Rs232

Discussion in 'General Electronics Chat' started by Terp, Jun 12, 2008.

  1. Terp

    Thread Starter Active Member

    Jun 6, 2008
    32
    1
    Hi !!!

    I am working on making a remote-controlled bird automated. This being my first robotics project, has involved substantial amount of research, and I am still a bit unclear about communication between laptop and the PIC.
    :confused::confused::confused:

    I want to communicate with my PIC via an RS232 connection. My question is, what exactly does an RS232 look like? I know that it deals with DB-9 cable with 9 holes. I am wondering, after the male-female connection is made with the computer, what is on the other end of the RS232 that is to be connected to my robot?

    Thanks
     
  2. beenthere

    Retired Moderator

    Apr 20, 2004
    15,815
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  3. Terp

    Thread Starter Active Member

    Jun 6, 2008
    32
    1
    Thank you for the site!!!

    Yes, indeed. I have a Laser 6 FM radio control system. What I want to do, is replace the analog potentiometers currently inside the transmitter, connected to the sticks, with digital pots. Then, I will write a program that would vary the resistance in the pot. With varying resistance, the transmitter transmits signals, which are captured by the receiver on the bird.

    Back to RS232: The site was pretty helpful, but still I have unanswered question. Okay, on my computer is the female end of the DB-9. Lets say we connect a DB-9 male end to it. I am not sure, what is on the other end of that male end? Is this what the RS232 link that is between the laptop and the PIC look like, assuming that the DB-9 in this picture were a male, instead of a female.

    [​IMG]
     
  4. beenthere

    Retired Moderator

    Apr 20, 2004
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    You will need a microprocessor at the receive end of the RS-232 link to take in the commands and pass then on to the DPOT's. Chances are good that the DPOT's will use a different protocol to take commands from the microprocessor. You will need to check carefully to see that a control pot may be replaced by a DPOT. DPOT's are much more current limited than analog pots.
     
  5. cumesoftware

    Senior Member

    Apr 27, 2007
    1,330
    10
    You can use the MAX232 from Maxim of from TI. The MAX232 works with 5V and has an integrated charge pump so it can send signals with 12V used in a regular RS232 communication. It also accepts 12V signals and converts them to 5V signals. This makes the chip great for single supply applications.

    As for the communication standard, it seems that you have to program your micro-controller to do just that. The MAX232 is a mere interface. You can use asynchronous RS232, since it only requires the use of two signals. So you use your TX (2) and RX (3) pins to send and receive data.

    Admit that your device is a periferical device (DCE) like a modem. Thus you should use a female DB-9 socket soldered to your PCB, and the plug (cord) on the side of your device should be therefore a male. It is a matter of conventions.

    This site has very useful tips (first hit on Google):
    http://www.camiresearch.com/Data_Com_Basics/RS232_standard.html
     
    Last edited: Jun 12, 2008
  6. Terp

    Thread Starter Active Member

    Jun 6, 2008
    32
    1
    I have a built-in RS232 port (w/ MAX232) on my circuit board.

    Now I am all clear with RS232 interfacing. Its just a means of communication between the two -- like a telephone.

    Thanks much!!
     
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