Evan Suits asked 2 months ago
I just ran into a non-functioning display problem with my latest order of ESP32 CYD modules. The modules came from AliExpress and are described as “DIYUSER ESP32 LVGL WIFI&Bluetooth Development Board 2.4 inch Touch LCD TFT Module 240*320 Smart Display Screen With Touch WROOM”. Full product URL appended below.
When I compile and upload the recently published “ESP32 CYD with LVGL: Digital Clock with Time and Date” guide, the Serial Monitor shows the code is working, including the WiFi connection, but the display remains dark. The same exact code works fine on four other CYD’s purchased from Amazon and AliExpress.
The displays on the two new CYD’s worked fine on initial power-up, demonstrating a very impressive, highly detailed, extremely colorful tabbed display with touch sensitivity. There was no obvious problem with the Digital Clock upload, except the display remaining dark.
These new modules differ physically from the ones previously obtained from Amazon and AliExpress. The most obvious differences are the USB-C host connector and the RGB LED located located on the display side of the module. I found them listed among many other CYD variants on the AliExpress website and ordered a pair based on their cost, about half what Amazon charges. I’m not out much money but I’m disappointed and I’d like to know whether it’s possible to determine from the ‘catalog description’ which CYD modules will work properly with the “Learn LVGL” course code.
Or, is there an LVGL tweak needed to activate certain CYD displays? The recent LVGL update to 9,.2 was surprisingly noisy and the changes to the RNT supplied include files suggest that LVGL as a whole is a moving target.
Thanks in advance for any help.
– Evan
Product URL: https://www.aliexpress.us/item/3256807166175851.html?spm=a2g0o.order_detail.order_detail_item.4.4a76f19cxnD6yh&gatewayAdapt=glo2usa
Sara Santos Staff answered 2 months ago
Hi.
Your board probably has the colors inverted.
Check page 92 of the eBook with some suggestions to fix that issue.
Also, check these discussions:
- https://rntlab.com/question/colors-inverted-on-cyb-esp32-display/
- https://rntlab.com/question/i-bought-the-wrong-cyb-board/
Let me know if any of the suggestions work for you.
Regards,
Sara
Evan Suits answered 2 months ago
It’s not a color inversion but rather no colors whatever. The display simply remains dark as though it has not been enabled. I followed the i-bought-the-wrong-cyb-board discussion and I now see that the TFT_eSPI User_Setup.h has many many driver options as well as other feature bits one can turn on and off. This implies that there are equally many ways of connecting the ESP32 to the display. I may be reduced to trying all of them.
Anyway, thanks for the prompt response.
– Evan
Sara Santos Staff answered 2 months ago
Hi again.
Try to get as much information about your board and then scroll through the User_Setup.h and LVGL config files to see if you can figure out any option that might be suitable for your board.
Many times a black display means that the wiring or pin assignment is probably not correct.
Regards,
Sara
Evan Suits answered 2 months ago
Wilco.
Meanwhile, I ordered a couple more CYD’s from AliExpress, ones that have the micro-B connector and the LED on the component side. Just in case 😉
Evan Suits answered 2 months ago
Looks like this blank display is a pin configuration problem. The USB-C only CYD with the blank display runs Serial “Hello World” tests just fine, so the ESP32 is OK. However, when I build and run the TFT_eSPI example from “Programming the ESP32 CYD (Cheap Yellow Display) with VS Code”, I get a continuous series of bogus ‘touched’ reports via Serial from the loop( ) code. This suggests that the SPI pin assignments are different for this particular CYD, leading to invalid interrupt signals. I’ll have to enumerate and try all the SPI pin assignments.
Along the way I received a third CYD variant from AliExpress which has both micro-B and USB-C connectors. This one has the color inversion problem mentioned earlier, correctable by uncommenting the #define TFT_INVERSION_ON line in User_Setup.h.
Also, this dual USB variant works with either micro-B or USB-C host connection. I’ve seen online complaints that the USB-C on the dual connector variants is not functional. Mine works fine.
Finally, given all the CYD variants available with all the hardware combinations and permutations, I admire the courage you’ve shown by publishing How To’s.
Sara Santos Staff answered 2 months ago
Hi.
Can you please double-check that your displays have the ILI9341 driver like the display we use and recommend.
Otheriwse SPI assignment and the setup files will need different configurations.
Regards,
Sara
Evan Suits answered 2 months ago
I just ran through all the xxx_DRIVER defines in User_Setup.h and none of them brought the affected display to life. I no longer believe this topic is a good use of your time or mine so I propose we abandon the discussion. As long as your readers follow your CYD purchase recommendations, they should be fine.
If there’s a way to disable/archive/freeze or otherwise put this topic to bed, please do so.
And thanks again for your time.
– Evan
Sara Santos Staff answered 2 months ago
Ok.
I’ll close this issue.
Then, if you need further help, you just need to open a new question in our foum.
Regards,
Sara