Secure buttonless dfu very slow

[gaminn]

Hi,

if my device (nrf52832) is in application and I perform firmware upgrade using nrf connect and PCA10031 on Win 10, the upgrade process is very slow (0.35 kB/s). I stop the process and connect to DfuTarg device (my device that is still in bootloader mode). I select the same app upgrade package and now I get normal speed (1.7 kB/s). I can repeat that, it happens always. Why and how to fix it?

[Vidar Berg]

Hi,

Which SDK version are you using? I suspect it's the connection interval that's different. PCA10031 will also lead to lower throughput if you are testing with SDK 15 since it doesn't support long MTU.

[gaminn]

I use SDK 15.2 . I modified NRF_DFU_BLE_MAX_CONN_INTERVAL in sdk_config.h of the bootloader. I set it to 6 (instead of 40). Now I get full speed where it was 0.35 kB/s previously.

Why nrf connect doesn't select lower connection interval always (NRF_DFU_BLE_MIN_CONN_INTERVAL is set to 6)?

Anyway, I guess this is not big problem for us as normally we will use different host to perform dfu.

[Vidar Berg]

You will likely see higher throughput if you use a nRF52 or nRF connect on android/ios. 

gaminn said:

Why nrf connect doesn't select lower connection interval always (NRF_DFU_BLE_MIN_CONN_INTERVAL is set to 6)?

Probably to reduce power consumption. It doesn't necessarily reduce throughput when DLE/long MTU is supported