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QS Rev.A programming through header — Parallax Forums

QS Rev.A programming through header

PFloyd36069PFloyd36069 Posts: 135
in Propeller 1
Hello All,

Is there any workaround to be able to program the Rev. A quickstart through the 40 pin header? I am trying to use my wifi module for wireless programming but it doesn't work as it should. I soldered a lead from the DTR pin on the module and hooked it to the RESn pin on the quickstart and that portion seems to be working fine. I believe the problem lies with the QS board pulling the RX pin low.

Thanks,
Bryan

Comments

  • PFloyd36069PFloyd36069 Posts: 135
    Anyone? :cool:
  • davidsaundersdavidsaunders Posts: 1,559
    It should be possible, let me look at the schematics, will get back to you.
  • davidsaundersdavidsaunders Posts: 1,559
    Header pins 33 and 35 go to P30 and P31 on the prop, thus giving the RX/TX for the programmer, and reset is exported through header pin 37, all this on the Rev A board.

    There is nothing that should not be anything on the board that would hold it low like that, I just took a good look at both the Rev A schematics, and the PCB layers for the Rev A, nothing on the board should be holding either the TX or RX low. As to the RESn (reset) that I am not sure of, as I can not find anything connected other than the header, where there should be a connection for programming through USB.
  • davidsaundersdavidsaunders Posts: 1,559
    Ok I found where it is connected to the FTDI chip, through a transistor. Unless programming through USB the Reset line should not be pulled down either.

    So I can not find anything in the design to cause an issue. If you wire a normal prop plug into the header what results do you get when attempting to program the on board prop through the prop plug?
  • AribaAriba Posts: 2,682
    The Tristate buffer U4 drives the RX pin if you have the USB header connected to a 5V source.
    If you power the Quickstart over he VIN pin with 5V and leave the USB unconnected U4 may be tristated (but not for sure because the Vcc of U4 is missing then).

    Andy
  • PFloyd36069PFloyd36069 Posts: 135
    Thanks for the input guys! I had also wondered about the U4 buffer causing issues when left unpowered. I've tried with the USB powered up, I've also tried with a 10k pullup on the props RX like and still no go! I don't have a prop plug unfortunately :( maybe when I get a chance, I'll try with a different quickstart and see what happens!
  • PFloyd36069PFloyd36069 Posts: 135
    I just tried this on another quickstart and got the same results. I've attached a screenshot of my logic analyzer when I plugged in the usb. Both data lines and the reset line are sitting low until it powers up and then they are pulled up. Maybe it just wont work with a Rev. A board!
    screenshot.png
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