serial protocol converters

July 7, 2009 at 12:00 am Leave a comment

serial protocol converters

See also FIXME serial ADCs and DACs.

RS-232 to PC keyboard (often called “wedges” — the most common versions allow you to plug a barcode reader FIXME barcode (RS-232) and a standard PC keyboard into the wedge, and then you plug the wedge into the keyboard port of a PC.)

Other protocol converters:

USB info (Universal Serial Bus)

Often used to transfer still images from digital cameras machine_vision.html#digital_cameras .


[FIXME: I know I have more MIDI info scattered elsewhere … move it here.]




SCRAMNet (Shared Common RAM Network) looks interesting.

MIL-STD 1553

MIL-STD 1553 is a military avionics bus.


  • Jan Axelson has lots of useful circuit board design information, and has written “Designing RS-485 Circuits” . Some people incorrectly put resistors at every node of a RS-485 network. There should only be at most 4 resistors hooked up to the twisted pair of wires: the terminating resistors (120 Ohm), one at each end of the wires; the biasing resistors (560 Ohm — use higher values for lower power consumption, lower values for better noise immunity on an idle line), at one end of the link, in parallel with the (inadequate) internal biasing circuit on most RS485 transciever chips (typically 100 KOhm pullup from A (noninverted) to +5V, and 100 KOhm pulldown from line B (inverted) to gnd). [DAV: What are implications of terminating with a series cap and resistor, rather than resistor alone ?] Jan Axelson claims that the rise time of the Maxim MAX3080 is slow enough (which limits it to 115 200 bps or less) that it doesnt need any terminating or biasing resistors for lines of less than 100 feet. “To comply with the specification, all of the nodes must share a common ground connection. This ground may be isolated from earth ground. … The RS-485 specification recommends connecting a 100-W resistor of at least 0.5 Ohm in series between each nodes signal ground and the networks ground wire” Jan Axelson recommends disabling the transmitter ASAP after the final stop bit has *started*, long before the end of the final stop bit, relying on hardware biasing to maintain the full stop bit. In fact, this article has a nifty 555 timer circuit that does just this — enabling the transmitter at the start of every logic “1” transmitted, and disabling the transmitter just after the start of every logic “0” “transmitted”. [FIXME: copy link to Jan Axelson to Embedded Web Server]
  • It seems that chips with built-in fail-safe protection try to force all unconnected-lines and lines-shorted-together to receive a logical 0 (the receiver indicates this with a hi output). Protocols (such as ASCII) should be designed to “park” the lines in this state as the last transmitted bit before disabling the transmitter.
  • From: “Cees” <cakoolen at>
    Subject: rs485 coding Delphi 3
    Date: 26 Jan 2000 00:00:00 GMT
    Organization: News Service (
    Newsgroups: comp.arch.embedded

    I am making a progam to communicate with a rs485 bus. The problem seems =
    to be that i have to disable the transmitter and enable the receiver at =
    the right moment. With the component i am using i cant see when the tx =
    register is empty, so i cant do that.

    pease help…!


    From: jan axelson <jan at>
    Subject: Re: rs485 coding Delphi 3
    Date: 26 Jan 2000 00:00:00 GMT
    Organization: @Home Network
    Newsgroups: comp.arch.embedded

    “Frederic Chaxel” <chaxel at> wrote:
    >I dont know using Delphi but if you can talk with the Windows device driver
    >(CreateFile, WriteFile, ReadFile, CloseHandle), you must set
    > fRtsControl = RTS_CONTROL_TOGGLE in the DCB structure
    >which is passed to SetCommState. Then RTS will automaticaly be
    >put high and low when bytes has to be send via the UART.

    >This signal is generaly used by simple RS232 to RS485 converter
    > in order to get the line or to put it in HiZ.

