Serial Communication with PIC16F877A


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  1. #1
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    Make sure the cable is not for a modem. Pin 2 on one end goes to Pin 2 on the other, the same for pin 3.

    Test PC serial port by jumping PINs 2 and 3 with a 10K and use a terminal to see if you get an echo.
    Dave
    Always wear safety glasses while programming.

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    Question reply...

    Quote Originally Posted by mackrackit View Post
    Make sure the cable is not for a modem. Pin 2 on one end goes to Pin 2 on the other, the same for pin 3.

    Test PC serial port by jumping PINs 2 and 3 with a 10K and use a terminal to see if you get an echo.
    I tested my serial port and sent 5 succesfully in the loopback... what else can i try?

    Morris Beasley
    Manufacturing Test Technician
    B.S. Industrial Technology (2007)

    For more information on our robotics, please visit:
    http://www.ish-electronics.webs.com

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    Post schematic...

    I am attaching a bitmap of my schematic for my ICD and ICP. I am using the ICD for the serial communication.
    Attached Images Attached Images  

    Morris Beasley
    Manufacturing Test Technician
    B.S. Industrial Technology (2007)

    For more information on our robotics, please visit:
    http://www.ish-electronics.webs.com

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    Quote Originally Posted by mackrackit View Post
    Make sure the cable is not for a modem. Pin 2 on one end goes to Pin 2 on the other, the same for pin 3.
    Did you test as Mackrackit suggested above? Many serial appearing cables are actually laplink cables, or nul modem cables and the Tx and Rx pins are crossed so two computers can be linked directly.
    If you do not believe in MAGIC, Consider how currency has value simply by printing it, and is then traded for real assets.
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    Quote Originally Posted by Joe S. View Post
    Did you test as Mackrackit suggested above? Many serial appearing cables are actually laplink cables, or nul modem cables and the Tx and Rx pins are crossed so two computers can be linked directly.
    Yes I tested it... I successfully sent a message through my cable and echoed it back by shorting pin 2 to pin 3.... any other ideas?

    Added:

    Is there anyway to tell if my cable is crossed as you suggest?... I know I got the echo by shorting pin 2 to pin 3 but I would still get the echo if the pins were crossed...

    Resolved:

    Thank you guys for your help. After testing my cable for continuity I realized that it is crossed. Going to get a new cable and hopefully that fixes the problem.
    Last edited by mcbeasleyjr; - 27th May 2009 at 21:51. Reason: another question...

    Morris Beasley
    Manufacturing Test Technician
    B.S. Industrial Technology (2007)

    For more information on our robotics, please visit:
    http://www.ish-electronics.webs.com

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    Just reverse the connection at the device end, swap pins 2 and 3.
    Or cut the cable...
    Dave
    Always wear safety glasses while programming.

  7. #7
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    Quote Originally Posted by mackrackit View Post
    Just reverse the connection at the device end, swap pins 2 and 3.
    Or cut the cable...
    Or if you have a null modem adapter use it to swap back . . .
    If you do not believe in MAGIC, Consider how currency has value simply by printing it, and is then traded for real assets.
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    Gold is the money of kings, silver is the money of gentlemen, barter is the money of peasants - but debt is the money of slaves
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    There simply is no "Happy Spam" If you do it you will disappear from this forum.

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