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<title>Serial Communication</title>
<meta name="author" content="Ben Greenstein and Philip Levis" />
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+<div class="document" id="serial-communication">
<h1 class="title">Serial Communication</h1>
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-<div class="document" id="serial-communication">
<div class="note">
<p class="first admonition-title">Note</p>
<p class="last">This memo documents a part of TinyOS for the TinyOS Community, and
of this memo is unlimited. This memo is in full compliance with
TEP 1.</p>
</div>
-<div class="section" id="abstract">
-<h1><a name="abstract">Abstract</a></h1>
+<div class="section">
+<h1><a id="abstract" name="abstract">Abstract</a></h1>
<p>This memo describes the structure and standard implementation of the
TinyOS 2.x serial communication system for mote-to-PC data
exchange. The system is broken into three levels (encoding, framing,
the supported packet formats is platform independent, so PC-side
applications can communicate with arbitrary motes.</p>
</div>
-<div class="section" id="introduction">
-<h1><a name="introduction">1. Introduction</a></h1>
+<div class="section">
+<h1><a id="introduction" name="introduction">1. Introduction</a></h1>
<p>Users need to read data out of a TinyOS network. The most common
approach is to attach a mote to a PC or laptop with a wired
connection. While the interface on the PC side can vary from a serial
PC toolchain. This memo documents the protocols and structure of the
TinyOS 2.x serial communication stack.</p>
</div>
-<div class="section" id="serial-stack-structure">
-<h1><a name="serial-stack-structure">2. Serial Stack Structure</a></h1>
+<div class="section">
+<h1><a id="serial-stack-structure" name="serial-stack-structure">2. Serial Stack Structure</a></h1>
<p>The TinyOS 2.x serial communication stack is broken up into four
functional components. From bottom to top, they are</p>
<blockquote>
</blockquote>
<p>Structurally, they look like this:</p>
<pre class="literal-block">
- _____________________
-| |
+ _____________________
+| |
| Dispatcher | Packet formatting.
-|_____________________|
- _____________________
-| |
+|_____________________|
+ _____________________
+| |
| Protocol | Acknowledgements, CRC computation,
|_____________________| windowing.
- _____________________
-| |
+ _____________________
+| |
| Encoder/Framer | Translating raw bytes into frame
|_____________________| delimiters, escape bytes.
- _____________________
-| |
+ _____________________
+| |
| Raw UART | Platform code for reading/writing
|_____________________| bytes over the serial connection.
</pre>
3.4 describes how the default TinyOS 2.x implementation,
<tt class="docutils literal"><span class="pre">SerialDispatcherC</span></tt> does this.</p>
</div>
-<div class="section" id="the-2-x-serial-stack-implementation">
-<h1><a name="the-2-x-serial-stack-implementation">3. The 2.x Serial Stack Implementation</a></h1>
+<div class="section">
+<h1><a id="the-2-x-serial-stack-implementation" name="the-2-x-serial-stack-implementation">3. The 2.x Serial Stack Implementation</a></h1>
<p>Section 2 describes the basic structure of the TinyOS 2.x serial
stack. This section describes its actual implementation,
including SerialActiveMessageC, which sits on top of the Dispatcher.
All of the components except for UartC are part of the serial
library that lives in <tt class="docutils literal"><span class="pre">tos/lib/serial</span></tt>.</p>
-<div class="section" id="raw-uart-uartc">
-<h2><a name="raw-uart-uartc">3.1 Raw UART: UartC</a></h2>
+<div class="section">
+<h2><a id="raw-uart-uartc" name="raw-uart-uartc">3.1 Raw UART: UartC</a></h2>
<p>The UART HIL[<a class="reference" href="#tep2">TEP2</a>] is <tt class="docutils literal"><span class="pre">UartC</span></tt>, which provides a byte-level
interface to the underlying serial communication. It provides the
<tt class="docutils literal"><span class="pre">SerialByteComm</span></tt> interface:</p>
<p>It may provide additional interfaces for configuring the serial
port. This TEP does not consider this topic.</p>
</div>
-<div class="section" id="encoder-framer-hdlctranslatec">
-<h2><a name="encoder-framer-hdlctranslatec">3.2 Encoder/Framer: HdlcTranslateC</a></h2>
+<div class="section">
+<h2><a id="encoder-framer-hdlctranslatec" name="encoder-framer-hdlctranslatec">3.2 Encoder/Framer: HdlcTranslateC</a></h2>
<p>HdlcTranslateC is the serial encoder/framer. It uses the
