Network I/O Protocols
The OSI Network Reference Layers,
The difference between a "serial bus" and a "serial interface" and a "network
protocol" is blurring -- see busses (Modbus,
X10, USB, MIDI, etc.), serial IO (RS485,
frank23 at ~NOSPAM~softhome.net
YASP: A simple and open protocol for building networks with small
* Adresses length: 1 to n bytes
* Medium access: CDMA/CS/NDA (Carrier Sense Multiple Access / Collision Detection
/ Non-Destructive Arbitration)
* Addressing modes: unicast, broadcast and multicast
* Smallest frame: 6 bytes
* Error detection: CRC16
* Physical layer: 1-wire "open collector" or 2-wire diferential (CAN
* Current PIC implementation: about 480 words of code and 25 bytes of RAM
* License: LGPL
The Network Administrators
Guide by Olaf Kirch
"Practically Networked has provided practical, easy-to-understand help for
small network builders since early 1998"
Selecting A Home Network Kit - Choose The Right Tools For Putting PCs In
Tiny Embedded Network
LON - http://www.lonmark.org
peer-to-peer serial protocol. It supports heirarchical addressing (scalable
up to 32K nodes in a logical network), multi-drop, multiple media - twisted
pair, RF, Fiber, powerline (or a mix of media in a logical network). Since
it is peer-to-peer, every node can act as a master or you can implement a
mult-master architecture. The protocol is done and implemented in silicon
available from multiple sources. Echelon wants to charge $5 per node (!)
for use and restricts doc's/changes spec to enforce this.
The powerline version of the physical layer is starting to exceed 10Mbit/s,
blowing away the 120 bit/s of X10, and there are physical layer specs for
RS485, RF, IR, etc. The problem of custom chips is still there, but the price
is reasonable, and there are at least a couple sources. Also, there is huge
buy in as this is supposed to be the new home automation standard. Lucent,
Cutler Hammer, and Microsoft, to name a few.
CEBUS packets allow the addressing of 0xFFFF homes with 0xFFFF nodes, sending
256 bytes data per packet. Data is context sensitive. ie. A TV will have
volume up/down power on/off channel up/down pip on/off etc. A light switch
will have power on/off dim up/down. Thus your packetization is as simple
as your device and doesn't require a big micro implementing 17 software layers
to turn on a light bulb!
For an example product, see
http://www.intelogis.com They make
a powerline peer to peer networking solution for sharing data between 2 computers
and sharing a printer. 10Mbit over power line, $99 for the package. And they
now have an open source
SNAP - http://www.hth.com/snap/ free
and open , easy to learn and light weighted network protocol
HDLC - Very mature.
FLAG ADDRESS Payload CRC FLAG
(8bits) (0-16Bits) (8 * N Bits) (16 Bits) (8Bits)
The flag is a fixed byte (often 0b01111110 or 0x7E)
The flag must be escaped if it appears in the data stream.
Ken Websters PIC16C74 serial port
multiplexer. This includes a packet system with addressing, control,
checksums, etc... Actually almost a network (OSI 3) system.
| ||©2020 These pages are served without commercial sponsorship. (No popup ads, etc...).Bandwidth abuse increases hosting cost forcing sponsorship or shutdown. This server aggressively defends against automated copying for any reason including offline viewing, duplication, etc... Please respect this requirement and DO NOT RIP THIS SITE. Questions?|
<A HREF="http://www.massmind.org/techref/networks.htm"> Network protocols</A>
Welcome to www.massmind.org!