    Unfortunately, this doesnt work under W95 (knowledge base article

    There are various alternatives, some requiring supporting hardware:

    1. Keep the receiver enabled and read back what you sent to find out
    when its OK to disable the transmitter (by controlling the line in

    2. Use various hardware schemes to control the transmit-enable

    3. Use a delay timer to estimate the needed time, with a margin of
    error, and control the line in software.

    I have many links to RS-485 information at:

    Jan Axelson
    jan at

    [Option #1 is highly recommended by article
    ____ [FIXME] in _Embedded Systems_ by Nigel]

  • Annoying — why are the output pins on the standard 75176 RS-485 Transceiver “swapped” ? It would be so convenient if the inverting input (that I want to bias with a resistor to ground) were next to the ground pin, and the noninverting input (that I want to bias with a resistor to +5V) were next to the +5V pin, but no — they are exactly the opposite.
  • Dynamic Engineering sells a PCI card that connects to 13 (!) RS485 bidirectional signal pairs. (It is powered by a Altera FPGA).
  • [FIXME] has a interesting diagram of turn-around time at .
  • Has (well-drawn) schematics.
  • <!–
  • –>



  • –>

  • “MDs webSite got a piece of code doing this.. its a part of eMON86. Its free(?) erh… at leat, U can go downloading it….”
  • From: bobgardner at (BobGardner)
    Subject: Re: RS-232 Autobaud
    Date: 26 Nov 1999 00:00:00 GMT
    Newsgroups: comp.arch.embedded

    >Does anyone know an afficient way to implement a simple autobaud algorithm
    >over serial port?

    Make a table of what a carriage return looks like at all the baud rates you
    want to recognize.

  • From: tony <Fuzzy_Wombat at>
    Subject: Re: RS-232 Autobaud
    Date: 27 Nov 1999 00:00:00 GMT
    Newsgroups: comp.arch.embedded

    Easiest thing, if your micro lets you, is to
    turn the UART off (make it into a normal port pin) and actually _time_
    the bit lengths.


  • From: jan axelson <jan at>

    Subject: Re: RS-232 Autobaud
    Date: 29 Nov 1999 00:00:00 GMT
    Newsgroups: comp.arch.embedded

    1. One end repeatedly sends a character, which may be anything from
    Chr(0) through Chr(127), at the desired bit rate. (The MSB, which is
    the last character sent, must be 0.)

    The other node tries to detect the character, beginning at its highest
    bit rate. If the receivers bit rate is too high, it detects more than
    one Start bit for each character sent. When the receiver detects the
    correct character and no others, without framing errors, it has the
    correct bit rate and can send a code to acknowledge.

    2. If the receiver can measure the received bit widths, the sender can
    send a predetermined character and the receiver can measure the widths
    of the signals and calculate the bit width from there. This the method
    used by the 8052-Basic chip, which looks for a carriage return.

Barker code

some links I stumbled over on a quick search of Google for Barker code info.

  • “Barker Code Position Modulation for High-Rate Communication in the ISM Bands paper by Israel Bar-David and Rajeev Krishnamoorthy in _Bell Labs Technical Journal_ 1996-08 “A new modulation and transmission scheme … BCPM … In the example discussed… the data rate is quadrupled from 2 to 8 Mb/s. Algorithms to decode BCPM signals efficiently in the presence of inter-symbol interference are also described.

    “The 11-chip Barker code (+ + + – – – + – – + -) specified by the IEEE 802.11 standard

    I. Bar-David, “A Method and Apparatus for Spread Spectrum Code Pulse Position Modulation, U.S. Patent applied for August 1994 to be issued early 1997.

    I. Bar-David, and R. Krishnamoorthy, “A Spread Spectrum Code Pulse Position Modulated receiver Having Delay Spread Compensation, U.S. Patent applied for 1994-11 to be issued early 1997.

  • some other Barker codes: 7 + + + – – + – 11 + + + – – – + – – + – (specified by the IEEE 802.11 standard ? — Israel Bar-David 1996) 11 + – + + – + + + – – – (specified by IEEE 802.11b — Joel Conover 2000-07 ) [FIXME: post list (or a pointer) in response to the question on page . Stick “askprofscience in periodical.html ? or unknowns.html ? ]
  • “Linear Complexity of Kronecker Sequences letter by Kari H. A. Kärkkäinen 2001-05 lists these Barker codes:
    • 2: 1 0
    • 3: 1 1 0
    • 4: 1 1 0 1
    • 4: 1 1 1 0
    • 5: 1 1 1 0 1
    • 7: 1 1 1 0 1 0
    • 11: 1 1 1 0 0 0 1 0 0 1 0
    • 13: 1 1 1 1 1 0 0 1 1 0 1 0 1

    “linear complexity (LC) … is the degree of shortest linear feedback shift-register generator that generates the same sequence.

    and mentions these bit sequences (linear PN codes): Gold codes, small set of Kasami, large set of Kasami, Barker codes, Golay complementary, maximum-length sequence.

    mentions the importance of rapid synchronization. (similar to clock recovery).

