BLE transfer speed on STM32WB5 and corrupted data

[Kasper-Gjoedesen-Mikkelsen]

I am limited to 150-180 bytes/s on the transfer speed when I write data from the STM32WB55 to a RPI with read and notify.
I have tested different timings for when the device poll and the advertising interval. Furthermore, I have tested with different buffer sizes between 8 and 22, and the data is corrupted if try to send more data than 22 bytes.

Result from a 30 byte uint8_t buffer of zeros: 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01, 0x01.

Is this a config error? and can the speed be increased?

Best regards Kasper G. Mikkelsen

[fpistm]

Hi @Kamik18
Please, could you share you test sketch?

What is your config? Arduino IDE version? Core version? Library version? Selected options?...
all relevant information are welcome to help.

[fpistm]

I guess it have a link to:

STM32duinoBLE/src/utility/STM32Cube_FW/ble_bufsize.h

Line 26 in 23053fb

#define BLE_DEFAULT_ATT_MTU 23

and arduino-libraries#70

[Kasper-Gjoedesen-Mikkelsen]

I am using PlatformIo as my Arduino IDE, and I have tried changing BLE_DEFAULT_ATT_MTU but without any influence on the data.

I tried modifying one of your examples (CallbackLED.ino, examples/Peripheral/CallbackLED/CallbackLED.ino), and kept every variable to their default values, where I used “BLENotify” to write a data buffer in a while loop. I did not use delay or anything else doing that test.
I furthermore tried creating a callback function to send data when requested by a RPI, and again without any delay on either the STM32 or the RPI.

Versions:
PlatformIo Core 5.1.1 and Home 3.3.4
Arduino_Core_STM32 2.0.0
STM32duinoBLE 1.2.0

[KMeldgaard]

I've tried using GrumpyOldPizza's ArduinoCore-stm32wb implementation on the Arduino IDE (following the README guide) and achieved impressive bandwidth. I can transfer ~120 bytes per package - speed is yet to be determined, but it is definitely faster.
However I still have issues migrating the project to PlatformIO.

[fpistm]

Hi @KMeldgaard
Could you test if it works better with latest STM32 Core version (2.4.0), library version (1.2.2) and with an updated Wireless copro binary (HCI layer.bin)

[fpistm]

I've tested and read and write up to 256 and have met no issue with latest core 2.4.0, latest library version 1.2.2 and latest wireless copro binary.