My notes based on Vtech's post (and other's work). There were a couple of little things I was not sure of, so I cover them here in case others have the same questions. I'm grateful for the hard work of others making this possible. ( My unit DG821 just bought on current --July 2020-- 'clearance' $251USD was on version 1.08 )
Since mine came with version 1.08 already, I could skip to step two on Vtech's list.
2. Prepare a "magic" USB stick. Format USB stick as FAT32 (stick MUST BE BIGGER than 1GB). Open it in HxD editor as LOGICAL DISK (not physical disk - I did that mistake) Tools->Open Disk (uncheck "open as readonly"). Jump to sector 2000000 (sector field is at the top right corner). Enter value manually or use "Paste write" in edit menu (Ctrl+B). Magic value: 0B0A3B2E5F4CECBEI did this from Windows 10. For good measure I DISKPART cleaned the drive, Disk Manager simple volume and formated it FAT32. Used Tools menu in HxD64 to open drive H: (your dive will/may be different. Make sure you have the correct one selected) (16gb Sandisk Cruzer in my case) went to sector offset 2000000 and manually entered the hex string. File menu save. Exited HxD64 and used Windows File Explorer to eject the disk safely. Note, there were no other files on the disk, you do not need to write any image onto the file. Just make those hex changes to the sector offset.
While the DG821 was running, I inserted the usb thumb drive. A "waiting' popup appeard and the USB icon appeared into the upper right.
3. Insert the magic stick into DG (make sure it is recognized and USB icon is shown) and connect the instrument with the computer (using USB A-B cable and downloading Rigol's bloatware UltraSigma is the easiest way). Open SCPI command panel, check communication by issuing *IDN? command (use Send & Read). Send command :PROJ:SN DGxxxxxxxxxx with your correct SN number noted in step 0 (use Send command, DO NOT USE Send & Read). Verify if it worked by sending another *IDN? command - it should report back with correct serial number. Now send command :PROJ:MODE DG992. You can disconnect the instrument from PC and remove USB stick.I connected it to the PC and used the SCPI Command function of Ultra Sigma.
(This text is from ultranalog's post with my notes())
-> *IDN? (Use Send and Receive button)
<- (Return Count:55)
Rigol Technologies,DG821,DG8A123456789,00.01.08.00.01
-> :PROJ:MODE DG992 (Send button only)
-> *IDN? (Use Send and Receive button)
<- (Return Count:55)
Rigol Technologies,DG992,DG8A123456789,00.01.08.00.01
I removed the cable.
I had to do a power off at this point. I powered back on the unit and the screen text background changed to red/orange colors and I could see the icon for channel two.
SEE TV84's post below: I did not need this step:Step 4. Finish_Upgrade_2.04.zip is only needed if your purchase version was higher than v1.08.
4. Download tv84's "Finish_Upgrade_2.04.zip" from this post: https://www.eevblog.com/forum/testgear/new-rigol-16-bit-function-generators-dg800900-series/msg3119264/#msg3119264
Put this GEL file on USB stick, plug into DG and confirm update when popup shows.
Unit will reboot on it's on at this point.
I copied and overwrote tv84's patch with the larger factory firmware. I turned the unit off and let it boot again before doing final upgrade. 5. Download official 2.04 firmware from Rigol: https://int.rigol.com/Public/Uploads/uploadfile/files/ftp/DG/软固件/SardineII(ARM)Update-v00.02.04.00.00.rar
No logging in required
Put GEL file on USB stick (delete the previous one), upgrade DG and enjoy
Serial number should be kept and model should be DG992.
All credits go to tv84, bulba99, evgbog and others who helped to create this hack!I inserted the USB while the unit was running. It was in 'waiting' mode for a while, be patient. Select yes to the update prompt (don't forget that it is simple as using the touch screen). Then the unit automatically rebooted and started writing the firmware flash space. I removed the USB after the screen went black during reboot. I powered off once again when it was finished and powered up I'm left with this success:
(I can remove that little while option cap)
(soapbox)
I am pleased. While currently I understand (based on other's tests) the unit is more on par with DG952, that is more than fine with my use. If DG952 performance, I gained a second channel, extra memory, and double the signal rate/sample rate.
Currently in the states the DG821 is a couple dollars cheaper than the DG811. I'm assuming they are the same hardware, but at least in the case of the DG821 you know it factory tested at 25Mhz. Ethically, I feel I'm in a gray area with this weird software limited hardware. But, I'm not using mine for profit so I don't see it much different than performance tuning 'unlocks' on a car. Rigol did not lose any money in my case. I would have adapted my personal learning projects to the equipment I could afford (DG821) because I did not have the budget for more. In a way, this makes me like their product better.
(/soapbox)