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IanP

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Posts posted by IanP

  1. In my oppinion solution given by Kevin is not the right way to go..

    I would employ any microcontroller (8051, PIC) with built-in UART, so you don't need to warry about bits, bytes and timing. All is done for you within this microcontroller. If it is for example 8051, use 11059200Hz cristal quarz and you will find a lot of application nots how to set up the UART to operate at, say, 9600bps or any other rate.
    You will also need TTL - to - RS232 level converter and there are hundreds of ICs to performe this task. (Most common are MAX232 or 202 - doesn'i need to be MAX, any with the number 202 or 232 will do).
    So you connect encoder output (assuming you have 0-5V level) to INT0 of the CPU (if you have encoder with 2 waves you will connect the other wave to any available input pins and with 2-waves shifted by 90deg you will be able to read not only distance but direction too).
    And that is your hardware!!!
    Now comes the software.
    Ask yourself in what format you would like to send data to PC:
    - raw indication that a pulse just occured ( a byte in HEX or ASCII)
    - calculated distance in from of a string 000.0 ..?

    But from this point you will not manipulate with hardare any more..
    If you are intereste I can post you some diagrams of working circuits..

  2. There are 2 ways of doing this:

    1. You can buy a PCI, ..., (depending on your computer hardware) A/D card with, say 16 analog inputs and 16 Digital I/Os.
    Cards usually come with drivers for LabView or any other data acquisition software and as software developer you will be able to get data from Thermocouples, control relays etc.
    Main disadvantage: cost.

    2. You can bild a microcontroller based interface card (8051 family, PICs,....) and fit this card with A/D and DI/O ICs.
    You will have to write a piece of software for this microcontroller and you will be using the RS-232 serial port for communication.
    The most effective here is so called command-response protocol: the PC sends command to microcontroller, command is executed and microcontroller sends back response with data from ADCs and/or confirmation of the stage of the RLYs.
    In this approach you are master of the system and you are unlimited with resources as you can expand your DI/Os by adding another IC with inputs/outputs (such as for example 82C55 : 24 digital I/Os) etc.

  3. There are hundreds of IC available on the market to write text on live video signal or to generate background and superimpose text on this background.
    Most of these IC are used in TV sets to display channel number etc and in handycams (time & date, counter etc.)
    Go to Google and type for example STV5730.. This one, I think, was described in 1999 in Elector Electronics, or was it Silico Chip, I don't remember..
    Another example may be uPD6145. An article on this one was published in Electronics World some years ago.

  4. Hi Ante,

    I have 96 low voltage lights in my house and they are fed from 240/12V transformers and for most of them I fitted light dimmers.
    These devices are using triacs (not scrs). Obviously, as they are phase control regulators, the shape of the "sine" wave is not sine any more but that doesn't matter.
    Transformers? Who cares, they are as cold as ambient temperature...+ a little bit...

  5. If you are familiar with 8051 family you can go to Philips Semiconductors and find application note AN434.
    There you will find complete description on how to connect a PC keyboard to I2C bus and instead of using I2C routines (wich are pretty complicated) you may use standard assembler commands for sending bytes out and in (most om 8051 will have built-in UART).

    This is not keyturn solution but is pretty close to what you would like to do...

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