TD-USB-01: USB Mouse Interface TD-USB-01 interface with mouse sensor board.  This is an example USB project showing how to interface an optical mouse sensor (the ADNS-2620) with a standard XP/Vista computer.  The TD-USB-01 board with a PIC18F2550 communicates with:   the PC: USB 2.0 through a mini-B connector;  the mouse sensor board: SPI over 4-wire flatcable. __ Designed by Michel Bavin

Technique Makes Low Cost PC-Board Shields 02/19/04 EDN-Design Ideas Many pc-board assemblies require shields to reduce susceptibility to interference from electromagnetic fields.  A classic example is a radio receiver, in which the front end usually needs high isolation from the tuning synthesizer.  Historically, shields for low-volume or low-cost applications involve trade-offs.  You can't justify the cost of a custom-cast shield, and shields machined from aluminum burn through money as fast as the end mills go dull.  You can make a simple shield for just a few dollars by using commonly available die-cast aluminum "project boxes, " such as those from Hammond Manufacturing (www.  hammondmfg.  com).  These boxes come in sizes from 2×2 in.  to more than 7×4 in.  You turn the project box into a shield by sandwiching the pc board between the top and the bottom of the box, thus completely enclosing the sensitive circuitry.   Design by Steve Hageman, Windsor, CA

TEK 5000 Modules in TM500 frame After getting a cheap PS5010 in good shape from eBay, I needed to make it work on my TM500 mainframe.  Since TM500 modules can be used on TM5000 mainframes, I thought the reverse should be also possible.  I found some references on the web and newsgroups, but no details on how to do it.   __ Designed by Roberto Barrios EB4EQA

Telecard reader Attention!!! This circuit its only a reader its not programmer.  You CANNOT refill, hack or any illegal thing, the telecards.  The purpose of this circuit its to understans how a microcontroller read, serial, the telecard, to build some other

Telecard reader This telecard reader can read the contain of any  telecard until 64 bytes (512 bits) and display it  to  hyper terminal software, using RS232 port __ Designed by © Vassilis Serasidis

TempBug-- Internet-Connected Thermometer 26-Jun-14 -Design News:   Last January, we had some trouble with the heat in my office -- specifically, the kind of trouble wherein the heat is not on, you turn it up, and it is still not on.  This went on for more than a few days and finally ended a day or two after we got an email announcing that the heat was broken and __ Gadget Freak-Case #257

Temperature Measurement Measures temperature via SMT160-30, shows it on LCD and communicates with RS232 (sends values of temperature to terminal 

Test & Development Tool for DS Interface (Data transfer via handshake test tool) The DS protocol was designed to provide firmware-based bidirectional host-to-slave inter processor communications for situations in which no hardware solution is available and the host and/or the slave in incapable of tending the interface in real time.  The only specialized hardware required is two bidirectional I/O ports on each chip (alternatively two input ports and two tri-statable output ports may be used.  In other words, it provides some of the functionality of the Two-Wire-Interface (TWI, or I2C as named by Philips) where an actual TWI is not feasible in either hardware or firmware.   __ Designed by Dick Cappels

The 89Sxx Learning Board Build a simple and cheap 89Sxx MCU learning board by Tahan Prahara, Indonesia __ Designed by Wichit Sirichote

The 8-Way Relay Board This board is designed specifically to control the 5-motor Robot Arm sold by Baycom Technologies.  It has no input facilities, but it is less expensive than combining the I/O Board with the Relay sub-Board.  If you need lots of relays and no input, this is the way to go. __ Contact: IQ Technologies

The AVR based USB Touchscreen Mouse Introduction We have been selling the PSP and Nintendo DS touchscreens for a while now and it is about time we do something cool that uses them.  A LCD touchscreen project first comes to mind, but I really wanted to do something different.  Ryan, one

The Future of Place & Route 07/02/01  EDN-Design Ideas As with all EDA sectors, the main question facing the place-and-route sector is, how do we provide enough value to ensure mass proliferation of our newest technologies among our customer-base? And, as with all other sectors, the answers are neither easy Design by J Janac

