LVGL and BLE on ESP32

[lixas]

Hello

I have an issue, that i can not use BLE in my LVGL micropython application. As and example i took advanced demo application as my starting point, for slightly modified ILI9341 and XPT2046. Built an UI that i like, and then i tried to implement BLE scanning functionality. And i failed at this point...

I was able to narrow down my issue to bare minimum:

import ubluetooth
import lvesp32          # <-- This breaks BLE scanner irq

def bt_irq(event, data):
    print(event, data)

ble = ubluetooth.BLE()
ble.active(True)
ble.irq(handler=bt_irq)
ble.gap_scan(0, 30000, 30000)

if lvesp32 is commented out- everything works as expected and i do see BLE advertisement packets. If i import lvesp32 later, when my BLE scanner is running- it stops like in second or so and no more data is shown. Importing lvesp32 is enough to kill/hang/stop BLE scanning process.

What I do need in my final application is read BLE advertisements packets, extract data and show in on LVGL interface on ILI9341 display.

I built firmware on my own computer for generic ESP32 (no external PSRAM)
MicroPython v1.9.4-2805-g46e9073b2 on 2020-09-01; ESP32 module with ESP32

[amirgon]

Hi @lixas !

Please see related threads on forums:

• https://forum.lvgl.io/t/ble-issue-with-xpt2046-py-touch-driver/2604
• https://forum.micropython.org/viewtopic.php?f=18&t=8068

The lvesp32 job is to call lv_tick_inc and lv_task_handler periodically, and it does it by creating a timer (xTimerCreate) and scheduling a task for Micropython.
For some reason this approach does not work well with BLE, I'm not sure why.

Possible workarounds are:

• Change lvesp32 tick parameter to a larger value.
• Avoid lvesp32 completely and instead call periodically lv_tick_inc and lv_task_handler.
• If you are using uasyncio you could use lv_async which replaces lvesp32 and does not require a dedicated timer.

[lixas]

Thanks you for suggestions I'll share outcome of my tests so far:
Parameter =2 works for minimal scenario, bet did not really work for my app. I've finished with parameter =8. So far so good- everything works. But of course, I had to disable animations and transitions- it became choppy...
Also, i understood how to use lv_tick_inc and lv_task_handler functions, so maybe some day later i'll make transition to get rid of lvesp32 and call those functions when needed. Thanks you once again for showing me right way

[stale]

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