Nextion displays and memory sieves

M0RVB

You know the phrase 'memory like a sieve'? Well, that's mine. I just received a 3.2" Nextion display via Aliexpress which arrived after only a few days from China. This was to be a display for the M17 hotspot. But there were a few unexpected hurdles!

First off, I could not remember the connections from the GPIO pins of the Pi to the Nextion. It's actually really easy, pins 4, 6, 8 and 10,  but it took me an age to find that information on the web. Onthe Pi 4B the GPIO pins are numbered from the top (the opposite end from the USB and Ethernet connectors) with odd numbers on the left and even on the right. There are plenty of diagrams on the web. So pin 4, which is +5V is the second one down on the right, pin 6 is next down and 0v, then pin 8 which is transmitted data from the Pi, and pin 10 is received data to the Pi. The Nextion display came with a cable with a connector for the display. This has red for +ve, blue for data from the display, yellow for data to the display and black for 0V. So this is what I ended up with:

ItemGPIO pinNextion wire
+5V supply to Nextion4Red
0V6Black
Data to Nextion8Yellow
Data from Nextion10Blue

With all that done (I say all, it's just 4 wires!) the screen came on when the Pi was powered up. The screen displayed some default moving imagery but nothign from WPSD.

I had vague memories now that you need to stop the Pi running a login shell for the serial port. The Pi is running Bookworm, options may differ but running sudo raspi-conf and selecting 3 Interface Options and then I6 Serial Port allows one to select No for login shell and then Yes for enabling the serial port hardware. This is a vital step I had forgotten.

I set WPSD to use the attached display as /dev/ttyAMA0 and the G4KLX layout. Still nothing from WPSD.

More searching all over the place and I re-learned another vital step I had forgotten - you need to install code directly onto the Nextion screen which turns it into a display able to take data fed from the hotspot. The screen has an SD card slot specifically for this.

More searching and I found some Nextion files from G4KLX as a starter. There is a set of tft files which are the code for the Nextion and need to match the screen - NX4024T032 in my case. I downloaded this to an SD card, turned the Pi off, put the SD card in the Nextion's slot, powered the Pi and the Nextion told me the file was too old. Oh good. And all the others I found on the web failed the same way.

So the next step was to use the Nextion editor to convert the relevant HMI file to a new tft. This is Windows only software. Will it run under Wine? No!

I do not have a Windows PC. The wife's work laptop is locked down so one cannot install software - fair enough it is theirs. We had an old Windows PC that had not been powered for maybe two years so that was cobbled back together and turned on. After an age of it configuring itself and updating etc. I finally got the Nextion editor installed, loaded the HMI file, compiled it and put the resultant tft onto the SD card, repeated the Pi off, card in, Pi on sequence and it successfully loaded onto the Nextion. Rebooting revealed it is indeed working.

Now to box it all up... and make sure I never forget all of this again!

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M0RVB

Nextionising the pibox

I gave the pibox a present today in the form of a 3.2" Nextion display. It came with a bezel which I wanted because I could guarantee not to make a neat hole in the panel. Oddly, the bezel was black in the advert but came unfinished... The screen runs off a USB port on the Pi via a CP2102 USB to TTL dongle, and the wires that came with the Nextion just reach the dongle which in on the far side of the box. It was surprisingly easy to set up, albeit I had to wrestle the Windows PC to set up the Nextion editor as I did not have a spare SD card to download the HMI file directly to the Nextion. Of course, this exercise was very much a 'got a new thing, must get it working immediately' type job and I will take time now to read up on it all and maybe find different displays, but it has at least turned a boring blue box into a blue box that appears to have a purpose!

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M0RVB

FT450D, memory tuning and CAT

Interesting event yesterday caught me out. I'd been using the FT450D on 6m FM and had programmed and then selected a memory channel for the local repeater. But when I turned the PC on and ran WSJT-X it gave an error controlling the rig. So I killed WSJT-X and loaded flrig - it too could not control the rig. Then I noticed the rig said M-TUNE (memory tuning). One VFO was still set that way and I presume the program swapped VFOs then lost control and gave the error. I got it out of that and back in to VFO but still no CAT access. Something in the driver (Linux - dunno which driver, probably generic) had got screwed because rebooting the PC cured it all (thinking about it unloading and reloading the driver would probably have worked but by then I'd got into power-cycling mode). This dual VFO business has caught me out before when I had one set to AM and the other SSB. When WSJT-X loaded it switched VFOs but that remained set to AM. Not the programs fault of course but is something to remember. Not a fault of the rig either, just the operator!

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