NanoVNA V2 Plus4 display flickers

[phlipse]

Got my new Plus4 today.
Unfortunately the display flickers very strong.

It gets less if you open up the menu.
The issue also appears when the VNA ist connected via USB.
Therefore I don't assume any issues with the voltage source.

Seems to me like a software issue.

[gabriel-tenma-white]

The LCD backlight is powered from the 5V rail in all V2 versions; is it possible to check if the 5V rail has noise on it? Maybe IP5305 issues?

[phlipse]

Tried it with my portable low cost oscilloscope and there was indeed some noise. Also the noise only appears when the device is powered on for some minutes. It also gets noticeably warm - is that normal?
Will measure it again with my scope at home.

Currently I cannot say if it is the "normal" noise from the boost converter (around 650kHz) or something else. The portable scope is not the best one. More like a wishing rod. ;)

[gabriel-tenma-white]

Try soldering a 100-1000uF electrolytic capacitor at the C712 position (beside port 2).

[phlipse]

Soldered 1000uF at C712. Now the flicker is almost gone. Although the noise on the power rail ist noticeably less.

Negative side effect: My old 850mA phone charger is not able to power the device anymore during power on. But that's ok, with a separate one it works fine.

[DiSlord]

Some display module on V2Plus4 flick, some not.
My module begin after some time of work (more better see on full dark baskground, example on enter to DFU mode)
This can be fix if set less frame on ST7796 init:

// Frame Rate
ILI9341_FRAME_RATE_CONTROL_1, 2, 0x50, 0x10,

Another module (i take it from old V2, and also check vs another module vs damaget touch) work good.
All old modules correct work vs unsolderd j1 jumper (use internal voltage regulator)
Also new module screenshots damaged (exist noise on read).

[phlipse]

@DiSlord only to get you correct: Do you not recommend to solder C712?

[dustinoff]

mine too. it is new 2 days ago. what is best solution?

[F1RVC]

I never had this issue till today after upgrading firmware to git-20210215-b884707.
Not a roblem of cold or hot neither USB . issue disapear when back to previous firmware , so look to be firmware issue.
Put a video inside file folder of [email protected]

is it the same flickering ?

Patrice.

[fiveangle]

I came here looking for solution to same flicker problem... V2+4 bought from HCXQS group on Tinde ("official seller") just weeks ago so seems this issue hasn't been fixed in the last year.

I am willing to downgrade display framerate but the FW version on the unit is "git-20210538-412578c" and it's nowhere to be found here ?

[nanovna]

fixed in firmware 20210726 https://nanorfe.com/downloads/20210726/nanovna-v2-20210726-v2plus4.bin

[fiveangle]

fixed in firmware 20210726 https://nanorfe.com/downloads/20210726/nanovna-v2-20210726-v2plus4.bin

Thank you for that fix update, but the firmware you link to as "nanovna-v2-20210726-v2plus4.bin" reports as "git-20210530-412578c with build time Jul 26, 2021 10:55:59. The prevoius version as delivered from the Tindie vender was the same exact reported version but it had a build date of Nov 6 instead of Jul 26.

Where is the code for the fix and I can just compile the flicker fix myself ? I'm a bit worried about installing random FW that aren't what they say they are.