Fastest peripheral to central small packet transfer (nRF52)

[Colt]

I am trying to send small data packets of up to 9 bytes at the fastest and most consistent rate from a nRF52 peripheral to a nRF52 Central. Both use the s332 SoftDevices.

What seems to give the best results is:

1. MIN and MAX CONN INTERVAL SET to 7.5ms in both Central and Peripheral
2. Calling ble_nus_string_send at a 10ms rate

The above yields transmission packets sent generally less than 25ms apart but sometimes they are > 50ms apart.

I tried waiting for a BLE_EVT_TX_COMPLETE event and then immiedely calling ble_nus_tring_send again the peripheral but when I did the rate was much worse than the above.

Does anyone know the best setup to achieve the fastest and most consistent packet transfer of up to 9 bytes?

[run_ar]

Could you be using indications? Try to use notifications instead, it should be possible to send multiple packets in each connection event also at 7.5 ms events.