Sending more than 20 bytes in write characteristics

[Newbie]

HI,

I am using sdk 12.2.2 and nrf52. I have write characteristics in my beacon but I can only send 20 bytes in one write cycle. How can I send more than 20 bytes?

[Simon]

There are several ways of sending more data through advertising:

• Add scan response data: An additional set of 31 bytes can be sent as scan response after a scan request is received. This can be achieved by sending the scan response data as an argument to the function  ble_advertising_init(..). Read more about how to implement it here.
• Increase the MTU size: Increased payload can be achieved by sending it over several packets. The ATT_MTU Throughput Example demonstrates how this can be implemented
• Use extended advertising: If your chip supports BLE 5, more data can be advertised by offloading it to secondary channels. Download SDK 15.2, and use the RSCS example as a template on how to implement it.

Best regards,

Simon

[Nguyen Hoan Hoang]

No, you cannot. That is the limitation of BLE 4.  You'll need to breakdown your transmission to multiple send of 20 bytes.  With BLE5 you can send bigger packet.