Data reception over BLE

[chetan98]

Hello NXP team,

I am using KW45 to send data over BLE to KW45 LOC board I have connected multiple device at time 4 to LOC board and sending 170 bytes each from each four device at a time, but when I made log from tera term I observed data loss for all 4 device data received.

can NXP tell how to improve data reception from the the multiple device in LOC board.

FYI I am using LOC board sdk example and LOC board sdk for code development.

Thanks and regards

Chetan

[luis_maravilla]

Hello Chetan,

Could you help us confirm what SDK example are you taking as a base and from which SDK version please?

Could you help us share the log that shows the data loss?

I would recommend checking Bluetooth Low Energy Application Developer’s Guide Chapter 9.10, this indicates a recommendation for multiple connections in BLE. Also Chapter  5.1.2 chapter explains the MTU exchange if you need to send more bytes of data, and this community post talks about working with long attributes. Bluetooth Low Energy - Working with long attributes on a GATT Server - Part 1: ATT_MTU - NXP Communi...

Best Regards

Luis

[chetan98]

Hello,

I am using LOC board SDK and using wireless UART example can you tell me there is any limitation of BLE to send a greater number of packet like for eg. I am sending 240 bytes each at 30ms from 4 device using KW45 evk board and data reception is less and packet or transaction are missed can you tell why it is happening when I am connecting 4 device.

Thanks, and regards

Chetan 

[luis_maravilla]

Please, take a look at the BLE Application Developer's Guide Bluetooth Low Energy Application Developer’s Guide . Chapter 5 Generic Attribute Profile (GATT) Layer, Section 5.1 Client APIs provide some procedures and APIs to configure ATT MTU, discover Services and Characteristics, and initiate data exchanges.  Also, Section 5.1.2 MTU exchange describes the ATT packet, its default size, exchange procedure.

While is it recommended to design small attribute value sizes, GATT layers as Wireless UART can only send 23 bytes of data in a radio packet setting the ATT packet default length to 23, The ATT packet length is set to maintain a logical mapping between radio packets and ATT packets.

I would strongly recommend checking the series[1-4] of community post  Bluetooth Low Energy - Working with long attributes on a GATT Server - Part 1: ATT_MTU - NXP Communi... if you need to send more bytes of data, as explains how to write long attributes involves writing queues, and modifying the ATT_MTU for both GATT client and server to support larger MTU with MTU exchange.

Could you help us confirm if you can test the wireless uart example without increasing the packet size, just modifying the number for multiple connections with the instruction in Chapter 9.10 for both client and server please?