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Only works when connected to computer? — Parallax Forums

Only works when connected to computer?

HMSTLHMSTL Posts: 16
edited 2013-01-16 22:36 in Propeller 1
I'm having an issue where my proto board is only working when the USB is connected to a computer. When it is unplugged the program is not executing properly and exhibits random behavior.

Comments

  • RaymanRayman Posts: 15,496
    edited 2013-01-12 17:43
    That sounds like it might be the FTDI reset bug...

    If you are using serial comms, such as "fullduplexserial", try turning that off...
  • SRLMSRLM Posts: 5,045
    edited 2013-01-12 19:12
    I agree, it sounds like the FTDI reset bug: http://forums.parallax.com/showthread.php/116711-Can-Parallax-do-something-about-the-FTDI-reset-bug
  • HMSTLHMSTL Posts: 16
    edited 2013-01-16 18:56
    Thanks for the replies. After restarting my computer the problem seems to have gone away. Good thing since I have no idea how to go about turning off whatever you're talking about.
  • SRLMSRLM Posts: 5,045
    edited 2013-01-16 22:36
    The problem is that, for serial communications, the serial line idles in the high voltage state. In the old FTDI circuits the high idle provided enough power to the FTDI chip to briefly start it up, and it would promptly reset the Propeller. This created a cycle.

    The solution is to have a better circuit. The compromise is to not start the serial object on pins 30 and 31 unless you are connected to a computer.
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