A v6 Nextion display conversion

Barbaros WB2CBA  has modified his stock µBITx v6  kit to use the Nextion 2.8″ TFT LCD display.   He reports that it is working well!  

For firmware, he used KD8CEC Ian Lee’s CEC Firmware Version 1.2 for Ubitx V5 found here:

http://www.hamskey.com/2019/04/release-cec-firmware-v1200-for-ubitx.html

As the v6 design is substantially the same as the v5, the software all works fine with settings for the µBITx v5.

The only glitch with assembling the Nextion 2.8″ screen in the standard case supplied with HF Signals kit is a mechanical issue:  the right two spacers/screws can’t be screwed in.  The two left spacers  supplied with the kit are, however, able to hold the display tightly though.   If needs be, additional holes could be drilled to align with the Nextion mounts.

To help his fellow Ubitx V6 owners who want to use a nextion display in their rig, Barbaros has provided a very helpful MS Word guide: 

UBITX V6 NEXTION TFT DISPLAY MODIFICATION.

 

Nextion noise suppression choke

Talmadge Huckabee suggests that  a good source for a Nextion noise reducer choke (2.5mh) is to get a toroid (FT114_43) from kitsandparts.com and wind 70 turns of #22 wire on it.  This has about 1 ohm of resistance so it will not have much voltage drop (and will not dim the brightness of the Nextion display).

Reference

Addressing issues with an SWR meter and the Nextion display

Joel KD6AGW has been working on his UBiTx V5 for a few months now and added the KD8CEC update with Nextion screen and the I2C update.  He had all the features working (CW decode etc) except the SWR meter.

Joel also built a Kits and Parts SWR bridge and hooked it up to the second Arduino.  However, the meter never operated correctly.  The home brew Stockton bridge that Ian (CEC) used apparently did not have this problem.

After hooking up an oscilloscope to the forward and reverse outputs, Joel noticed that the reverse voltage would bounce up to 4 volts or so before settling down after a few seconds.  This was while the uBITx RX input was hooked to a 50 ohm dummy load.  When the probe was hooked up, the meter on the Nextion display would go high, and then settle down to a good swr reading.   However, as soon as he removed the probe to the oscilloscope, the meter would just stay pegged at very high SWR.

He ran across a blog item here (http://www.kk5jy.net/swr-meter-v1/)  about building a digital SWR meter and noted that:

“In order to prevent stray RF from getting into the A/D circuits,  a 0.05uF ceramic disc capacitor was placed between each line and the GND pin.  Since the A/D inputs are very high-impedance, and the SWR sensor outputs were meant to drive current devices (e.g., analog meters), a 75k resistor was placed across each of the 0.05uF caps, to drain the accumulated charge when no RF was applied”.

After doing these modifications, Joel has found the SWR meter to work great.

For information, here is a sketch of the circuit modification:

Following a question about power wastage in the Stockton Bridge SWR circuit Joel checked the output with the bridge in and out.   There was no perceptible difference in power out on the oscilloscope.

Reference

Nextion Bezels for a variety of display sizes

Ian from Computer Freaks Anonymous found the uBITx.net website and let us know about his Nextion bezels.

He has been producing these on his CNC machine for some time now.  They are manufactured from acrylic, have tapped holes to secure the display with plastic screws (supplied).

The bezel allows you to cut a rectangular hole, glue the bezel in place and secure using the screws. It provides a nice glossy finish and they can be produced in many colours. From the front view there are NO screw heads visible, adding a more professional finish to your project.

He ships worldwide, to US, Canada, UK, Austria, Germany, etc.

More info here:

https://www.compfranon.uk/product-category/products/screen-bezels/nextion/

Powering a larger Nextion screen from the raduino

If your larger (4.3″ or greater) Nextion display is flashing, you are probably overloading your Raduino 5v power supply.  This is because the Nextion does draw quite a bit of current.

