After copying, unplug the USB key

Step 4
Plug the USB key into your computer
Copy "sdm-mod.app" into the "/siglent" of the USB key
Unplug the USB key

Step 5
Plug the USB key into the SDM3055 and go to telnet
Stop the current sdm.app application : use "ps" to list all application PID and kill the "./sdm.app" PID.
Generally it's the PID 550, you could kill it with command "kill 550"

Step 6
Prepare and run the mod
"mkdir /usr/bin/siglent/usr/mod"
"cd /usr/bin/siglent/usr/mod"
"cp -R /usr/bin/siglent/usr/mass_storage/U-disk0/siglent/ /usr/bin/siglent/usr/mod/"
"cd siglent"
"./sdm-mod.app"

Step 7
To stop sdm-mod.app, just press "Control C".
Restart the device to return to normal operation.

Step 8
To remove the mod folder
"rm -r /usr/bin/siglent/usr/mod"

Code: [Select]

sdm-mod.app 20190812 v01
SHA1 : 85ceab5b27570de364ab127d0c67a7deb17903ab
SHA256 : d26b360d6db9a89b058b4d44a2116c546b492e402df37fa1d491276a415fd5d0

Features
- Add 2 digits (7 1/2 digits)

Drawback
- On some menu the sign and/or the last digit is not display correctly


[alexvg]

I'll post later 2 other versions :
- sdm-mod.app with only one additionnal digit
- sdm-mod.app with two additionnal digits and some special text display (if it's work !!!)

I've not currently found the solution to change the font size.
It takes very long because my ARM debugger does not work...

If anyone know a solution to do a remote debugging of an ARMv7 GDBServer using Windows (or Debian)...

If you have a voltage reference, could you post your result ? (I use the BARmeter menu to display all digits)

[tv84]

If anyone know a solution to do a remote debugging of an ARMv7 GDBServer using Windows (or Debian)...

IDA?

[Zorc]

  Very cool you've got this far!
Interesting to find out how usefull this actually is!
I don't have a benchtop DMM but maybe in the future this might be a model I would consider buying (whenever I decide I really 'need' (read: want to have) one to supplement my handheld multimeters)

[coromonadalix]

Has it been compared against a precision source  ??,  nice to have more digits,  are they worth displaying ??

[alexvg]

Has it been compared against a precision source  ??,  nice to have more digits,  are they worth displaying ??

I would like to know if additionnal digits are usefull or not.
The only thing I could say, there are an internal rounding error.

IDA?

I've tested IDA but it does not support this application and/or GDBServer integrated into the SDM3055.

[tv84]

I've tested IDA but it does not support this application and/or GDBServer integrated into the SDM3055.

What about via JTAG?

[alexvg]

Here's the 6 1/2 digits version :

Code: [Select]

SDM 3055 m1-1908-01

Feature
- Add 1 digit (total of 6 1/2 digits or 2 400 000 points)

SHA1
cb89541b22959c8cdae8a7a917b29ca7042d4bcf

SHA256
73bef60988a4b4ec684132795c0f6b99bb4fcf4d4e1824f0acad414d9f9f64cb


How to test the sdm-mod ? (only with the latest 1.01.01.19 firmware)

Step 1
Plug a formatted FAT32 USB Key (I use 4GB) into the SDM3055

Step 2
Connect to telnet (username:root, password:ding123)

Step 3
Backup all Siglent data into the USB key :
"cp -R /usr/bin/siglent /usr/bin/siglent/usr/mass_storage/U-disk0/"
After copying, unplug the USB key

Step 4
Plug the USB key into your computer
Copy "sdm-mod.app" into the "/siglent" of the USB key
Unplug the USB key

Step 5
Plug the USB key into the SDM3055 and go to telnet
Stop the current sdm.app application : use "ps" to list all application PID and kill the "./sdm.app" PID.
Generally it's the PID 550, you could kill it with command "kill 550"

Step 6
Prepare and run the mod
"mkdir /usr/bin/siglent/usr/mod"
"cd /usr/bin/siglent/usr/mod"
"cp -R /usr/bin/siglent/usr/mass_storage/U-disk0/siglent/ /usr/bin/siglent/usr/mod/"
"cd siglent"
"./sdm.app"

Step 7
To stop sdm.app, just press "Control C".
Restart the device to return to normal operation.

Step 8
To remove the mod folder
"rm -r /usr/bin/siglent/usr/mod"

[alexvg]

If anyone with a 3045X wants to test the 3055 in his DMM, I can easily prepare an .ADS.

BUT, no responsibility for my side.

Never try to use SDM3045X or SDM3065X into the SDM3055
- The SDM3065X app program have an error loop
- The SDM3045X app program seems to work, but there no value on the display.

I'm currently testing a modification : I've removed the 0.5uV add/sub.

Edit: If you want to use the initial mod version I've posted (7 1/2 digits), You need to use the stat menu to display all digits and sign without any artefact.
I've noticed after a measurement of a battery (around 8V), using 20V range, there's a +/-20uV variation. This corresponding to a +/-2uV at the input of the ADC (with its 2.5V reference).
This seems to be very good.

[alexvg]

I've add 2 little heat sink on voltage reference and ADC and I removed the fan.
The result is interresting (using 200mV range, short-circuit on the input and more than 4000 samples) :
- Previous noise result was 1.75uV
- Now the noise is reduced to 1.34uV (difference between min/max) and standard deviation is 0.207uV

I've mesured a -90dB noise into the 5V line... Why Siglent integrated the analog/logic power supply on the same board ? (except for lowering cost).
I'm thinking about adding a pre-rectifier/filter/regulator, changing the 5V regulator and probably changing the voltage reference to the LTC6655B-2.5 (if I could access to an excellent reference voltage).

I've received a AD584LH voltage reference, I've measured 20K samples at 2.5V with 20V range :
- 78uV span (+/-39uV)
- 11,1uV standard deviation

I think the SDM3055 seems to be more interresting than I though first (It only need some modifications to be more better).

[alexvg]

I've tested IDA but it does not support this application and/or GDBServer integrated into the SDM3055.

What about via JTAG?

I've successfully running the remote debug using Texas Instrument Code Composer Studio...