Esimate CoAP over BLE power consumption

RE: Esimate CoAP over BLE power consumption

Olivia — Tue, 29 Jan 2019 11:29:40 GMT

Hi Stian,
What is this "End" of 2 Bytes? I thought of the BLE CRCbut I unerstood that would take 3 bytes...

RE: Esimate CoAP over BLE power consumption

marcmar — Wed, 20 Sep 2017 01:14:45 GMT

Thanks for the information. It's like gold for me! , Has the payload a theoretical limit (in bytes)? I'm interested to send more byte trought CoAP over BLE in the range of 1-4 kylobytes. Thank you in advance

RE: Esimate CoAP over BLE power consumption

Stian Røed Hafskjold — Mon, 21 Aug 2017 14:28:48 GMT

Hi, your estimation seems reasonable, you just have to add the header data.

First you have the L2CAP header. Then the 6LoWPAN and UDP header. I tried to illustrate this here:

L2CAP Header:
  Length          2 B
  CID             2 B
  SDU length      2 B
  L2CAP payload:
    6LowPAN IPHC  2 B
    Source addr   16 B
    Dest addr     16 B
    UDP header    1 B
      Src port    2 B
      Dst port    2 B
      Checksum    2 B
      Payload:
        Coap head 6 B
        Payload   Your data
        End       2 B
    
Sum               55 B

So the headers alone will require 2 additional packets.