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CH341a Serial Mode

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  • m1ch43lzm
    replied
    Re: CH341a Serial Mode

    Hi, according to CH341A datasheet the chip supports 5v and 3.3v input, and for 5V operation, pin 9 should be connected to a capacitor (page 3 of datasheet) and should not be fed with external power

    > will the chip accept the 5v supply and will the TTL signals become 0/5v ?
    Yes to both questions

    For 3.3v operation according to datasheet 3.3v should be connected also to pin 9 and 28 (page 7 from datasheet), yet on my programmer there's no connection from pin 9 to 28 and it works fine

    My programmer looks similar to yours, except the PCB is green, and +5v next to +3.3v on the header pins

    You could lift pin 28 and connect to +5V from USB, or cut the trace (marked in red), check first continuity from pin 28 to pin 9, should be open
    Also check continuity from pin 9 to a nearby capacitor (on mine is marked with a yellow line on the attached picture)
    Attached Files
    Last edited by m1ch43lzm; 06-17-2021, 06:55 PM.

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  • mmartell
    replied
    Re: CH341a Serial Mode

    My CH341a Programmer
    Attached Files

    Leave a comment:


  • mmartell
    started a topic CH341a Serial Mode

    CH341a Serial Mode

    I'm trying to program a Metra Axxess ASCW, it's a unit that enables you to retain steering wheel controls when installing an after market stereo in your car. The newer units use a micro usb to program this one has four pins, GND RX TX +5v.

    My CH341a programmer runs natively at 3.3v. My question is if I bypass the 3.3v regulator will the chip accept the 5v supply and will the TTL signals become 0/5v ?
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