MTU Size Limitation on BLE (BlueNRG-M0+) – Unable to Send Payload >20 Bytes

[DdAz]

Hello,

I am working with the following setup:

• Board: B-L4S5I-IOT-01A
• MCU: STM32L4S5VIT6
• BLE Module: BlueNRG-M0+ (in built in the Kit)

I am currently facing an issue related to the BLE MTU (Maximum Transmission Unit) size. By default, the payload length is limited to 20 bytes, which is insufficient for my application, as my data length exceeds 180 bytes.

I would like to know:

• Is there a way to increase the MTU size on the BlueNRG-M0+?
• Can this be achieved without modifying my existing data transmission mechanism (i.e., without manually fragmenting the data into smaller packets)?

My goal is to transmit larger data packets in a single operation, if supported.

Any guidance or recommended approach would be highly appreciated.

Thank you.

[Imen.D]

Hello @DdAz ,

The BlueNRG-M0 Bluetooth LE stack supports the default ATT_MTU value (23 bytes). Therefore, this value cannot be increased.