  • uses Barker codes to look at meteorites … is there a better explaination of this technique ?
  • “Youve seen lots of theoretical and tutorial articles and information about RF & Spread Spectrum. But have you seen much practical, hand-on, “how to” info? Probably not — so here it is! This page is the home of highly practical stuff about spread spectrum & RF design. “ .. Simple & foolproof 5 stage maximal linear sequence PN generator. … Generate the IEEE 802.11 WLAN 11 bit long Barker code with a 16V8A PAL/GAL based PN Generator. (… run either forwards or backwards, by using the REV pin control function.) … Generate any PN code or arbitrary sequences up to 16 bits long. Uses dip switches for data and sequence length. … Several ways to interface PN generators to Doubly Balanced Mixers to generate DSSS BPSK. … The advantages of Constant Envelope Modulation (CEM) … Some very useful short PN Codes with low cross-correlation. An SSS sidebar – short subject with 3 bit Gold and 4 bit Kasami codes listed. … Optimum Frame Synch Patterns [FIXME: protocol] … Introduction to Oscillator Design … Technical Topic: All About Correlators [FIXME: read]
  • ECE 487 asks

    2. A receiver is matched to a single 7-baud binary Barker code (+ + + ¡ ¡ + ¡ ). (a) What will be the output of the filter if the input consists of two contiguous (“touching”) Barker codes, each of length 7, assuming no Doppler shift? (b) Repeat (a) for the case when the two codes are separated by exactly one baud length and the second is inverted in sign; i.e., the input sequence is (+ + + ¡ ¡ + ¡ 0 ¡ ¡ ¡ + + ¡ +). The receiver decoder (filter) remains the same as for (a). You should notice that some of the range sidelobes disappear in the second case. These sorts of probing sequences are used in ionospheric remote probing experiments at Arecibo and other large “incoherent scatter” radars. 3. Because of its very slow rotation rate, it is possible to map essentially the entire surface of Venus using the delay-Doppler technique. Mars, on the other hand, rotates as fast as Earth does, with a Martian “day” equal to 1.03 Earth days, and so the planet is “overspread”, meaning that one cannot simultaneously avoid range and frequency aliasing over the whole surface of the planet. It is possible to map a portion of the surface fairly well, however. Suppose we decide to ignore the range aliasing for the leading portion of the return (from points near the subradar point), because the echo strength falls off rapidly with delay. In other words, when we are receiving echoes from two (or more) range “rings” on the planet simultaneously, the echo from the nearest ring will dominate, and the “clutter” from the farther ring (or rings) will not cause too much degradation of the signal.


  • –>


Think serial communication is serious ? Hah.


