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Inverting RS232 Signal?

Discussion in 'General Electronics Discussion' started by jeff77789, Mar 22, 2013.

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  1. jeff77789

    jeff77789

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    Feb 23, 2013
    I have a Maxbotix MB1030 ultrasonic sensor, in which it gives out a "Tx" digital signal which is:

    When the *BW is open or held low, the TX output delivers
    asynchronous serial with an RS232 format, except voltages are 0-Vcc.
    The output is an ASCII capital “R”, followed by three ASCII character
    digits representing the range in inches up to a maximum of 255,
    followed by a carriage return (ASCII 13). The baud rate is 9600, 8
    bits, no parity, with one stop bit. Although the voltage of 0-Vcc is
    outside the RS232 standard, most RS232 devices have sufficient
    margin to read 0-Vcc serial data. If standard voltage level RS232 is
    desired, invert, and connect an RS232 converter such as a MAX232.
    When BW pin is held high the TX output sends a single pulse, suitable
    for low noise chaining. (no serial data).


    it mentions that the signal is inverted and you can use something such as a MAX232 to invert the signal...first of all i don't even know where to get one of those converters
    if i wanted my arduino to read this signal, what can i do to invert the RS232 signal?
     
  2. BobK

    BobK

    7,682
    1,688
    Jan 5, 2010
    I am non sure about Arduino (AVR), but on PIC you can set up the serial I/O peripheral for inverted input. Read the datasheet, it might be able to handle it as is.

    Bob
     
  3. Harald Kapp

    Harald Kapp Moderator Moderator

    11,533
    2,656
    Nov 17, 2011
    To connect the signal directly to a microcontroller do not use an RS232 converter unless the contrroller board has a true RS232 interface. I guess s the arduino has a TTL level serial interface (not sure about that, read the arduino`s documentation). If so, the RS232 level will damage the arduino.
    As for inverting the signal, a simple transistor inverter (Google) wil suffice at the typical speed of a UART port.
     
  4. jeff77789

    jeff77789

    17
    0
    Feb 23, 2013
    so basically it is an inverted ttl signal?
     
  5. Harald Kapp

    Harald Kapp Moderator Moderator

    11,533
    2,656
    Nov 17, 2011
    Most probably you don't need an inverter at all. If they state that a MAX232 is suitable, then the TTL signal should already have the correct polarity.
     
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