开云体育

I have a NanoVNA-H4 which has been working for months. Today I needed to test a broadcast band filter and when I try to enter any number on the number screen (for setting stimulus start/end etc.) the screen goes fully white. All other functions of the NanoVNA seem to be working fine, only the touchscreen is bad. I've re-done the touchscreen calibration (which works normally), saved it, and done the touchscreen test which doesn't indicate any problem -- I can drag the guitar pick up, down, right, left, and diagonally in any part of the screen and it looks fine.

I see in searching for this problem many people have had touchscreen issues, but none just like this. I will try flashing a different version of the firmware (this is Dislord's 1.2.40) and following that if needed I'll disassemble the case to inspect the ribbon cable. Any other suggestions?

I can't get the device to connect with a Windows computer in DFU mode. I can connect in normal mode with COM4. As soon as I put the device in DFU mode it disconnects and COM4 disappears from Device manager. I tried with both nanoVNA-App and STM32, both act the same.

As it should! Dfu is *NOT* a COM port, and requires it's own driver which is provided with the app of your choice.

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Sent from my Android device with K-9 Mail. Please excuse my brevity.

Before re-installing firmware, I would try a 'clear config' (under expert settings).
That will help reset internal parameters, in case something amiss there is affecting this.

Regarding new firmware, when you put the nanovna in DFU mode, it will remove the com port, and a new entry will appear in device manager under the 'Universal Serial Bus Controllers' or 'Universal Serial Bus Devices'. It will either be titled "STM Device in DFU Mode" or "STM BOOTLOADER".

If it says "STM BOOTLOADER", use STM32CubeProgrammer to update the firmware.
If it says "STM Device in DFU Mode", use nanovna-app or DfuseDemo to update the firmware.
Otherwise it won't connect. Unfortunately the drivers are not the same for the different applications.
Stan KC7XE

I discovered the problem -- it is my SD card. If I remove the SD card the NanoVNA operates normally (without changing firmware). I tried a different SC card and the problem returned. So, I need to look again at my SC card slot I soldered in last year. It's been working since then up to now. Maybe something came lose, or some particle fell in and shorted something out.