  • “Next Generation I/O” for Servers The Link Architecture Specification is online here. “defined to handle a full duplex Gb/s link over short haul copper or fiber optic media” 8 conductors. 4 of the conductors are data: A differential transmit signal, a differential receive signal. The other 4 signals are optional: power, ground, module fault detect, and optical power loss detect, which can be used by a opto-electronic converter module.
  • Fieldbus “fieldbus and related industrial networking technologies.” HART (Highway Addressible Remote Transducers ) superimposes digital data on a 4-20mA current loop … 2-way comms … This digital protocol uses a low-level FSK sinewave whose average value of zero has no effect on the analog signal and runs simultaneously with it. … 1200 and 2200 Hz mark/space frequencies … 1200 bps … simultaneous analog/digital mode works in a point-to-point topology … all-digital mode allows multidrop topology [and] 2 masters and as many as 15 devices connected to the same cable …
  • InterBus-S (European standard DIN 19258) “The only web site dedicated to [InterBus-S] is in German.” “To a programmer, the bus looks like a shift register … up to 8 miles … The maximum I/O count on the bus is 4096 points, and with that number a total network scan requres 14 msec.” “3-pair twisted wire … 5 twisted pairs …”
  • Profibus (European standard DIN 19245) “2-conductor twisted pair … maximum bus length without a repeater is 100 m at 12 Mbps … at 93 Kbps, max cable length is 1.2 Km. … ”
  • Open DeviceNet Vendor Association, Inc. (ODVA) (Allen-Bradley developed the DeviceNet spec then turned it over to ODVA in 1995). “Its comm link is based on … CAN (controller area network), originally developed by Bosch for the European auto market to replace wire harnesses with low-cost network cable. … DeviceNet supports 64 nodes, each working with an infinite number of I/O points with transmission rates to 500 Kbps over 100 m … The topology is a linear bus consisting of a trunk line with drop lines; power and signals run over the same cable. Bus addressing is peer-to-peer with multicast, multimaster and master/slave setups possible. Because of the bitwise arbitration used during power-up and certain messaging types, the bus doesnt lend itself to repeaters. …”
  • LonWorks from Echelon Corp. Raytheon produces fiber-optic interfaces for Neuron processors that use the Echelons standard LonTalk network protocol. (the integrated “DFOC – Dual Fiber Optic Control Node Card” | or the external fiber-optic interface
  • The Readout Instrumentation Signpost Measurement, Control and Automation Resources throughout the World
  • Steve ONeil has collected lots of good pointers to network bus systems .
  • lots of Mac and PC and modem serial port information
  • connecting the Joystick port to a MIDI cable
  • ($13) 32035 Hayes Modem Cable (DIN-8 M to DB25 M)
  • Cassiopeia-to-Mac Connectivity

    “Connectix (Virtual PC), Casio (Cassiopeia), and Microsoft (Windows CE) all told me it couldnt be done, but I just synchronized my HPC (a Casio Cassiopeia Windows CE machine) with a Power Macintosh running Virtual PC. ”

    The serial cable that comes with the Cassiopeia has a 16-pin connector on one end, and a DB9 (female) connector on the other. You will need to add to it:

    • 1.A serial com port adapter, DB9 (Male) to DB25 (Female) ($7.99 at Frys).
    • 2a. A Hayes Modem cable (NOT a null modem cable), DB25 (Male) to Mini-DIN 8 (Male) ($6.95 at Frys).
    • 2b. Alternatively, the cable provided with the Casio QV cameras which they supply to enable connection of their camera cable to a Mac serial port worked fine for Adel Malek, MD, PhD (thanks, Adel), and can be ordered from Casio. It makes for a very short simple adapter (only about 5-6 inches long).

    NOTE: A printer cable doesnt work — not enough of the pins are connected. And neither does the adaptor cable that comes with the Palm Pilot Mac Pac (Michael went back and forth between it and the configuration above several times, and the adapter always failed). “Yeah, but its DB9 to mini-DIN 8 — it should work!”. Go ahead; its your time to waste. If anyone finds a large-supplier source for a DB9 to Mini-DIN 8 connector that correctly does the same thing as 1 and 2 together, PLEASE let me know so I can update this page.

    “Windows CE Serial Port FAQ” by Chris De Herrera

  • ($7.75) I-66H: 6FT Mac serial modem cable DIN8M/DB25M
  • ($8.98) Mac to High Speed Modem Cable 6ft item #M 82598 Six-foot MiniDIN 8 male to DB25 male, Apple Macintosh to high-speed modem, hardware handshaking cable.;act_type=DSR
  • ($11.98) MAC MODEM CABLE MD8M-DB25M 10FT W/HANDSK item #M 82597 10-foot MiniDIN 8 male to DB25 male, Apple Macintosh to high-speed modem, hardware handshaking cable uses high speed jumpers.;act_type=DSR
  • From: <cmpethic at> (Chris Pethick)
    Newsgroups: comp.sys.mac.comm,comp.sys.mac.programmer.misc
    Subject: Re: PowerMac serial port
    Date: 26 Jan 1995 23:25:15 GMT
    Organization: Intel Corporation

    > My question: can the PowerMac actually handle the speeds I am looking for,
    > and if so, how? Are there utilities for this, or will I have to write my
    > own device driver to reach these speeds?

