I’m working on a project where the ESP32-S3 receives an ESP-NOW message from a sensor node and updates the UI using LVGL. Everything works well until I trigger a command to send a “Fan OFF” ESP-NOW message back to the sensor.
After this send, my screen glitches, as if the draw buffers are corrupted or invalid. Areas of the LVGL UI becomes unreadable, and I have to reset the board to clear.
Here are a few specifics on the two esp boards.
LCD: WT32-SC01 Plus (ESP32-S3)
Sensor Node: ESP-WROOM-32 ESP32 ESP-32S Dev Board
Graphics: LVGL 8.3.11 + LovyanGFX
Framework: Arduino via PlatformIO
PSRAM: Enabled
I’ve confirmed:
- The glitch only happens after calling
esp_now_send() - Using
lv_disp_get_inactive_time()to delay the send doesn’t help consistently - LVGL is rendering correctly otherwise (boot logo, pills, layout, etc.)
- I am not modifying LVGL from any other thread or interrupt
What I’ve Tried:
- Deferring the ESP-NOW send until
lv_disp_get_inactive_time()is > 50ms - Disabling LVGL rendering just before the send (by halting
updateLVGL()) - Replacing deferred timer logic with a simple flag in
loop() - Reducing SPI speed
- Using a separate LVGL task (no improvement)
Right now my only option for fan control is to eliminate the “Fan OFF” all together. The fan PWM control is through a MOSFET, which does allow for the fan to maintain a complete OFF status without the use of a relay, but I’m running into this glitch. I’ve attached a photo for reference as well. I’m not really sure which parts of the code to share, as its quite extensive.
