Unofficial Nextion/TJC User Forum

Upload FW via serial - never reaches 100%


I have a project, where I want to upload a Nextion Firmware from an ESP32, where the TFT file is stored on the ESP in SPIFFS file system. Yes I have found the ESPNexUpload library, but it looks way-way overkill. It is also full of string operations, what is considered as a big no-no in microcontrollers’ world. I checked the documentation of Nextion Upload Protocol V1.1, and it looks pretty easy and straightforward, so I implemented it… Aaaand it does not work. :frowning:

The issue is, it sends the whole file, but the display says only about 90% of the packets has arrived. When I put a delay(100) (or 200 or 300 or 500) between each packet, then it goes up to 99% of all bytes, but it still waits for more. (It changes, but 6-8Kbytes are missing, so not only the last partial package.) When I put delay(1000) between each 4096 byte packages, then it works perfectly. (but takes ages to finish) What am I doing wrong? I think I perfectly followed the protocol documentation.
Ohh, and another strange thing: the 0x88 arrives at the end of the while loop from the display, but it still shows the white screen with the small red text, saying “SIZE: 1957708 writing DATA… 90% 1777664” (When I add delay(100), it stops at 99% and 1949696 bytes)

  HardwareSerial SerialNextion(1);
  SerialNextion.begin(115200, SERIAL_8N1, 25, 26);
  File file ="/Nextion35.tft");
    size_t filesize = file.size();
    SerialNextion.printf("whmi-wri %d,115200,0\xFF\xFF\xFF", filesize);

    WaitForNextionResponse(0x05, 10000);

    char buf[4096];
    size_t avail;
    size_t readcount;
    while(filesize > 0){
      avail = file.available();
        readcount = file.readBytes(buf, avail > 4096 ? 4096 : avail);
        SerialNextion.write(buf, readcount);
        filesize -= readcount;
        // delay(1000); would solve the problem here
        WaitForNextionResponse(0x05, 10000);

    WaitForNextionResponse(0x88, 10000);

void WaitForNextionResponse(byte ResposeToWait, uint32_t TimeoutMillis){
  byte b = 0;
  uint32_t waittime = millis();
  while(b != ResposeToWait && (waittime + TimeoutMillis) < millis()){
      b =;
      waittime = millis();

Got it! The issue is (as always): The controller did the thing I told it to do, and not what I wanted to do. :man_facepalming:

In WaitForNextionResponse
while(b != ResposeToWait && (waittime + TimeoutMillis) < millis()){
The while should run when waittime plus TimeoutMillis is LARGER than millis(). Not smaller. :face_with_symbols_over_mouth:

So it always returned isntantly, without waiting the response from Nextion.


Man if I had a nickel for every time I made that exact same error I would… well I would be making nickels in a very weird manner but you get the idea.

Glad you got it sorted and thanks for the follow up!

Just curious…
Could I use this to upload files (not a project file) to the nextion SD?

I’d like the esp32 to be able to upload media like audio to the nextion for playing via the nextion audio control…

Uploading files (other than .tft files) to the RAM or the SD card is only supported on the intelligent P series. It can’t be done in the same way as firmware updates, the twfile command has to be used.

Thanks Fjodor…

I’m very new to this and trying to decide if Nextion is the way to go for my project.
If I can hand off the playing of audio files to the Nextion (instead of esp32) then it might be attractive…

Is there any way to dynamically (via serial) to get files to/from the SD cards on the enhanced models?

No, the Enhanced models can use the SD Card only and exclusively for firmware updates (.tft files).
The Intelligent models can definitively do a lot more with the SD card.

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