IOS Requesting Large Packet

[fgeldenh]

I have an application communicating with IOS Bluetooth and it seems that IOS tries to write characteristics larger than the default. The Trace is shown below. Is this a normal exchange or should I be doing something to prevent this. On Android the flow is normal. I am using custom characteristics of length 20 bytes.

<debug> nrf_ble_gatt: Peer on connection 0x0 requested a data length of 251 bytes.
<debug> nrf_ble_gatt: Updating data length to 27 on connection 0x0.
<debug> nrf_ble_gatt: Data length updated to 27 on connection 0x0.
<debug> nrf_ble_gatt: max_rx_octets: 27
<debug> nrf_ble_gatt: max_tx_octets: 27
<debug> nrf_ble_gatt: max_rx_time: 2120
<debug> nrf_ble_gatt: max_tx_time: 2120
<debug> nrf_ble_gatt: Peer on connection 0x0 requested an ATT MTU of 185 bytes.
<debug> nrf_ble_gatt: Updating ATT MTU to 23 bytes (desired: 23) on connection 0x0.

Thank You

Francois Geldenhuys

[Aleksander Nowakowski]

iOS requests highest mtu and data length automatically. If the device responds with lower values, these are then used by the app. Apps should check CBPeripheral.maximumWriteValueLenght(forWriteType:) developer.apple.com/.../1620312-maximumwritevaluelength