How to incease MTU size form 23 to 50 in nrf52810 with S112 ?

[ZL_Chiu]

Hi.

code base is sdk 17.1.0

MCU : nrf52810

Softdevice : S112 (7.2.0)

use SES 5.42a

step1. modify NRF_SDH_BLE_GATT_MAX_MTU_SIZE form 23 to 50 in sdk_config.h

step2. modify RAM_START=0x20001a40 to 0x20001ad0

step. Rebuild and ru with PCA10040

step4. Connecd with nRF connect for desktop bluetooth low energy

step5. Write data ( The data length is 25)

result: Error occur form nRF connect for desktop bluetooth low energy (Write operation failed : Invalid length 0x010D)

[Vidar Berg]

Hi,

It should be sufficient to increase the NRF_SDH_BLE_GATT_MAX_MTU_SIZE value as you did as long as you are using the GATT module to handle the MTU negotation for you. Do you have any debug logs from the device that shows the result of the MTU negotiation? The error message " (Write operation failed : Invalid length 0x010D)" is also a bit strange. I don't see how the length could have become set to 0x10d = 269 bytes. Are you able to write 47 bytes (50 - 3 byte ATT header) if you use the nRF Connect app on Android or iOS? 

Best regards,

Vidar