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Thread: Weird serial bug on T3.5 - stops working until interrupted again

  1. #1

    Weird serial bug on T3.5 - stops working until interrupted again

    So i've this device has been used on hundreds of computers. But this one person is having a challenge.
    The device is a teensy serial/audio hybrid. And it reads digital pin interrupt and send data. It does not do analog read and it works fine on windows 10 and a windows 7 professional. However, the celeron windows 7 home is having the problem.

    The problem is that it will be sending serial data and it just freezes. When we use arduino serial it doesn't even start showing any data until a character is sent. THen it freezes again and another character send have it doing its serial prints again.

    Any ideas?

  2. #2
    Senior Member
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    windows 7 has a known USB driver bug, posted somewhere on the forum several times

    https://www.pjrc.com/teensy/troubleshoot.html

  3. #3
    Senior Member PaulStoffregen's Avatar
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    I have Windows 7 Home Premium here on a laptop, but it's got an i7-2760QM processor, not Celron. It's a relatively clean & unused Windows 7 install, mostly just for testing Teensy hardware. Do you think I could reproduce it here with this machine?

    And just to answer the question...

    The problem is that it will be sending serial data and it just freezes. When we use arduino serial it doesn't even start showing any data until a character is sent. THen it freezes again and another character send have it doing its serial prints again.

    Any ideas?
    I have no idea why, but that sort of "freeze" kinda sounds like how xon-xoff flow control is often implemented (when stopped, most implementations allow any character to resume).

    If it's your own software, maybe try GetCommProperties and in the DCB structure inside COMMCONFIG, make sure fInX and fOutX are false. Or if you're using a higher level language with COM port abstraction, find the equivalent settings and make sure Xon/Xoff isn't active. Maybe some other software on this particular PC is setting that as the default and that setting is getting reused when you open the port?

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