How many Kbytes per second we can reach in ble_app_uart?

[Zhang Yubiao]

F:\nRF5_SDK_16.0.0_98a08e2\examples\ble_peripheral\ble_app_uart

I tested above example, found the speed only 3K per second. Do we have a way to increase the speed?

[Håkon]

Hi,
Have you looked at this guide?
https://devzone.nordicsemi.com/nordic/nordic-blog/b/blog/posts/throughput-and-long-range-demo 

[Zhang Yubiao]

• Connection interval: The connection interval defines how often the devices must listen on the radio. When increasing this value, more packets can be sent in one interval, but if a packet is lost, the wait until the retransmission is longer.
• Data length extension (DLE): The default data length for a radio packet is 27 bytes. Data length extension allows to use bigger radio packets, so that more data can be sent in one packet.

Where to set the above parameters in ble_app_uart?

[Håkon]

Hi,

In main.c
Connection interval:
Line 94 and 95 defines the connection interval min/max

DLE:
Line 114 defines the packet size.
BLE_GATT_ATT_MTU_DEFAULT is 23 bytes, but can be changed to NRF_SDH_BLE_GATT_MAX_MTU_SIZE -3 instead. 
This I have not verified, but I will ask my colleagues if this is the correct approach.
However, feel free to test your self in the meantime. 

static uint16_t   m_ble_nus_max_data_len = BLE_GATT_ATT_MTU_DEFAULT - 3;           
/**< Maximum length of data (in bytes) that can be transmitted to the peer by the Nordic UART service module. */

[Zhang Yubiao]

#define MIN_CONN_INTERVAL MSEC_TO_UNITS(20, UNIT_1_25_MS) 
#define MAX_CONN_INTERVAL MSEC_TO_UNITS(20, UNIT_1_25_MS)

Is there a range for MIN_CONN_INTERVAL change? 

[Håkon]

This post discusses some connection parameters: https://devzone.nordicsemi.com/f/nordic-q-a/28058/what-is-connection-parameters

Connection interval must be in range 7.5 - 4000 ms.