requestAttMtu gets NRF_ERROR_INVALID_PARAM

RE: requestAttMtu gets NRF_ERROR_INVALID_PARAM

dwBreezi — Thu, 21 Feb 2019 15:20:16 GMT

Hmm that seems a little odd to me. Is there another way to make the exchange besides changing the default client_rx_mtu in the adapter the mtu size I want? If not that seemed to do the trick just seems like an odd constraint. Thanks for the info though as I was able to get a lower mtu size since I was trying to mimic and iphone app and they use 185 by default.

Regardless of my confusion thanks for the answer Einar

RE: requestAttMtu gets NRF_ERROR_INVALID_PARAM

Einar Thorsrud — Thu, 21 Feb 2019 13:43:18 GMT

I see. Then that could be the problem. One of the requirements is that the supplied mtu value must be equal to Server RX MTU size given in sd_ble_gatts_exchange_mtu_reply if an ATT_MTU exchange has already been performed in the other direction. You will get a NRF_ERROR_INVALID_PARAM if that is not the case (See SoftDevice API documentation for sd_ble_gattc_exchange_mtu_request() for details).

RE: requestAttMtu gets NRF_ERROR_INVALID_PARAM

dwBreezi — Wed, 20 Feb 2019 16:20:54 GMT

Thanks for taking a look Einar. I passed in 222 as my mtu size I am requesting. It is under the current mtu of 247 negotiated and I wanted to use a unique one for testing purposes.

RE: requestAttMtu gets NRF_ERROR_INVALID_PARAM

Einar Thorsrud — Wed, 20 Feb 2019 16:15:01 GMT

Hi,

The NRF_ERROR_INVALID_PARAM error comes from sd_ble_gattc_exchange_mtu_request(), and is typically because you have supplied an invalid MTU size.