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Display Hookup
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vidarr:
I have a 3.5 Nextion display that has some empty pads. One of them looks like it could be for a micro-usb (was included loose with the display new). I look at the circuit and it looks like it very well could be. Can someone else please take a look. I am new at this, so surely there are much smarter folks than me around.

Attached is the back of the display. The J4 pads are at the bottom. Notice the circuit goes by the battery location, thru some switches, capacitors, resistors, timer? Maybe for charging the battery? Then some lines look maybe go to the processor chip? If a better pic is needed, let me know.

Thank you!

Vidarr
janoc:
That cannot be a micro USB. Micro USB connector has 5 small signal pads (+D, -D, Vbus, GND and ID signals) and 4 (or more) mechanical pads around it.

Like this (look from the bottom):
https://media.rs-online.com/t_large/F0435706-01.jpg


That J4 footprint looks like some sort of power connector - notice that one pin is on the top copper pour, likely ground, and the other one goes to the D6 diode (below the U7 chip), most likely a reverse polarity protection. And the circuitry is certainly not a charger, the button cells are not rechargeable (in fact, they will likely explode/burst if you try to charge them!). The battery holder is there as a backup for the real time clock in the STM32F103 microcontroller in the center.

But why are you speculating about what the connectors are for like this? They are certainly documented in the Nextion documentation, no? These smart LCDs generally use a normal serial port (UART) to communicate.

See here:
https://nextion.itead.cc/resources/datasheets/

And this is maybe what the micro USB connector that you have found included in the box was meant for:
https://nextion.itead.cc/wp-content/uploads/2017/09/Nextion_Power_Supply_Test_Board_05.png

I.e. to connect the display to a phone charger as a 5V power supply in order to test it.
vidarr:
OK, so it is some kind of power and not any usb. Thanks.

I already used the included usb for power like it said in the docs to quickly test it. But, I have a breadboard with another power source so it is not really needed.

Yes, they sell uart adapters like this:

https://www.amazon.com/RobotDyn-Serial-Converter-adapter-CH340G/dp/B072637KDK

I was hoping to send data to and from the device without using an adapter (I live in Brazil and shipping takes almost 6-8 months). Right now, I have  to use a microsd card back and forth to the computer, which is ridiculous.


There is also, on the side, some pads for some on-board programming I think?


Maybe do something *kind of like* this:


http://fab.cba.mit.edu/content/archive/projects/fabisp/

Thanks,

Vidarr


edit: I don't know if I make sense. Translate the technical is hard so I try to make it short, but it seems not right. When I read what I wrote above, it is not exactly what I want to say.

Maybe I say to make sense:

Need to read/write to display without transferring data with microsd card, or buying a uart/usb adapter. Is there some connections I can make to the circuit board to do this? There was no documentation coming with the display. Nothing on Nextion site to explain this. Contacted Nextion - they said closed and will not discuss.

vidarr:
Can someone please help me? I think I started this post wrong I got too stuck on the J4 question when it really wasn't my question.

I need help to do this. If I wrote wrong in English I try to explain better. I just need help.

Thank you.
bob225:
Have you downloaded there editor ? https://nextion.itead.cc/resources/download/nextion-editor/ you connect to the display with a usb - ttl adapter or you can program it via sd card - you may be able to program it via arduino


TBH im not familiar with these displays as I use 4d system displays with there own ide
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