The Great Z80 Computer Project The Great Z80 Computer project was originally started way back when I was 13 or so, must have been about 1984 or thereabouts.  Like many of my projects, an article in an electronics magasine inspired the project.  What tends to happen is that I read an article, understand something of how their circuit works, in this case how to build a Z80 computer, then my imagination gets carried away with how I might design my own. __ Designed by Hans Summers

The Itsy-Bitsy USB Lamp It plugs into the USB port and is just the shot for checking motherboard switch and jumper settings.__ SiliconChip

The KD2BD Pacsat Modem The KD2BD Pacsat Modem is a low cost, high performance 1200 bps BPSK modem designed to interface between a packet radio terminal node controller (TNC) and an amateur satellite ground station, and allows full-duplex access to the 1200 baud "Pacsat" constellation of amateur satellites. __ Designed by John A. Magliacane, KD2BD

The Relay Sub Board Use nine pieces of hookup wire (or a piece of ribbon cable) to connect corresponding points on the I/O Demonstration Board to the Relay Sub Board.  Connect 12 volts DC (smoothed) to the power input points on the I/O Demonstration Board.  Solder in as many relays as you intend to use, each with its associated LED, resistor and 1N914 signal diode.   __ Contact: IQ Technologies

The USB MIDI-Mate: a MIDI Interface for PCs An up-to-date MIDI interface for PCs__ SiliconChip

The Wire Between Multiio Card & Joystick Connector Some PC multi-IO cards have a 16 pin header in the circuit board which is wired to the joystick connector (fitter to other slot place) using flatcable.  The wiring is straight one-to-one connection but, due to the different numbering scheme of the gameport connector vs the 16-way header, the pin numbers don't necessarily match (pin 16 in header is ocource lef not connected because joystick connector has only 15 pins) (Design Idea   07/03)  __ Designed by Tomi Engdahl

Thermistor Thermometer Simple thermometer made with NTC thermistor.   __ Designed by Wichit Sirichote

Thermocouple Interfaces to Serial Port 11/09/95 EDN-Design Ideas The circuit in Figure 1 acquires temperature data via an IBM PC serial port using a thermocouple-based sensor.  The sensor is a type-K(chromel-alumel]thermocouple.  When in contact, the dissimilar metals produce a potential difference that is a function of temperature.  Additional thermocouple junctions Design by Daniel Segarra, Sipex Corp  Billerica, MA

Three Wire RS232 to RS485 Converter The schematic diagram below show the circuit diagram of an RS232 to RS485 converter circuit.  The  EIA-485 standard, a.k.a TIA/EIA-485 or RS-485, is a physical layer standard defining the electrical properties of electronic drivers and receivers using balanced digital signal which is capable of handling multipoint systems.  The ANSI Telecommunications Industry Association/Electronic Industries Alliance   (TIA/EIA) is the organization who publish this standard.

Three-Input Supply Powers 3.3V Portable 04/13/95 EDN-Design Ideas The single-ended primary-inductance converter in Fig 1 accepts input voltages ranging from 3 to more than 6V and produces a regulated 3.3 V, 200-mA output.  The converter accepts an input voltage from three sourcesa 5V dc wall cu Design by Len Sherman, Maxim Integrated Products, Sunnyvale, CA

Three-State Switch Interface Uses One Microcontroller Pin 02/21/08  EDN-Design Ideas A single microcontroller I/O pin senses the state of a three-position switch Design by Kartik Joshi, Netaji Subhas Institute of Technology, New Delhi, India

TiltStick, a Motion sensing Device The TiltStick is a small acceleration sensing device in form of a USB stick.  It's using a two axis acceleration sensor to measure acceleration (caused e.g.  by motion and tilt).  The device is emulating a USB joystick and can thus be used in conjunction with any USB equipped host (e.g.  a standard PC or the Nokia N8XX family) without any special drivers.  The TiltStick is the successor of the Tilt Dongle for Palm OS. __ Designed by Till Harbaum <Till @ Harbaum.org>

Time Switch V1.0 New weekly scheduler made by 68HC908QY4 with kaypad and 16x1 line LCD! (not recommended) __ Designed by Wichit Sirichote

