ble_gap_data_length_params_t range

[Youssif]

Hi

We are trying to port our app from softdevice v3.0.0 to softdevice v5.0.0. We note that the data length and bandwidth configuration procedure has changed drastically, including the introduction of the sd_ble_gap_data_length_update() function. My question is regarding the tx/rx time parameters of the function: what is the valid range for these parameters? Is this related to the packet length used? if so, what is the dependency?

I've tried following the migration document pseudo code, but the tx/rx time used there is BLE_GAP_DATA_LENGTH_AUTO. Is there any other source/description that we can follow?

We are using nrf52832, with softdevice S132 v5.0.0.

Thanks

[Petter Myhre]

Does this answer your question?

The max tx/rx time depends on how you have configured the SoftDevice. It is related to connection event length.

[Youssif]

Thanks for your quick answer. Unfortunately this does not answer my question as there is no mention at all about ble_gap_data_length_params_t nor the range of tx/rx time. You say that the tx/rx depends on the configuration, but what exactly is the dependency? Which part of the softdevice is it related to and is there a formula or equation etc? Is there a detailed description/material that I can read on this?

[Petter Myhre]

I was a bit quick on the trigger regarding the max tx/rx time, sorry. Actually, you should just disregard them. They are not implemented. The only allowed value is BLE_GAP_DATA_LENGTH_AUTO, which is 0. You should only set the number of tx and rx octets, and they should be equal.

I will try to explain the relationship between the usage of sd_ble_gap_data_length_update() and the event length, but I will need to get clarification on a few things first. Will probably give you an update here on Monday.

[Petter Myhre]

I have looked a bit more into it. So as I mentioned max_rx_time_us and max_tx_time_us should be set to BLE_GAP_DATA_LENGTH_AUTO. max_rx_octets and max_tx_octets should be equal, and valid values are 27-251. If sd_ble_gap_data_length_update() returns 0x13 -> NRF_ERROR_RESOURCES, the limitation should be examined. If tx_rx_time_limited_us is 0, then you need to increase the max ATT MTU set when enabling the SoftDevice. If tx_rx_time_limited_us is not 0, then the event length should be increased with the specified number of us.

[safwath]

@petter myhre any update on that so far?