Data length extension causes NRF_ERROR_NO_MEM on services init

RE: Data length extension causes NRF_ERROR_NO_MEM on services init

Vidar Berg — Wed, 28 Feb 2018 13:31:33 GMT

the size requirement is static as long as long as you always initialize your services with the same parameters . If not, you should account for the worst case (max. number of characteristics, max attribute length, etc).

RE: Data length extension causes NRF_ERROR_NO_MEM on services init

Eliot Stock — Wed, 28 Feb 2018 12:46:43 GMT

OK, does this get safer if I do it on a later SDK version? Say, 14.1 or 14.2 or even 15.0 once it ships? If my test coverage is not good, am I risking hitting an NRF_ERROR_NO_MEM at runtime in the field?

RE: Data length extension causes NRF_ERROR_NO_MEM on services init

Vidar Berg — Wed, 28 Feb 2018 12:27:32 GMT

Unfortunately, there is no easy way to calculate the required size (the internal table structure is not documented). We actually recommend to determine the required size by trial and error. I.e., increase the ATT table size until you no longer get the NRF_ERROR_NO_MEM error. Note that the size must be a multiple of 4.

RE: Data length extension causes NRF_ERROR_NO_MEM on services init

Eliot Stock — Tue, 27 Feb 2018 18:52:31 GMT

OK thanks, but what do I set it to? How do I calculate the required size?

RE: Data length extension causes NRF_ERROR_NO_MEM on services init

Vidar Berg — Tue, 27 Feb 2018 18:47:05 GMT

Hi Eliot,

The maximum MTU size will typically define the max. attribute data length for a BLE characteristic. Thus, a longer MTU may actually increase the size of the ATT table that is stored in SD memory. You can increase the ATT table size by changing the NRF_SDH_BLE_GATTS_ATTR_TAB_SIZE define in sdk_config.