Doubt regarding serial communication project

Discussion in 'The Projects Forum' started by deepakj2004, May 31, 2010.

  1. deepakj2004

    Thread Starter New Member

    May 31, 2010
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    Hi guys,

    I have a question regarding my digital design project which basically involves
    converting an analog value to digital, transmit it serially over a 6 foot interface and then at the receiver end, convert it back to analog.I cant use any microcontrollers;I'm using an AD7574 for converting the analog value to 8 bit digital value,then convert this to serial data using 74LS 165 parallel to serial converter. At the receiver I'll do just the opposite using 74LS 164 and DAC0800 to get back the analog value.
    Now how can I send this serial data through a wire? I thought I could use RS-232 protocol;but I'm not sure how it could be done. Do I need to use a MAX 232 chip or something?

    Please help me out here:confused:
     
  2. mik3

    Senior Member

    Feb 4, 2008
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    Yes, it would be easier if you use a MAX232 chip.
     
  3. deepakj2004

    Thread Starter New Member

    May 31, 2010
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    So I just have to connect a MAX232 to the 74LS165 output?Doesnt it need any additional devices?

    Thanks in advance.
     
  4. t06afre

    AAC Fanatic!

    May 11, 2009
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    In serial communication you have something called start and stop bit. To transfer 8 bit you need at least 1 start and 1 stop bit. Have you considered that in your circuit?
     
  5. deepakj2004

    Thread Starter New Member

    May 31, 2010
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    Oh thanks t06afre; I forgot that entirely.Isn't that done by a UART?Is there any specific IC which I can use for this purpose?
     
  6. t06afre

    AAC Fanatic!

    May 11, 2009
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    Can you give us more information. Like what kind of unit is sending the 8 bit to the DAC0800 application. Somehow I think you are on the wrong track here.
     
  7. deepakj2004

    Thread Starter New Member

    May 31, 2010
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    I havent decided anything on the communication part yet.All I have is an ADC which samples analog value at 8khz(AD7574) and a parallel to serial converter(74LS 165) which generates serial data at 64kbps at the transmit side.The receiver side will have a serial to parallel converter(74LS 164) and the DAC chip(DAC0800). Data transfer is only unidirectional.Now somehow I need to connect these two sides using a 6 foot wire interface.How can I insert start/stop bits in to this 64kbps data so that I could send it across the RS 232 interface?
     
  8. BMorse

    Senior Member

    Sep 26, 2009
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    If it is only 6 feet distance, I would just connect the serial output of the transmitting IC directly to the receiving IC's serial input.... have you tried that?

    B. Morse
     
  9. deepakj2004

    Thread Starter New Member

    May 31, 2010
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    Or can I use the SPI bus for this purpose?Is there any chip which can accept parallel data and send it across the spi bus?I'm sorry if it sounds stupid;I'm just a newbie.
     
  10. deepakj2004

    Thread Starter New Member

    May 31, 2010
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    @BMorse
    So it doesnt need to be send via RS-232 interface?Just connect 74LS 165(parallel to serial converter IC) to a 74LS 164(serial to parallel converter IC)?Never thought it could be that simple.
     
  11. BMorse

    Senior Member

    Sep 26, 2009
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    Should work, if that is all you are doing is sending the serial data from one parallel to serial IC to a serial to parallel IC....you will have to try it first and see if the length of the cable might be an issue, if it is, you can use a MAX232 or similar IC to "boost" your transmission, but no need for the 1 stop bit, start bit stuff, since you are not actually using the RS232 protocol to talk to an actual USART....

    B. Morse
     
  12. t06afre

    AAC Fanatic!

    May 11, 2009
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    It will also be important for the solution. And please answer this time. What kind of unit do you use to send data to the ADC unit. Like is it a PC?
     
  13. BMorse

    Senior Member

    Sep 26, 2009
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    The OP already stated where he is getting the data from:

    No PC's are involved here....

    B. Morse
     
  14. deepakj2004

    Thread Starter New Member

    May 31, 2010
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    Thanks B. Morse;I'll try connecting both the ICs together and see if it works.

    @t06afre

    I'm just connecting 1 kHz sine wave at the ADC input to get the analog value.There is no PC involved here.The objective of the project is just to convert an analog signal to digital,transmit it across a medium and then convert it back to the analog signal.
     
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