    The PowerMac serial port can indeed handle the speeds you are talking
    about. However, the only way I know to get those speeds is to provide
    an external clock signal on the DTR line of the serial port in
    question. There is a serial driver control call which enables
    externally clocked mode. This call is documented in one of the Tech
    notes. In order to get your desired 64000 char/sec you will need to
    clock the port at about 640KHz (or more). The PowerMac serial ports
    are capable of handling several megabaud in this fashion.

    Chris Pethick

  • 9 June 1989 Inside Macintosh, Volume II (pages 250-251) tells how to configure for eleven baud rates: 300, 600, 1200, 1800, 2400, 3600, 4800, 7200, 9600, 19200, and 57600.
  • Article Last Reviewed: 9 June 1992 o Port A on the Macintosh SE and Port A on the Macintosh II support synchronous transmission, but Port B does not. Earlier Macintosh products do not support synchronous transmission through either port. Copyright 1991, Apple Computer, Inc.
  • Doug says the MIDI device his company sells uses external clocking. From: <doug at> (Doug Wyatt) Newsgroups: comp.sys.mac.comm Subject: Re: infinite speed on serial line Date: Wed, 07 Feb 1996 15:50:33 -0500 Doug Wyatt music software
  • From: “Peter Zechmeister” <zechm002 at>
    Subject: Re: Proposal for a Home Automation protocol using PIC 16C84, RS485, and Linux.
    Date: 04 Sep 1999 00:00:00 GMT
    Organization: University of Minnesota, Twin Cities Campus
    Newsgroups: comp.home.automation,comp.arch.embedded

    Check out “S.N.A.P – Scaleable Node Address Protocol”, its a protocol for networked
    PICs etc, that can be connected to PCs, and is mapped onto TCP/IP, so …… dream on

    Peter Zechmeister – <zechm002 at> – A University of Minnesota Alumni

  • ???
  • USB device with serial interface
  • “Serial Backplanes Transport Designers To The Analog Zone” article by Craig Prunty and Tom Palkert
  • “Future Computing: The Serial Bus Revolution Takes Off Serial Buses Play Well Outside The Box, But May Have A Hard Time Creeping Inside.” article by Jeff Child has nice chart on the cost per I/O bond pad. Lots of cool speculation.
  • Only if you put the destination address near the beginning of the packet is it possible to cut-through switch, rather than store-and-route.
  • the Consumer Electronics Manufacturers Association (CEMA) published the EIA-709 standard for home networking.
  • From: Dmitri Katchalov <dmitrik at>
    Subject: Re: RS232 without flow control?
    Date: 27 Jan 2000 00:00:00 GMT
    Newsgroups: comp.arch.embedded,sci.electronics.basics,

    > > So am I crazy in not incorporating any flow control (RTS/CTS,
    > Well, it depends on the data format!

    > If you miss a character in a decimal number, it is not the
    > problem that you have NO data, but wrong data. How would you
    > distinguish missing decimals? The same applies to multibyte
    > binary data.

    Easy. Youll get FIFO buffer overrun bit set in your UART.

    You will need a unique char sequence to identify the start of
    transmission so the receiver can re-synchronise after buffer overrun.
    If youre sending ASCII <CR> seems like a good choice.


    Sent via
    Before you buy.

  • Quatech sells multi-port serial and parallel adapter cards, analog and digital data acquisition cards.
  • RocketChips is a leading developer of ultra-high-speed CMOS mixed-signal transceivers “Serial backplane architectures are expected to grow from 5 percent to 100 percent of network system architectures over the next few years.”
  • “Automatic Baud Rate Detection For The 80C51”
  • Embedded Communications by Philip Koopman “Survey of Communication Protocols for Embedded Systems”, pointers to USB, CAN, LonTalk; “Time Division Multiple Access Without a Bus Master (JTDMA) (a robust, master-less communication protocol)”
  • Open Tape Format Specifications data compression and error-correction codes… ??? More technical details: “open tape format specifications that allow widespread manufacturer participation and extensive options for buyers. … protect the interests of manufacturers and buyers alike. … The LTO program initiative is an example of co-opetition at work. New opportunities are being created for both customers and manufacturers.
  • has some introductory information on serial links (synchronous and asynchronous)
  • Serial ATA: The Unnecessary Standard “The ideas behind Serial ATA are quite sound. The problem is that there is already an existing standard which accomplishes all that Serial ATA does, and much more, and is not inherently any more expensive.

