in \connect SDK\v1.5.0\nrf\samples\bluetooth\peripheral_uart,data number is limited 20 bytes, more than 20bytes BLE will part data in two or more packs to send or receive

[zhouhaifang]

in \connect SDK\v1.5.0\nrf\samples\bluetooth\peripheral_uart,data number is limited 20 bytes, more than 20bytes BLE will part data in two or more packs to send or receive .how can i chang to data number to more bytes. for example , i want to send 200 bytes through COM  in one time and BLE receive 200bytes i one time , relatively HOW to send 200bytes data in one time  through BLE ,not separate 200bytes data in many pack to send

[Einar Thorsrud]

Hi,

20 byte is the maximum payload you get per packet without using DLE (GAP payload is 23 byte, and 3 byte GATT header leaving 20 byte data). To send longer packets you need to use data length extension. To support that you need to set CONFIG_BT_USER_DATA_LEN_UPDATE=y in your prj.conf and use bt_conn_le_data_len_update() to initiate the DLE procedure. You can see an example of this sin the Bluetooth: Throughput sample.

[zhouhaifang]

thank Einar Thorsrud ,in example throughput  need "

Testing

After programming the sample to both kits, test it by performing the following steps:

",now i have only one nrf5340dk board ,the test is a bluetooth APP in a phone with nrf5340dk , i cannot flash APP ,the APP GAP payload is more than 200 BYTES ,how can i send more than 20 bytes in a bluetooth packet to APP in example peripheral_uart

[Einar Thorsrud]

The example is intended for two DKs yes, but you can refer to the example to see how you can support data length update (DLE). You can see relevant configurations in the prj.conf. Specifically you should add:

CONFIG_BT_USER_DATA_LEN_UPDATE=y
CONFIG_BT_CTLR_TX_BUFFER_SIZE=251
CONFIG_BT_CTLR_DATA_LENGTH_MAX=251

If you want to start the DLE procedure from the nRF you call bt_conn_le_data_len_update().