TinyOS 802.15.4 Frames

+ +++ + + + + + + + + + + + + + + + + + + + + + +

TEP:	125
Group:	Core Working Group
Type:	Documentary
Status:	Draft
TinyOS-Version:	2.x
Author:	Jonathan Hui, Philip Levis, and David Moss
Draft-Created:	2-Feb-2007
Draft-Version:	1.1
Draft-Modified:	2007-04-03
Draft-Discuss:	TinyOS Developer List <tinyos-devel at mail.millennium.berkeley.edu>

Note

This memo documents a part of TinyOS for the TinyOS Community, and +requests discussion and suggestions for improvements. Distribution +of this memo is unlimited. This memo is in full compliance with +TEP 1.

Abstract

This memo documents the frame format for 802.15.4 packets in TinyOS +2.0.

1. Introduction

802.15.4 is a data-link and physical packet format for +low-power wireless networks that is used in many TinyOS platforms. +The TinyOS 2.0 active message layer adds a packet field for higher-level +protocol dispatch. This document describes the two TinyOS 2.0 frame format +for 802.15.4 networks. The first format is for isolated TinyOS networks; +the second format is for networks that share the spectrum with 6lowpan +networks[1]_.

2. 802.15.4

802.15.4 supports several different source and destination addressing +modes, and so has a variable sized packet header.[2]_ A TinyOS device MUST +support packet frames with 16-bit short source and destination addresses. +A TinyOS device MAY support additional 802.15.4 frame formats.

3. Frame Format

TinyOS has two 802.15.4 frame formats. The first format, the T-Frame, is +for TinyOS networks which do not share their channel with other wireless +networking archtiectures. This frame format assumes that TinyOS can use +every bit of the packet and does not need to state that it is a TinyOS packet. +T-Frame stands for "TinyOS Frame."

The TinyOS 802.15.4 T-frame format is as follows:

++-------------------+---------+------------------------------+--------------+
+| 802.15.4 Header   | AM type |            data              | 802.15.4 CRC |
++-------------------+---------+------------------------------+--------------+
+

AM type is a single byte field which indicates which active message type +the payload contains.

The second format, the I-Frame, is for TinyOS networks which share their +channel with 6lowpan networks. 6lowpan reserves a series of codes for the +first byte of the payload for non-6lowpan packets. In order to interoperate +with 6lowpan networks, TinyOS I-Frames specify such a field. I-Frame stands +for "Interoperable Frame."

The TinyOS 802.15.4 I-frame format is as follows:

++-------------------+---------+---------+--------------------+--------------+
+| 802.15.4 Header   | 6lowpan | AM type |        data        | 802.15.4 CRC |
++-------------------+---------+------------------------------+--------------+
+

AM type is the same as in a T-frame. 6lowpan is the IANA-assigned code +to identify this as a TinyOS packet. At this time, the exact value of +this code has not been determined. To inform 6lowpan that this is not +a 6lowpan packet, the code used MUST be in the range of 192-55.

4. Implementation

An implementation of the T-Frame can be found in tinyos-2.x/tos/chips/cc2420.

An implementation of the I-Frame will soon be found in +tinyos-2.x/tos/chips/cc2420.

5. Author Addresses

+

+Jonathan Hui

+657 Mission St. Ste. 600

+Arched Rock Corporation

+San Francisco, CA 94105-4120

+

+phone - +1 415 692 0828

+email - jhui@archedrock.com

+

+Philip Levis

+358 Gates Hall

+Stanford University

+Stanford, CA 94305-9030

+

+phone - +1 650 725 9046

+email - pal@cs.stanford.edu

+

+David Moss

+Rincon Research

+

+

+

+