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How to prevent FTDI from resetting the propeller? — Parallax Forums

How to prevent FTDI from resetting the propeller?

william chanwilliam chan Posts: 1,326
edited 2010-07-26 06:30 in Propeller 1
Hi,

I am using the Propeller Proto Board USB on a Boe Bot.
I started a FullDuplexSerial object to send back debugging strings to the PC via the onboard FTDI chip.
Everything works well.

But when I disconnect the USB cable, some debugging strings that are still being sent to the FTDI chip will cause the FTDI chip to reset the propeller.
Is there a way around this?

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www.fd.com.my
www.mercedes.com.my

Comments

  • KyeKye Posts: 2,200
    edited 2010-07-25 14:35
    Just disable the Serial Driver. More exactly make pin 30 an input or low.

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    Nyamekye,
  • Phil Pilgrim (PhiPi)Phil Pilgrim (PhiPi) Posts: 23,514
    edited 2010-07-25 16:24
    William,

    Until Parallax fixes the problem (see here) by adding a buffer in their next board rev, you can work around the issue by adding 4.7K pull-ups to A30 and A31.

    -Phil
  • william chanwilliam chan Posts: 1,326
    edited 2010-07-26 00:42
    Thanks Kye and Phil for the link.
    Now I understand the problem better.
    Looks like I will be using the VGA for debugging now.

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    www.fd.com.my
    www.mercedes.com.my
  • Greg PGreg P Posts: 58
    edited 2010-07-26 03:46
    I ran across this problem (once again) on a recent project. This project did not require
    a PC serial connection, relying instead on a keyboard and tv object for operator communication.
    I just tweeked SerialMirror so that a single flag register would either enable or disable
    the serial cog and all its method calls. This allowed me to quickly remove the 'rebooting'
    problem in the final design without the necessity of deleting the many serial object method
    calls scattered throughout so many objects (created for debugging purposes only).

    See this recent post for project details:

    http://forums.parallax.com/showthread.php?p=924698
  • DavidMDavidM Posts: 630
    edited 2010-07-26 06:30
    Hi William Chan,

    I use the following circuit to solve this issue..

    You need somewhere in your code a facility to turn on or off the RESET DISABLE LINE, this could be a mechanical switch ( during development ) but for end product use,
    you would have some kind of USER ENABLE input ( via a menu ??) to allow UPDATING OF FIRMWARE, but normal USB transmissions and Cable disconnections would not be a problem.

    regards


    Dave M
    pdf
    pdf
    USB REV-H.pdf
    21K
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