Hi.
I don’t have much experience in writing data continuously via BLE, but I would say that’s probably a limitation of the ESP32 BLE stack.
Regards,
Sara

I am facing an issue on the ESP32-WROOM-32E module related to the Bluetooth BLE write function. When I send continuous data using BLE.write(), the function gets stuck periodically every ~5 seconds for about 2–3 ms. Since my project is time-critical, I need the data to be transmitted continuously without interruption.

I have tried multiple approaches to resolve this issue, including using queues, ring buffers, FreeRTOS tasks, and changing task priorities, but the problem still persists.

Could you please guide me on how to overcome this issue or let me know if this behavior is a known limitation of the ESP32 BLE stack?

Thank you.

Hi.
What was exactly the example that you tested?
Regards,
Sara

after translation I get a lot of error massages, for example:
Arduino\libraries\ESP32_BLE_Arduino\src/BLEAdvertising.h:15,
from Documents\Arduino\libraries\ESP32_BLE_Arduino\src/BLEServer.h:19,
from Documents\Arduino\UART\UART.ino:25:
Arduino\libraries\ESP32_BLE_Arduino\src/FreeRTOS.h:61:35:
error: ‘ringbuf_type_t’ has not been declared
61 | Ringbuffer(size_t length, ringbuf_type_t type = RINGBUF_TYPE_NOSPLIT);

Compilation error: ‘class BLECharacteristic’ has no member named ‘getValue’; did you mean ‘setValue’?

I start the translation without any changes, but I get allways the same messages and the code does not work. I was sure, if I use an example from the IDE it should work, but it doesn’t.
I change the selection to any other boards, but it was the same.
has anyone any good idea why?
best regards
Engelbert

Ok.
pioarduino worked just fine in my setup.

Regards,
Sara

Thanks, Sara!

After installing the pioarduino extension, the error did not disappear. Had to dive deep into the BLE libraries and found the problem. The libraries used by Arduino IDE are different thae the ones used in PlatformIO. Comparing them I found that the offending function BLEScan::start(scanTime, false) was declared differently in the PlatformIO dependencies directory:
C:\Users\ben.platformio\packages\framework-arduinoespressif32\libraries\BLE\src\BLEScan.cpp

Before modification:

BLEScanResults BLEScan::start(uint32_t duration, bool is_continue) {
if(start(duration, nullptr, is_continue)) {
m_semaphoreScanEnd.wait(“start”); // Wait for the semaphore to release.
}
return m_scanResults;
} // start

After modification:

BLEScanResults *BLEScan::start(uint32_t duration, bool is_continue) {
if(start(duration, nullptr, is_continue)) {
m_semaphoreScanEnd.wait(“start”); // Wait for the semaphore to release.
}
return &m_scanResults;
} // start

Of course, the header in BLEScan.h had to be modified as well.

Now it compiles and works ok on the old version of the Espressif 32 platform.

I tried to install the new version, as per your latest tutorial, but run into trouble. After changing the platform line in the platformio.ini file, the system started resolving the esp32dev dependencies, but it seems to have gone into infinite loop somewhere:

Resolving esp32dev dependencies…
Platform Manager: Installing https://github.com/pioarduino/platform-espressif32/releases/download/stable/platform-espressif32.zip
Downloading 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
Unpacking 0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%

Nothing was happening for about 30 minutes, so I terminated the process.
I had to remove the pioarduino extension and reinstall the VS Code…
For now I will stick to the old Espressif32 platform.

Cheers,
Ben

Hi.
That is probably because VS Code + PlatformIO uses a deprecated version (version 2) of the ESP32 core.
To use the latest version, you need to use pioarduino (a fork of PlaformIO that supports the latest ESP32 core version).

We’ll publish a tutorial about that subject tomorrow. So, stay tuned.

Regards,
Sara

Compiling .pio\build\esp32dev\libac6\BLE\BLERemoteService.cpp.o
src/main.cpp: In function ‘void loop()’:
src/main.cpp:36:65: error: cannot convert ‘BLEScanResults’ to ‘BLEScanResults*’ in initialization
BLEScanResults *foundDevices = pBLEScan->start(scanTime, false);

Any ideas?