Nextron Display and smeter wiring

Bruce Morrell

Bitx community,
I very successfully installed the 3.2 inch Nextron Display along with the KD8CEC firmware.  Ian is a genius.  I discovered a discrepancy when I went to build the Smeter and swr bridge.  I used the following diagram as shown in the document UBITX V6 2.8” NEXTION TFT DISPLAY MODIFICATION.  The diagram shows the red wire, +5 going to pin 1 and the black gnd going to pin 2.  All other documentation I have for the connector p2 say pin 1 is gnd and pin 2 is 5v.  Has any one else noticed this and can I assume two things, the document is wrong and the Nextron display has polarity protection???  On a second note does it mater which radinuo the smeterr is connected too??  Ian shows it going to the Ubitx radinuo and the smeter going ancillary radinuo.   Both Radinuos are running the same firmware, so Ian offloaded the realtime smeter display to the secondary.  It makes sence he would also offload the power meter.  Is this also a mistake??
Thanks for your help on this matter KB8MW Bruce



Bruce Morrell

Ok Let me clarify.  I was asking if the Nextion display has polarity protection??  Or have people been making this modification and catching this error???

I was talking about the power meter not s meter.  Does anyone know if the there is an error on KD8CEC documentation which shows it going to the primary raduino and not the secondary nanoarduino??? or am I the first to try this??

Gary Anderson

V6 "TFT" Raduino board is different than the older plain Raduino board.  I think this is the source of  1/2 your confusion.

2 +5V

1 +5V

Can't answer the other parts of your question without spending some time reading.  But it makes no sense that 2 Nanos would be running the same firmware to do different tasks.
1 Nano running the Raduino and the other Nano running  auxillary tasks with a communication link between the 2.


Bruce Morrell

Thank you for that clarification.  It is mind boggling to keep track of v5 vs v6 changes and which documentation you are looking at.   

KD8CEC documentation requires that you read several blog posts to stitch together his projects.  My conclusion was the same software is used in both arduinos with the realtime function offloaded to the second.  If anyone has clarifcation on that please speak up... Bruce 

Evan Hand


Here is the link to the material that references the second Nano.

In that post, he does provide the link to the software for the second Nano.  Also, note that the first Nano has to run different software as well.  For the main Nano (the one mounted on the Raduino board) here is the GitHub link:

Note that the correct version for the v6 is the v5 files.  Also, note that the correct version for a two Nano system ends in _S.  There is a text file in the zip files that give the which file to us information.

We who use his software owe a lot to KD8CEC for all the work he has put into this fantastic system.  I would agree that it is really difficult to follow and find all of the information on his blog.  I have been doing so for 2 years now and still have problems remembering and finding the correct information.

Hope the above information helps you find what you want/need.