How to receive more than 20 bytes using BLE GATT custom profile?

[Rajendra]

Hello there,

I am using nRF52840 PDK and nRF5_SDK_for_Thread_and_Zigbee_v1.0.0 SDK for BLE and Thread development. I also have a BLE smartphone app communicating with nRF52840. Using BLE GATT custom profile I am able to receive 20 bytes at nRF. I need to transfer more bytes(approx 128 bytes) from smartphone app to nRF. One way is to send multiple chunks of 20 bytes but it would require multiple packet exchanges.

I have found some references on this forum but these are old, some being older than 6 years. I could not come to any conclusion. Is there any way I can achieve this?

Regards,
-Rajendra

[Vidar Berg]

Hello,

Is this for a BLE-only application? I would recommend you upgrade to nRF5 SDK v17.0.2 (or nRF5 SDK for Thread and Zigbee v4.1.0 if you use Zigbee or thread), and also get hold of nRF52840 DK for development. The 52840 IC on the preview kit (PDK) is an engineering sample and thus not recommended for development.

You can use the UART/Serial Port Emulation over BLE as a reference on how you can increase the increase the payload from 20 bytes to 244 bytes. It uses the GATT Module to negotiate longer MTUs with the connected client.

Regards,

Vidar

[Rajendra]

Thank you Vidar!

Good to hear that large no of bytes are supported with latest sdk. I am upgrading from nrf pdk to nrf sdk, hw v1.0. I will be using  nRF5 SDK for Thread and Zigbee v4.1.0. My application uses ble+thread+uart. I am writing data received over BLE to uart and vice versa.

Regards,

Rajendra

[Vidar Berg]

Hi Rajendra,

No problem! Just let me know if you have further questions to this. It sounds like the BLE UART and Thread MTD CoAP Client Examples may be a good starting point for you.

Regards,

Vidar