Mark AJ6CU found a 7805 with a higher rating on Amazon (maybe 1.5A?). He mounted it on a heat sink attached to the rear panel (using the rear panel as a large heat sink) with a small perf board (to mount the appropriate capacitors).  He then brought in a set of 5V wires to replace the 7805 on the one on the Raduino.  This could be a helpful idea for those of you installing Nextion display units.

MVS Sarma suggested using a 78T05 as a replacement to the 7805. This is  a 3amp TO220 device and available very cheaply .   Managing the TO3  is little dìfferent compared to the TO220 on the 7805.
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Nextion noise in RX

MVS Sarma VU3SMV  noticed noise on his receiver generate from his Nextion display.   He placed a 2.2mH RF choke in series to the 5v line feeding the  Nextion display.   He also placed a 220µF capacitor across the 5v and Gnd terminals for the Nextion.  The hash was reduced to just 10% of its original value.

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Lots of development on the 5″ Nextion screens

Mark AJ6CU  has announced that he have completed what he considers a “beta 1″ for the 5″ version of the CEC user interface.

Note this user interface is substantially different than the original one released by KD8CEC (see screenshots below).  It has been optimized for 800×480 screens and is probably not easily migrated to smaller ones (sorry),

But if you are a lucky ham with either a 7″ or 9” Nextion, it should be a simple matter of opening the “.hmi” file up in the Nextion editor, change the Device settings to match your screen, and compile it to create a tft file.  Mark acknowledges the original work done by Joe Puma (KD2NFC).  Without his headstart, Mark says “I would probably have not been able to complete this.”

The files (both .tft and .hmi are in the files section for the IO BITX20 group.: Files/AJ6CU Nextion 5-inch files/Nextion5inch June 23, 2019-Beta1/

The following screenshots show some of the new GUI.

MAIN MENU
The main change here was to Group the various functions in to “Applications”, “Settings” and “Expert”. Mark did some renaming so that it was clearer on the functions. Also, Factory Recovery now has its own screen that clarifies what is happening (for dummies …). And there is an “About” screen…

ABOUT SCREEN
Every applications should have its own About screen. 🙂

Note that in addition to credits and version, there is a list of the three known problems.

Save/Recall from Memory
Mark has added a popup virtual keyboard for adding a label/tag to a memory location. And he has also made sure that the Current VFO setting was kept. That allows you to turn around on your VFO while the Store to Memory is onscreen and you can save it whenever you find something interesting.

BANDSCAN
The Bandscan as originally designed had a number of problems including only able to look at signals 2k at a time and a maximum bandwidth of ~250kHz. This meant that if you scanned 80m, you only got the bottom half of the band. Mark didn’t like the way bands were pre-selected, as he preferred that the user could select any three in any order. He has added several missing bands.  (For folks outside of USA FCC, it is easy to change these bands from within the .HMI file. Let me know if you would like to do this and I will provide details.) . There is still some room for improvements here.  Mark plans to experiment with a smaller frequency step and smaller scan bandwidth. But that would be part of a future effort…

The first photo below shows the popup selection of offsets from the beginning of the band, using a mechanism similar to how the mode CWL/USB, etc is selected on the front page. The second photo shows a completed band scan that gets to the top of the 3 selected bands.

CW Decoder
Mark has made some minor GUI changes and renamed this function to reflect its functionality. He has also added a slider switch on the left to select between Signal analysis and CW decode.

Factory Recovery
Previously, pushing Factory Recovery required  3 presses to run Factory Recovery. But there was no explanation of what it did and why you probably did not want to do it!  Mark has added a separate screen with explanation and double confirmation.

Main Menu
Mark has added direct access to Store/Record to Memory (see upper right). Also he somewhat liked this spectrum that he captured on Field Day. 🙂

Mark’s Setup
Mark has run both a 5″ and a 3.2″ display simultaneously (thanks Ian!) during development. This allowed for quick answers to the inevitable questions such as: “What did Ian originally attend this screen to do?”  It was very helpful and he would recommend this approach to anybody else that is doing development for Nextion screens.

