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Separating the prop from the PST — Parallax Forums

Separating the prop from the PST

ElkinElkin Posts: 58
edited 2011-05-05 00:47 in Propeller 1
Does anyone know how I can disable the PST after I start my method, unplug the prop from my computer where it now runs alone. After some time I can come back and reconnect the prop to the computer and restart the PST to check the progress of the program without stopping the current program that is running?

I am able to disable and enable the PST without any problems but I can not unplug the serial cable from the port and reconnect it without terminating the program.

Comments

  • StefanL38StefanL38 Posts: 2,292
    edited 2011-05-04 09:08
    The USB-programming interface that is connected to pins 30,31 also is connected to the reset-input.
    If you make the reset-input switchable you can disconnect the reset-input and then connect again.

    Now it depends on the board you are using how easy or difficult it is to make the reset-input switchable.

    Another possability is to use another two pins for a serial connection or if you just want the propeller to send
    another single pin used as TX-line. Therefore you need an adapter-IC like the MAX3222 which converts from propeller 0/3.3V TTL to V24 +-12V

    It is NOT possible to directly connect a standard comport or an USB-to-RS232 adapter to the propeller-chip.

    to give further advice please write us which board you are using.

    best regards

    Stefan
  • ElkinElkin Posts: 58
    edited 2011-05-04 09:14
    I would prefer to make the reset input switchable if that is possible. the board that I am suing is the protoboard USB with the P8X32A-Q44. It isnt really that easy to use 2 other pins for this because all of them are basically filled.
  • jazzedjazzed Posts: 11,803
    edited 2011-05-04 10:41
    Guess you'll have to do surgery with this problem. Several of us who make boards add a jumper for the problem you are facing. We have mentioned this to Parallax for their new boards.

    I have not tried the solution below, but "it should just work" ... famous last words. Use at your own risk - YMMV. If you do this rework, you will need to jumper the two pins for programming the propeller chip. Once it is programmed, you can remove the jumper and remove or plug in your USB cable later without affecting reset on the the Propeller chip.

    A picture is attached that shows where you could do some cut/jumps to add a reset-enable header. Red is cut; green is jump. If you're careful and cut the trace in the middle, you can use the copper side of the rolled back traces to make the jumps instead of adding wires. Then you can add a jumper.

    Good luck.
    PropProtoUSB-ResetJumper.png
    690 x 508 - 209K
  • ElkinElkin Posts: 58
    edited 2011-05-04 10:50
    Haha, alright. I will have to take a better look at this before I try it. Is there another thread or something that parallax has published that better describes what you are talking about? I actually do think this would work but I would just like to have a better idea what I need to do before I start. Thanks for the tip!
  • jazzedjazzed Posts: 11,803
    edited 2011-05-04 11:19
    Elkin wrote: »
    Haha, alright. I will have to take a better look at this before I try it. Is there another thread or something that parallax has published that better describes what you are talking about? I actually do think this would work but I would just like to have a better idea what I need to do before I start. Thanks for the tip!
    You'll have to search I guess. I've never seen anyone offer a solution to this problem before.
    Sometimes offering help is satisfying, other times it is not. Good luck.
  • WBA ConsultingWBA Consulting Posts: 2,935
    edited 2011-05-04 11:42
    Nice idea jazzed! I have another proto board that is just beginning to be "hacked" for a project, so I will add this to my list just to try it out.
  • davidsaundersdavidsaunders Posts: 1,559
    edited 2011-05-04 12:00
    If you have the space on the board, and a Prop Plug, you could as easily add a 4 pin header wired directly to P30, P31, Vss, and /RES, with a jumper between the header and /RES. This kind of thing is why I do not use the USB version of the board. For the wiring see the diagram in the Propeller Data Sheet.
  • ElkinElkin Posts: 58
    edited 2011-05-05 00:47
    Jazzed, That was a pretty neat trick. I managed to run some wires out to a switch for easier accessibility. Thanks for the tip, it is working great!
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