<tt class="docutils literal"><span class="pre">SerialByteComm</span></tt> interface and provides the <tt class="docutils literal"><span class="pre">SerialFrameComm</span></tt>
interface:</p>
and sends an escape byte. When the escape byte is sent, it sends the
stored data byte.</p>
</div>
-<div class="section" id="protocol-serialp">
-<h2><a name="protocol-serialp">3.3 Protocol: SerialP</a></h2>
+<div class="section">
+<h2><a id="protocol-serialp" name="protocol-serialp">3.3 Protocol: SerialP</a></h2>
<p>The SerialP component implements the serial protocol using PPP/HDLC-
like framing (See RFC 1662[<a class="reference" href="#rfc1662">RFC1662</a>]). Type dispatch and buffer
management are left to higher layers in the serial stack. The protocol
be transmitted may begin spooling into SerialP while SerialP is
actively sending an acknowledgement.</p>
</div>
-<div class="section" id="dispatcher-serialdispatcherc">
-<h2><a name="dispatcher-serialdispatcherc">3.4 Dispatcher: SerialDispatcherC</a></h2>
+<div class="section">
+<h2><a id="dispatcher-serialdispatcherc" name="dispatcher-serialdispatcherc">3.4 Dispatcher: SerialDispatcherC</a></h2>
<p>SerialDispatcherC handles the data packets that the Protocol component
receives. It uses the SendBytePacket and ReceiveBytePacket interfaces,
and provides parameterized Send and Receive interfaces. The parameter
<tt class="docutils literal"><span class="pre">TOS_SERIAL_UNKNOWN_ID</span></tt> are reserved. New packet formats MUST NOT
reuse any reserved identifiers.</p>
</div>
-<div class="section" id="serialactivemessagec">
-<h2><a name="serialactivemessagec">3.5 SerialActiveMessageC</a></h2>
+<div class="section">
+<h2><a id="serialactivemessagec" name="serialactivemessagec">3.5 SerialActiveMessageC</a></h2>
<p>SerialActiveMessageC is a platform-independent active message layer
that operates on top of the serial communication
stack. SerialActiveMessageC is a configuration that wires
implementation {
components new SerialActiveMessageP() as AM, SerialDispatcherC;
components SerialPacketInfoActiveMessageP as Info;
-
+
Init = SerialDispatcherC;
Leds = SerialDispatcherC;
-
+
AMSend = AM;
Receive = AM;
Packet = AM;
AMPacket = AM;
-
+
AM.SubSend -> SerialDispatcherC.Send[TOS_SERIAL_ACTIVE_MESSAGE_ID];
AM.SubReceive -> SerialDispatcherC.Receive[TOS_SERIAL_ACTIVE_MESSAGE_ID];
-
+
SerialDispatcherC.SerialPacketInfo[TOS_SERIAL_ACTIVE_MESSAGE_ID] -> Info;
}
</pre>
} SerialAMHeader;
</pre>
</div>
-<div class="section" id="packet-format">
-<h2><a name="packet-format">3.6 Packet Format</a></h2>
+<div class="section">
+<h2><a id="packet-format" name="packet-format">3.6 Packet Format</a></h2>
<p>A data packet in the TinyOS 2.x serial stack has the following format
over the wire. Each protocol field is associated with a specific component:</p>
<pre class="literal-block">
____________________________________________
| | | | | | | |
- | | | | | | | |
+ | | | | | | | |
|_|_|_|_|_______________________________|__|_|
F P S D Payload CR F
-
+
F = Framing byte, denoting start of packet: HdlcTranslateC
P = Protocol byte: SerialP
S = Sequence number byte: SerialP
(P) is 0x40 (64), corresponding to <tt class="docutils literal"><span class="pre">SERIAL_PROTO_ACK</span></tt> (in Serial.h).</p>
</div>
</div>
-<div class="section" id="access-abstractions">
-<h1><a name="access-abstractions">4. Access Abstractions</a></h1>
+<div class="section">
+<h1><a id="access-abstractions" name="access-abstractions">4. Access Abstractions</a></h1>
<p>Two generic components: SerialAMSenderC and SerialAMReceiverC connect
to SerialActiveMessageC to provide virtualized access to the serial
stack. Each instantiation of SerialAMSenderC has its own queue of
services in the TEP 116, the serial component virtualizations provide
no snooping capabilities.</p>
</div>
-<div class="section" id="author-s-address">
-<h1><a name="author-s-address">5. Author's Address</a></h1>
+<div class="section">
+<h1><a id="author-s-address" name="author-s-address">5. Author's Address</a></h1>
<div class="line-block">
<div class="line">Philip Levis</div>
<div class="line">358 Gates</div>
<div class="line">email - <a class="reference" href="mailto:benjamin.m.greenstein@intel.com">benjamin.m.greenstein@intel.com</a></div>
</div>
</div>
-<div class="section" id="citations">
-<h1><a name="citations">6. Citations</a></h1>
+<div class="section">
+<h1><a id="citations" name="citations">6. Citations</a></h1>
<table class="docutils citation" frame="void" id="tep2" rules="none">
<colgroup><col class="label" /><col /></colgroup>
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projects / tinyos-2.x.git / blobdiff