    That standard is IEEE-1394, also known as FireWire or i-Link. — Eric Smith 2000-02-16

  • _Serial Communications: A C++ Developers Guide_ book by Mark Nelson ??? This is narrowly focused on writing Windows programs that use the PC serial port.
  • “In protocol design, perfection has been reached not when there is nothing left to add, but when there is nothing left to take away. [fixme: design; procotol; serial ??]
  • how the onHand pins match to the serial port on the desktop — Johan
  • Project MART (Mobile Ad-hoc Routing Testbed)

    In MANET, every host is also an IP router for the other MANET hosts. This enables users to access the wired network using other users mobile hosts as relay stations beyond the direct wireless link-level (radio) range of the destination host. Also, with the MANET approach, the hosts are not tied to one link-level technology, and their IP addresses are not restricted to one subnet. With this technology, a cost-efficient broadband access to the Internet can be provided. However, the technology is not yet ready; issues like security and distribution of costs must be addressed.

    DAV: this is obviously far more scalable than most wireless networks … Is this related to ?

  • buzzwords: BCPM (Barker code position modulation) QAM (quadrature amplitude modulation) CDMA (code division multiple access) BPSK (binary phase shift keying) DBPSK (differential BPSK) QPSK (quarternary (sp?)/quadrature phase shift keying) DQPSK (differential QPSK) OQPSK (offset quarternary (?) phase shift keying) TPSK (trinary phase shift keying — David Cary did some back-of-the-envelope calculations that indicate TPSK is superior to BPSK, QPSK, QAM, and all other possible modulation schemes in a bits/watt sense under certain conditions … but I havent seen anyone else even consider the possibility.) DSSS (direct sequence spread spectrum) FHSS (frequency hopping spread spectrum) OFDM (orthogonal frequency division multiplexing) PPM (pulse position modulation) GFSK (Gaussian frequency shift keying)[FIXME: huh ?]
  • [protocol] by Joel Conover 2000-08 has a pointer to “”IEEE 802.11 Packet Structure” graphic, and, for comparison, “Ethernet Packet Structure”
  • IEEE 801.11b “ Here you can find the complete source code, build environment, and instructions for flashing an 802.11 access point with linux 2.4.17. The end product is a linux-based access point providing full wireless services, including multipoint to multipoint wireless bridging (802.1d), while at the same time distributing fully standard 802.11b connections to end users.
  • Turbo codes are a forward error correcting code technique data_compression.html#turbo_codes
  • “pilot symbols AKA “static header AKA “guard bars
  • goes into details of a spread spectrum RF communications protocol, implemented on one chip (!). This looks suspiciously similar to a Microchip PIC chip. Has a cool graph of current vs. time, giving quantitative numbers for current and time in each state: sleep (1 uA), wakeup, receiver and processor on (12 mA), receiver off (reply processing), transmitter on, all off (sleep). Apparently it pulls the highest current when receiving (many transcievers pull the highest current when transmitting).
  • [FIXME: check this out. Seems to have lots of information. spread spectrum, ultra-wideband, optronics, asics, etc.].
  • “Easy-A Multidrop Communications Protocol | has a few good points that apply to simple protocol design. Argues against using “line idle to mean anything special — because that makes it impossible to test devices manually from a dumb terminal. Argues that reserving a special “escape character is the best way to indicate “the next byte is an address byte. (Superior to using “line idle) (superior to using a “9th bit since many devices cant transmit or receive a 9 bit character) (superior to using the hi bit “8th bit because it transmits more data bits / character … except for very, very short packets). Suggests the 6 pin shielded Mini-DIN connector … 3 pairs: transmit 422, receive 422, and AC power. “It is easy to see why there are no [simple] protocols in use. It is too easy to be drawn into “adding just one more feature” which in turn adds one more set of exceptions and one more set of complications and limitations.
  • “Ask the Guru: IBM/LaserWriter Interfacing article by Don Lancaster 1990-02

    Figure two shows you the six most popular IBM to LaserWriter cable lashups. The six combinations result since you can have a DB-25 or DB-9 connector on the host and a DB-25 using RS-232-C or (depending upon your LaserWriter model) a DB-9 or a Mini DIN-8 connector using the RS-423 interface serial standard.