Reference

5″ Nextion screen files

Mark AJ6CU has added an updated version of the KD8CEC Nextion code for the 5″ screens (Basic and Enhanced) to the files sections of GROUP IO BITX20 list. (Only the 5″ Enhanced has been tested, as he doesn’t have a 5″ basic screen to test with.  This work is an extension to the “heavy lifting” already done by Joe Puma (KD2NFC).

Mark couldn’t help himself and did some “improvements” to the user interface that you may or may not like. He has included the HMI file in the directory as well, so you can adapt it how you would like it to look if you know how to edit HMI files.

If you have a 7″ or 9″ screens, you should be able t load up the HMI, set the device to match your screen and regenerate the TFT file. If you have one of these larger screens and can’t figure it out, it is suggested you contact Mark.

Files: AJ6CU Nextion 5-inch files/5inch June 10

A summary of major changes that were made to Joe’s original effort”

  1. Home page
    • Correction of scale for histogram (have more space, so let’s use it!)
    • Addition of direct access to memory STO/LOC screens (had to eliminate the Radio tower logo, sorry)
  2. Various
    • In case you had not noticed, the button to get “Home” was in various locations, although not done, I am in the process of moving it to a consistent place (upper right)
    • Scaling changes to Bandscan and Spectrum
    • Various pages required you to hit “read” or “refresh” to go get the data. I made this happen on page entry. Kept the refresh button as this seems to be a little flakey.
    • Tried to introduce a consistent color scheme. Blue background, white letters where you can change, yellow for titles.
    • All screens (except home screen) will eventually have the name of screen in upper right in red.
    • Button pushes go green when pushed and return to grey when released
    • Added a few more scrollbar slider sizes so that the slider fit the slide bar better.
  3. Frequency entry (touch the middle 3 numbers on home page) is now a little more obvious. When you are in direct frequency entry, you only see numbers, When you are in Band select, you only see the bands.
  4. Memory to VFO redesigned. Seemed easier to use for me.
  5. VFO to Memory – Mark still doesn’t like this one. He would like to make it more like Memory to VFO where you can see all 10 memory slots and then select the one you want to overwrite. For now, he has just replaced the keyboard with a standard one that pops up when you click in the name and some fancy arrows to spin the mem#.
  6. Although it is against his better judgement, he did make available KD8CEC’s debug screen. Tried to warn you off, but i am sure someone will do something awful to his/her poor ubitx using this screen. 😉
  7. CW setup screen redesign (and it automatically fetches data on startup)

There are some issues remaining … The biggest issue being that when you go into a submenu (e.g. CW setup/MemtoVFO, etc.) the Spectrum Histogram in lower left corner doesn’t always automatically restart.

If you change any control VFO/Freq, mode, etc.) it restarts.

This is going to be a pain to debug because of the extensive use of timers and state machine in the Nextion code…. Would welcome anybody that can make a suggestion here.

I have also not tested it on a Basic 5″. There may be performance issues, especially since the scale of the graphs has increased.

Mark says there is still lots of work, as he also wants to get rid of some of thebackground pictures in the control screens that really don’t match the others. The bandscan is something he would really like to “adjust” because it is really not obvious how it works. And perhaps even a “?” in upper right of some screens for a little help?  He plans to  put together another update shortly.

Reference

Bezels for Nextion Screens

Andy, KG5RKP notes that you can retrieve a bezel pattern for any of the Nextion displays from 3.2 through 7 inches from Itead:

https://www.itead.cc/wiki/Nextion_HMI_Solution#3D_printing_bezel

Andy had a bezel printed by a vendor via 3D Hubs:

https://www.3dhubs.com/

David  Balfour has made bezels  for the 2.8 and 3.2″ Nextion screens by 3D prints.   His rig is shown above.

The larger bezel is on thingiverse if you have a 3d printer. https://www.thingiverse.com/thing:3342327

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