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Brick 7" Nextion Screen

Hi,


Screen was working well. After, was a problem with the power circuit on Arduino.


Now, secreen is working (touch panel, light, and everything) but uart not working.


It certainly does not do communications.


I wonder why?


Thanks...

https://s22.postimg.org/sleyele5t/14114626_10208318889868566_1121305974_o.jpg




Is there any other method of communication? These pins What does?




Try compiling a blank project in the Nextion Editor, open build folder, copy the blank tft file to an empty fat32 formatted microSD card.  Power the screen to off, insert the microSD card, power it back on.


Does this fix your issue?

Hi Patrick,

Upload blank image with sd card, after on off, after upload my image. But not work uart communication. 


Note: Same this image, working wtih other 7" nextion screen.  This screen not work.

If I am not mistaken, the RX/TX lines where you clip in go straight to the STF32F0 USART RX/TX (I don't have a 7.0" Display).  If the rest of the Nextion is working, you haven't blown the STM32F0 chip or at least not all of it (I would assume it would all go, not just some).


Have you ruled out :

  • connecting wires are good
  • voltage is now proper, common ground, etc
  • that the replacement MCU is not the cause of communications not working



The pin pads you outlined would be for initial factory programming of the chips and QC

The left one for the STM32F030, the other I believe is for the Altera MaxII


Neither of these would provide anything suitable communications for an MCU

If I am reading your answers, you have two 7.0" displays?

One is the uart not working

the other is  Known Good


You project works with the Known Good display, but not with the first?

Yes, i have two 7" same screen. 


Fisrt screen not working communications. Second screen good working communications. with same project and same circuit and everything same.


Fisrt screen was working well. After, was a problem with the power circuit on Arduino. It's working (touch panel, light, and everything) but uart not working.

Last thought:


Open a Service Ticket - see if Itead has a repair service for this


If not, and you want spend the time to experiment (and only if Itead can not repair it)

- there is a second UART on the STM32F030 at pins 12 (TX) and 13 (RX)

- these pins are free and unused on the smaller models (I imagine free on the larger models)

- these pins 12 and 13 ARE NOT 5V Tolerant, they are 3.3V (need a level shifter)

- you would need to run a bypass from the connector through the level shifter to Pins 12 and 13.

- you would need to work out a way to try and patch the TFT file to switch the address and configurations from the original pins 30 (TX) and Pin 31 (RX)

- would only work if the internal STM32F030 circuits don't lead back to the same register/buffer hardware.


That is the only other communication option that I can think of.  The hassle required to pass the uart communications through the serial wire debug port (the pin pads) would require that you put the stm32 into a debug mode where you could change registers during runtime (catch the comm request, pause, alter as needed, resume) - unless someone knew of something easier.

So I am back to my original:

Open a Service Ticket, I would think Itead would be able to repair it even if it was repaired for a fee.

pdf

Thanks Patrick, i hope, problem is dissolved. Because its expencive.

Last post on the ticket. :/







They are what for? How will this problem be solved?




1) #1 IS pin pad for Serial Wire Debug for the STM32 MCU located just to the right of your "1"

2) I am assuming is the pad for the Altera MaxII to program it.

3) Unsure.

Hi Patrick, I did not understand it. where these pins?



If not, and you want spend the time to experiment (and only if Itead can not repair it)

- there is a second UART on the STM32F030 at pins 12 (TX) and 13 (RX)

- these pins are free and unused on the smaller models (I imagine free on the larger models)

- these pins 12 and 13 ARE NOT 5V Tolerant, they are 3.3V (need a level shifter)

- you would need to run a bypass from the connector through the level shifter to Pins 12 and 13.

- you would need to work out a way to try and patch the TFT file to switch the address and configurations from the original pins 30 (TX) and Pin 31 (RX)

- would only work if the internal STM32F030 circuits don't lead back to the same register/buffer hardware.


That is the only other communication option that I can think of.  The hassle required to pass the uart communications through the serial wire debug port (the pin pads) would require that you put the stm32 into a debug mode where you could change registers during runtime (catch the comm request, pause, alter as needed, resume) - unless someone knew of something easier.

There is a lot to read to get a full understanding.  The chip to the right of #1 is the MCU.
The diagram was on the bottom of Page 25 on the pdf I uploaded above.



To identify the pins, you would have to orient the chip so that the small dot in one of the corners would line up with the diagram in the products spec sheet I attached.  That portion will only identify the two available pins for USART on the STM32 MCU.


What I don't have figured out yet is how to patch the firmware.  That is going to take a lot more reading and debugging the code to nail down.  The ST website has the programming and reference manuals for the chip -- but don't kid yourself - it is quite a bit of work to pull it off.  It is even more work to ensure that your patch is only changing exactly what you need without breaking the firmware.  It can be done because with an ST-Link V2 and the pad identified in by #1 gives access to the STM32 chip.


You have a lot of reading to do before you get to where you are ready to patch.  Programming manual is 91 pages, the Reference Manual is 771 pages.

pdf
(10.9 MB)
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