[Qeustion] data send delay error

[seungwooWoo]

HI, I am seungwoo

I am developing data transmission using nrf52810.

A 300-kilobyte file is divided into 220 bytes and transmitted continuously.

11-27 17:24:24.416 W 15138 lbs_tag_service woo send4 packetInteration = 212total = 1543
11-27 17:24:24.418 E 2945 bt_att gatt_act_write() failed op_code=0x52 rt=143
11-27 17:24:26.236 W 15138 lbs_tag_service woo send4 packetInteration = 213total = 1543

If I send data, periodically, the above bt_att gatt_act_write () failed op_code = 0x52 rt = 143 occurs.

This error delays a lot of time.

GATT_CONNECTION_CONGESTED

added in API level 21

public static final int GATT_CONNECTION_CONGESTED

A remote device connection is congested.

Constant Value: 143 (0x0000008f)

The issue is thought to occur when the android ble stack becomes full.

I think I can not get the best speed if I get a delay of about 2 seconds every time the stack is full.

I want to know if there is a workaround.

I am using example ble_app_uart.

[seungwooWoo]

HI, Aleksander Nowakowski 

I will contact you with further inquiries.

I tested with another device.

SAME = MTU 256 , packet 1534

1. Nexus5(central) -> Nexus5(BleUARTPeripheral) 

  - https://github.com/thejeshgn/BleUARTPeripheral/tree/v1.0(source code)

12-05 15:47:15.609 W 8770 lbs_tag_service woo onCharacteristicWrite = 340total = 1543 status = 0
12-05 15:47:15.610 E 2940 bt_att gatt_act_write() failed op_code=0x52 rt=143
12-05 15:47:16.252 W 8770 lbs_tag_service woo onCharacteristicWrite = 341total = 1543 status = 0

The same congested error occurs.
But it only takes 0.7 seconds to send the next pack.

2. Nexus5(central) -> nrf52810(ble_app_uart)

11-27 17:24:24.416 W 15138 lbs_tag_service woo send4 packetInteration = 212total = 1543
11-27 17:24:24.418 E 2945 bt_att gatt_act_write() failed op_code=0x52 rt=143
11-27 17:24:26.236 W 15138 lbs_tag_service woo send4 packetInteration = 213total = 1543

The same congested error occurs.

But it only takes 2 seconds to send the next pack.

Can you tell why this difference appears?

Thanks you