Tiny Server The device that converts RS485 and RS232 to the ethernet LAN has been developed.  The device was built with the Lantronix XPort embedded ethernet server and the industrial standard differential RS485 transceiver, 75176 and the single-end RS232 driver, MAX232.  The XPort module provides 10/100 ethernet port and the +3V logic UART.  The 75176 and MAX232 are +5V TTL logic __ Designed by Wichit Sirichote

TM-441 9k6 packet Modification Schematic only __ Designed by Guy Roels ON6MU

< a non-standard 2.5mm audio style jack that has four poles on the inside and two around the outer sheath.  I have been unable to find a convenient source for the connectors so will remove and replace with a cable to mate with a Digilent PmodRS232 adapter to perform 3.3V TTL to RS232 conversion during debugging __ Designed by Peter Johnson

Transaction Approach to Error Handling EDN-Design Ideas 04/28/94    You can apply the transaction-based recovery concept used in databases to any application.  Doing so helps provide more reusable and maintainable programs.  Programs contain two major paths: a forward path that does the work and a reverse path that rolls back the work when the program detects errors.  Typically, these paths are so tightly bound together that both paths are difficult to read.  Code that is difficult to read results in code that is difficult to write, debug, enhance, and reuse.    Design by Bruce A Rafnel, Hewlett-Packard Co

Transceiver to PC soundblaster interface for digital operating Modes (PSK-31, RTTY, SSTV etc) All three interfaces presented on this page employ galvanic isolation of the transceiver from PC computer.  Audio paths are separated by transformers, optocouplers serve to separate the digital paths (PTT and RTTY keying). __ Designed by Aleksander Stare

Transfer data frames over asynchronous RS-232C lines 01/15/98 EDN-Design Ideas The asynchronous RS-232C interface is a simple, low-cost option for interconnecting processor-based systems.  In many applications, you need to transfer variable-size messages.  However, the character-oriented RS-232C protocol offers no direct mechanism for transferring messages as self-contained packets.  The method described here uses an obscure feature found in most UART devices to indicate packet boundaries.  The feature is the capability to transmit and recognize the "Break" character.   Design by SK Shenoy, Naval Physical and Oceanographic Lab, Kochi, India

Translate TTY Current Loop to Rs-232 08/01/98 EDN-Design Ideas (NOTE : Multiple circuits in this file, scroll to find this one.)The circuit in Figure 1a provIdeas signal translation between a passive current-loop (TTY) interface and a duplex RS-232C port.  The current flowing in the receiver loop causes the transistor to pull down RxD; when the transistor turns off, R1 pulls up RxD.  In like manner, the current in the transmitter loop switches on for a negative TxD voltage and off for a positive voltage.   Design by Jerzy Chrzaszcz, Warsaw University, Poland

Transmitter Accurately Transfers Voltage Input 15-May-03 EDN-Design Ideas When you connect remote sensors to a central process controller, a simple, robust, and commonly used interface is the 4- to 20-mA loop.  The advantages of this current loop include the simplicity of just two twisted wires that share both power and signal, the loop's high noise immunity in harsh environments, and the de facto loop standard within the process-control industry Design by Clayton Grantham, National Semiconductor, Tucson, AZ

Tricks improve on Excel LCD initialization 04/11/02 EDN-Design Ideas A previous Design Ideas on using Excel for LCD initialization relies on the user for cutting and pasting from Excel into an editor(Reference 1].  It appears that it would take a minimum of six keystrokes or mouse strokes from one character to a new character to perform this operation.  This procedure does not allow for the addition of comments, which would be advantageous in the maintenance Design by Aubrey Kagan, Weidmüller Ltd, Markham, ON, Canada

Tricks increase utility of parallel port 09/27/01 EDN-Design Ideas In this simple application of the 68HC68 microcontroller's serial-I/O utility, the goal is to configure a simple circuit, driven by any LPT parallel-printer port, which you can use as a remote I/O for a PC.  You can independently program each I/O line as either an input or an output.  The protocol in this application is an SPI(MISO/MOSI/SCK] type, using synchronous serial communications Design by Lorenzo Tazzari, Selex SNC, Alessandria, Italy

