What does the "add value" function in nRF Connect do?

RE: What does the "add value" function in nRF Connect do?

Kenneth — Thu, 25 Jun 2020 08:26:50 GMT

I am not familiar with the ios/android api, but if the characteristic on the peripheral is configured with a max length of 20bytes, then you would need to perform multiple writes to transfer more than 20bytes yes.

Kenneth

RE: What does the "add value" function in nRF Connect do?

William Geng — Wed, 24 Jun 2020 18:17:41 GMT

Sorry for the confusion I chose the wrong tag :( I am referring to the nRF Connect mobile app in this case. The max length field of the characteristic on the nRF52832 is 20 bytes, does that mean I would use the add value function to chain 13 byte arrays writes to complete the full transmission?

RE: What does the "add value" function in nRF Connect do?

Kenneth — Wed, 24 Jun 2020 11:37:55 GMT

Hello,

I think I need some help to understand the context. Is this "add value" in nRF Connect mobile app or in nRF5 SDK? From a high level typically data will be fragmented by some layer in BLE. In general you may find this useful:
https://punchthrough.com/maximizing-ble-throughput-part-2-use-larger-att-mtu-2/

If the max length field of the characteristic on the nRF52832 is 20bytes, then you would need to fragment the data in several writes to transfer 248bytes I would assume. If the max length is >=248bytes, then it should be fragmented by lower layers in BLE if actual MTU is 20bytes.

Best regards,
Kenneth