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BLUENRG-MS characteristic update truncated at 20 bytes

Question asked by Asela Leelaratne on Feb 12, 2018
Latest reply on Feb 13, 2018 by Asela Leelaratne


I'm using BLUENRG-MS (SPBTLE-RF) module for a low power BLE application. I'm having issues with pushing updates from the module to a mobile device.



The BLE H/W is acting as a peripheral device and a mobile is acting as a central device.

Characteristic size is 93 bytes.

When a read is triggered from the mobile device, full 93 bytes is received.

If I subscribe for change notifications from the mobile device, and update the characteristic data on the peripheral, only the first 20 bytes are received at the mobile device.


Why is the update limited to 20 bytes ?

Is there a way to increase the update buffer size ?


I've been searching the internet and looking at STM documentation but couldn't find a reasonable explanation for this. Not even for the 20 byte limit.

Can you point me towards the correct documentation.


Test H/W:  X-NUCLEO-IDB05A1 on a NUCLEO-L496ZG-P

IDB05A1 F/W: 7.2.c (0x723)

BLE Stack:  BLUENRG V3.0.0 running on L496