Triple Output 3.3V 5V & 12V High Efficiency Notebook Power Supply DN78 Design Notes__ Linear Technology/Analog Devices

TSR Logs Assembler & Compiler Errors in File 04/27/95 EDN-Design Ideas If you use a PC to develop software for embedded systems, you probably still use good, old MS-DOS for most of your processing, because most compilers, assemblers, and linkers don't run under MS Windows.  If you're developing a sizable program, you probably use automated procedures such as batch files or "make" files to build and rebuild your target program.  When you use batch files or make files, capturing the PC's screen output in a disk file is more convenient than sitting around, watching everything endlessly scroll by on the screen Design by John Santic, Computer Consultant, Frederick, MD

TTL <> RS232 Conversion This small realization, based on one of the most common IC (MAX232) is designed to create a small and convenient TTL to RS232 and vice versa converter.  All you need is 4 caps, one IC

TTL UART to RS232 level converter using ST232CDR RS232 in the year 2014 ??? Yes ! As it is still the mother of all serial communicationsand we use it often, we put this information here.  As memory or clock stability is nowadays a self-evidence, we dropped that handshaking stuff.  Only RX and TX are used.  And they are used therefore, as the microprocessor would call them.  The used 6-pin header has always the same pin assignment, so they (RS232,USB,XPORT,...) are all interchangeable. __ Designed by Alexander C. Frank, aka Ajarn Changpuak

TV RGB Signal Output from a SVG Graphics Card To achieve a CCInfrared conform TV signal with50 Hz vertical interlaced refresh and15.625 kHz horizontal frequency on most SVGA cards its possible to re-program CRT Timing and generate output signals outside the normal specification range.  Then some pretty simple hardware is needed for rest of the signal conversion.     __ Designed by Steffen Köhler

Two picogate Devices for bidirectional level-shifting 11-Nov-04 EDN-Design Ideas In new mixed-voltage systems, it is often necessary to level-shift a control signal from a high level to a low level.  An open-drain device, such as the 74LVC1G07, easily performs this shift.  However, when a bidirectional signal req Design by Bob Marshall, Philips Semiconductors

Two transistor replaces IC 02/07/02  EDN-Design Ideas Linear Technology's recently introduced LTC4300 chip buffers I2C clock and data lines to and from a hot-swappable card.  This task is difficult because the IC must work bidirectionally, meaning that you can simultaneously and active Design by Jim Hagerman, Hagerman Technology, Honolulu, HI

Two Transistor replaces IC (Hagtech) I am always impressed with the way semiconductor manufacturers go out of their way to make the end designer’s job easier.  One example is the LTC4300 recently introduced by Linear Technology.   __ Designed by Jim Haggerman, Hagerman Technology LLC

Two Transistors Form Bidirectional Level Translator You often need to convert a logic signal from one power-supply voltage to another.  This conversion is a relatively simple task, unless the signal happens to be bidirectional.  Serial buses such as Access.  Bus, I2C, and SBI use bidire�Ψt into __ Designed by Jim Hagerman, Nokia Mobile Phones, San Diego, CA

Two wire 4 by 4 key keyboard interface saves power 08/17/06 EDN-Design Ideas Resistor matrix and microcontroller encode keypadYou can use a microcontroller that includes an ADC to design a two-wire-plus-ground keyboard interface.  For example, you can use a resistive voltage divider to identify a pressed key   (Reference 1).  A microcontroller's integrated ADC typically presents an input resistance on the order of hundreds of kilohms, and, for adequate accuracy, its keypad divider should comprise relatively low-value resistors of 10s of kilohms.   Design by Stefano Salvatori, University of Rome, Rome, Italy, and Gabriele Di Nucci, EngSistemi, Rome, Italy

Two-wire interface has galvanic isolation 11/11/99 EDN-Desgin IdeasUnlike the four-wire SPI, QSPI, and Microwire data-interface standards, I 2 C and SBBus buses require only two wires for data transmission, because they send and receive over the same wire.  The circuit in Figure 1 provIdeas galvanic isolation for the two-wire interface.  A small transformer and a MAX253 transformer driver   (not shown) derive an isolated 5V rail from the master-side 5V rail.    Design by Minh-Tam Nguyen