  • [protocols ?] Local Interconnect Network (LIN) Demonstration
  • TechHome Guide to Home Networks has a quick description (with links to more details) of these power line networking groups:

    CEA R7.3 (Consumer Electronics Association); HomePlug Alliance; HomePNA (Home Phoneline Networking Alliance); X10; CEBus; LonWorks;

    and some wireless (RF and infrared) media protocols. [FIXME: machine vision ?]

  • has some information on power line networking
  • recommended this page. That makes me happy :-).

    The design fits 26 letters of the alphabet, the * and #, 10 numbers, three punctuation keys, a space bar, shift and delete key into an area no larger than one-third of a business card.

    … Digit Wireless founder David Levy … Fastap …

    Digit Wireless has also developed a version for Japan that allows the keyboard to represent the 120 characters of the countrys languages.

    Mr Levy said it reduced the number of taps needed to form Japanese characters from eight to two.

  • [protocol ?]

    Mount Rainier enables native OS support of data storage on CD-RW. This makes the technology far easier to use and allows the replacement of the floppy. This is done by having defect management in the drive, by making the drive 2k addressable, by using background formatting, and by standardizing both command set and physical layout. The new standard is promoted by Compaq, Microsoft, Philips, and Sony and is supported by over 40 industry leaders

  • Glove-Talk (Is this related to glove-input virtual keyboard ?) “Glove-Talk: A neural network interface between a data-glove and a speech synthesizer. article by Fels, S. S. and Hinton, G. E. (1992) and (1995)
  • Wristwatch gives remote control of computer 17:38 08 October 01

    The GestureWrist, developed by Jun Rekimoto of Sonys Computer Science Laboratory in Tokyo, Japan, uses sensors embedded into a normal watch strap. These track a wearers arm movements and the opening and closing their hand, relaying this information to a computer kept somewhere on their person.

    The result is that, instead of relying on a computer mouse, the wearer can move a pointer around a computer screen and click on icons using only arm and hand movements.

  • [keyboard ergonomics] November 22, 2002 Custom Keyboards For Individual Applications By Dave Salvator,3973,720151,00.asp
  • S-ATA (Serial ATA) [FIXME:] a photo of 2 S-ATA connectors on a motherboard:,3973,537599,00.asp A review of a serial ATA hard drive
  • “PCI Express is supposedly going to replace the previous PCI connector. pictures of the connector (much smaller than PCI connector),3973,530651,00.asp
  • Programming the Keyboard
  • [FIXME: move to parallel interfaces] Of course we are not limited to 2 disk drives. RAID-5 (the most common type) requires at least 3 physical disk drives, and often file servers have 5 or more disk drives. Most motherboards (most Intel, and a lot of newer PPC) have 2 IDE headers, and a ribbon cable connects each header to 2 drives (for a total of 4). So how do we get 5 hard drives, plus a CD drive for a total of 6 drives ? Simple — we buy an IDE card or a SCSI card and plug more drives into that. Many PPC motherboards have a SCSI connector. Up to 7 external devices can be daisy-chained through the SCSI connector, so its simple to connect 5 hard drives and a CD-ROM to the SCSI chain.
  • [FIXME: quote from this in my rant about scalability]
  • Appendix C: Serial Communications on EIA-232 (RS-232) has some details on voltages, etc. of RS-232, and some information on its limitations and successor standards that overcome those limitations.
  • Date: Thu, 19 Dec 2002 09:52:49 +0000
    To: pci-sig at
    From: Paul Walker <paul at>

    Reply-To: Paul Walker <paul at>
    Subject: Re: Whats your bus?


    A common feature of the ones you mention is that they are not buses, they use switch fabric.

    So does SpaceWire, a derivative from IEEE 1355, that is simpler and more flexible than any of those you mention. It was way ahead of its time, but the plethora of new standards, all of which follow it and all of which are more complicated, just show that its time will come.

    You can reach most of the information about SpaceWire and IEEE 1355 from our web site:

    Best regards

    Paul Walker

    … Alan Deikman <Alan.Deikman at> writes
    >Id like to hear back from anyone with an opinion on this. What do you
    >think of as the ultimate bus after PCI and why?

