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<help> Serial RS232 doesn't work — Parallax Forums

<help> Serial RS232 doesn't work

yuana2004yuana2004 Posts: 2
edited 2010-01-22 04:52 in Propeller 1
Hello, I am a newbie with parallax propeller P8X32A.

I have build serial to propeller circuit from this link http://www.parallax.com/DiagramsSchematicsandImages/tabid/254/Default.aspx ,

After finish, I try to connect to computer via serial with propeller tool v 1.2.6, but the computer
doesn't find any propeller chip.

Anybody know how to solve it??

I have checked all of my connection, and I am sure there is no mistake.

Are there any driver that I should install before use serial connection?

thanks...
confused.gif

Comments

  • E-HeadE-Head Posts: 13
    edited 2010-01-19 11:02
    Well, I assume that you use a breadbord where you put the propeller. Have you checked that the propeller chip is pushed down until the chip is contact with the breadbord. I didn't push the chip enough so the chip's pins didn't take contact with the breadboard. When I now look my chip mounting, there is now empty space between the chip and breadboard.

    [noparse]:)[/noparse]
  • Mike GreenMike Green Posts: 23,101
    edited 2010-01-19 14:49
    In order to be able to "find" the Propeller chip:

    1) The Propeller has to have power. The crystal, if any, doesn't have to work for downloading and the EEPROM doesn't have to be there unless you try to download to EEPROM.

    2) There has to be a functioning serial connection including the DTR control line.

    3) If you're using USB, the USB to Serial Adapter has to properly implement the DTR signal line. Many Adapters do not do this.

    4) If you're using USB, the proper USB driver has to be installed. The default Windows driver doesn't work for downloading (or identifying a Propeller).
  • yuana2004yuana2004 Posts: 2
    edited 2010-01-20 11:43
    I have checked the power and it give 3.3V to Propeller.
    I don't know that my crystal work or not.
    How to check it?

    I use serial connection,and it has DTR control line.
    When I connect my propeller circuit to PC, I check the voltage at P11(RESn) to the ground and it's about 2.2V.
    I check P31 and its about 3.3V.
    P30 give about 1.2V.

    I don't know where the problem is.

    I suspect my transistor, but I don't know how to check it.
    I also don't know that my propeller is fine or not...??
  • Mike GreenMike Green Posts: 23,101
    edited 2010-01-20 15:29
    The circuit that was posted does work and the Propeller normally works. There must be something wrong with how you've connected it. The only thing you can do is to recheck all your wiring.

    Crystals usually work unless they are dropped many feet onto a hard surface or stepped on or smashed with a hammer. Like I said, the crystal doesn't have to work for downloading or the identification process.

    Transistors usually work unless you've damaged them by putting too much current through them. The easiest way to check a transistor is to try another one in its place.

    The only way to check a Propeller is to put it into a known good circuit like the one you are trying to get to work.

    There have been many people who have had problems with their software "finding" either a Propeller or a Stamp and have claimed that they've checked their wiring carefully. In almost all cases, they have eventually found a power problem or a wiring problem, sometimes a problem with their serial cable.

    Post Edited (Mike Green) : 1/20/2010 3:34:16 PM GMT
  • AribaAriba Posts: 2,690
    edited 2010-01-22 04:52
    When you say: P11 = RESn, then you mean Pin 11 of the DIP version, and not PortPin 11 (PA11).
    So when you say P30, P31 do you mean Pin 30 and 31 of the DIP (the Oscillator pins) or the Port-pins 30,31 at Pins 39 and 40 of the DIP?
    The Serial Interface must be connected at Port-pins 30 and 31 and not to the XO, XI Pins!

    Have you tied the BOEn Pin to Ground?

    Andy
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