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Replacing CH340G with PL2303 module?

Discussion in 'Arduino' started by Pommie, Dec 26, 2017.

  1. Pommie

    Pommie Well-Known Member Most Helpful Member

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    If I desolder the CH340 from an UNO board (or snip pins 2 & 3) and connect an external PL2303 USB - RS232 converter, will it be recognized and will it work?

    I want to run the RS232 signals through a swivel connection - probably a jack socket and thought this may be the best way.

    Edit, just realized the DTR pin is used to reset the atmega. Guess the answer is no.

    Mike.
    UNO Schematic, UNO schematic.jpg
     
    Last edited: Dec 26, 2017
  2. ericgibbs

    ericgibbs Well-Known Member Most Helpful Member

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    hi Mike,
    Would be possible just to disconnect the TXD output on the CH420 and connect the RXD lines in parallel.?

    Eric.
    Merry Xmas & Happy New Year.
     

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  3. be80be

    be80be Well-Known Member

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    You can press the reset and use just the rx and tx it's little tricky at first but it does work.
     
  4. dave

    Dave New Member

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  5. JonSea

    JonSea Well-Known Member

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    1/8" phone plugs are available with 4 conductors, for stereo output + mic input. Does that help?
     
  6. Pommie

    Pommie Well-Known Member Most Helpful Member

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    Hi Jon,

    My original idea was to pass the USB connection through a 4 gang jack plug but thought the faster USB speed might be a problem. As a possible solution I was going to try passing the RS232 signals through the same. Unfortunately, as can be seen on the schematic in post 1, the Arduino uses DTR to reset the chip for programming.

    Burt,
    This is for a school so something that might work isn't acceptable.

    Mike.
     
  7. be80be

    be80be Well-Known Member

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    It works that's what the reset was for at one time but you can get a bootloader that only uses tx and rx not tried it tho
     
  8. be80be

    be80be Well-Known Member

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    The 328p bootloaders NEED a reset. that reset does not need to come from the serial port; a manual reset will work fine, if it's timed correctly. The older bootloaders (atmegaboot) have an approx 10 second window, so they're pretty easy to get working with a manual reset. Optiboot (as on Uno) has a 1s timeout, so it's trickier.
     

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