    >1. Hypertransport
    >2. RapidIO
    >3. Star Fabric
    >4. PCI Experss
    >5. Infiniband
    >Any others that will be players? I get asked this sort of question all the
    >time and I need some new material. 🙂
    >Alan Deikman
    >ZNYX Networks, Inc.

    Paul Walker
    CEO, 4Links Limited, Chair of the 1355 Association

    <paul at>

    4Links Limited — Boards, chips, IP and consultancy … for Links
    P O Box 816, Bletchley Park phone +44 1908 64 2001
    Milton Keynes MK3 6ZP, UK fax +44 1908 64 2011

  • Line Quality Repair advice on cleaning copper terminals and RJ-11 jacks.

    Is there a standard for connecting the TX, RX, GND of RS-232 to the 4 pins of a RJ-11 connector ? Paul Campbell says “I wired the GND to the yellow line, TXD to the black line and RXD to the red line.”

  • ??? [keyboard]
  • lists lots of unusual keyboards (some of them only work when plugged into a PC; others are “laptop replacements”) [FIXME: #Dana]
  • SERCOS: serial real-time communication system ???
  • data synchronization protocol. Here is one way to implement it:

    Every “record” is tagged with a (local) time. Every time it is *modified*, the time is reset to (local) “now”. (A “record” could be an entire file, or it could be a single row in a database).

    Each “record” is tagged with a name. It might be nice if this name is a globally unique number. (Perhaps the ethernet number of the machine it was created on, plus some sequence number to distinguish all the records ever created on that machine). (Sequence number can be the same as what the clock of the machine where it was created said at the instant it was created — which may be *different* from the “time” tag, because of both (a) local time doesnt align with the time at the machine where it was created, and (b) the record may have been modified.)

    Every machine keeps track of everyone it has ever synchronized with, and exactly when that happened (local time).

    During synchronization (while synchronizing):

    * Check to see that “local time” on this machine and “neighbors time” on other machine seem reasonable — At minimum, “local now” should be *after* “local last-time synchronized with that neighbor” on both machines. Perhaps it would also be nice for each side to find the *time* since the last synchronization using local data, and make sure both side agree on roughly the same elapsed time. Perhaps go even further and make sure “now” is roughly the same on both machines (if they are both supposed to be synchronized to GMT).

    The very *simplest* thing to do is simply send *all* my data over. While recieving *all* my neighbors data, I should see:

    * “old, unchanged data, the same on both sides”: The copy I send over has a date *before* the last time I exchanged data with that machine. The copy he sends back has a date *before* the last time he exchanged data with me. (If were both synced to GMT, both copies have the *same* date). Doesnt really need to be sent. Already the same on both sides.

    * “new items created on my side”: The copy I send over has a date *after* the last time I exchanged data with that machine. He never sends me a record with that name.

    * “new items created on his side”: He sends over a copy with a (remote) date *after* the last (remote) time I exchanged data with that machine. I dont have any records with exactly the same name. I store it with some arbitrary local time *before* “now”, perhaps (now – 1 tick), perhaps some approximation of the (GMT) time it was created.

    * “items that were deleted on my side”: He has an old copy dated *before* the last time I exchanged data with that machine. I dont have any records with exactly the same date. Delete record on both sides.

    * “items that were deleted on his side”: I have an old record dated *before* the last time I exchanged data with that machine. He doesnt have any such record. Delete record on both sides.

    * “items that were modified only on my side”: I have a record with a modification date *after* the last time I exchanged data with that machine. He may have a record with a (remote) date *before* the last (remote) time I exchanged data with that machine. Replace his obsolete record with my newer record.

    * “items that were modified only his side”: similar.

    * “other — conflict”: something odd happened. Keep both copies of the record; try to get the user to merge them into one new (freshly-modified) version. (What exactly is the situation(s) here ?)

    Will this really work if we have *3* or more machines trying to synchronize with each other (pairs at a time), where any record can be modified on any machine ?

  • the serial ports DSR input will detect either polarity, so I dont know why youre worried. See my file on my websites FTP Gateway: which tells how to directly access those pins logically from program control. -Steve — -Steve Walz -Electronics Site!! 1000 Files/50 Dirs!! Europe:(Italy) <!–

  • –>


Entry filed under: Communications.

A-301 High Voltage Amplifier/ Piezo Driver and Modulator2

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