Quickstart Board reboots when PC GUI program starts and stops

kvanepps

I am currently using the USB port on the Quickstart board to provide a serial communication channel to a GUI program written with JAVA. It seems that when I start my GUI program and when I stop my GUI program the Quickstart board will go into a reset condition and the Quickstart restarts my program. When I start the GUI program, the Quickstart board will reboot, then my GUI works fine with communicating to Quickstart board. Then when I exit my program, I am closing my serial port and the Quickstart reboots again. Is this due to the connecting and disconnecting of the serial port in my GUI program? I thought I saw the same problem with the Quickstart board on the discussion board but I have not found it.

On the PC, I connected to another serial port with a laptop running hyperterminal and I do not see any characters being sent when I start and stop the program. The serial data sent by my GUI is correct and when I disconnect, I don't see any problems.

If this is a simple question, I apoligize ahead of time. I have been playing with the quickstart board for a few weeks.

Thanks
Ken

tdlivings

The serial signal DTR is what is messing you up.
The Prop boards use DTR to reset the chip.
When I wrote a GUI using Delphi I had to tell the Async Lib I used to
not assert DTR (Data Terminal Ready) when the GUI ran .
The Async Lib had an option to not wiggle DTR.

Tom

pedward

The PDT appears to search for a Prop on startup, at least that is what I suspect. Though the simplest answer is tdlivings.

kvanepps

Thanks guys for the quick reply. . I will look at disabling the DTR.

Thanks
Ken

Toby Seckshund

I usually stick in a jumper from the serial interface to the reset pin so that this can be definately stopped (if the BOE pin isn't decked then a pull up resistor will be required on the reset pin)

Rayman

I think I had trouble with that too... I don't remember if I came up with a good solution.
But, I think you can just disconnect your usb cable before closing the comm port...

MagIO2

Yes, for sure this helps, because the quickstart is completely out of power then .... But for sure no restart ;o)

Rayman

True. I guess that's a bit of a problem...

tdlivings

It is not a case of disabling the DTR serial signal in your cable or on your prop development board.
I am saying in your code written and running on your PC, in that code do not play with DTR.

I have a Delphi GUI which uses propellent.dll to download the code to the propeller before running the GUI.
Propellent.dll I am sure wiggles DTR but my Async serial code in the Delphi code does nothing with DTR
because I disable it's use.

Tom

kvanepps

Well, I can see that my program is causing the DTR pin to go from high to low. I looked at it with a scope. When I stop my program (GUI written in Java), it goes back to high. I am using a JAVA API called RXTX to provide my serial interface. I tried setting the DTR to be always high and when that didn't work, I set it to be always low. Still the same thing happens which reboots the Quickstart board. I dug a little more into the RXTX Serial API and discovered there may be a bug with controlling the DTR. Not good when using it with the Propeller. I also looked at the schematic of the Propeller and saw that there is a cap (C9) between U3 pin2 of the USB/Serial chip and a transistor (Q1) which drives the reset pin low. It seems that with this circuit design the Quickstart will reboot when any change on the DTR occurs which will cause the chip to reset. If U3 pin 2 of the DTR goes from high to low or low to high, the transistor (Q1) will turn on and reset the processor. If there was enough room, the trace could be cut and a jumper put in series with the between U3 pin 2 and C9. Another idea would be just to ground the base of the transistor so that it will never turn on.....

Thanks for all the feedback

Ken

obrienm

Hi,
The standard javax.comm library originally developed for linux but extended for win32 works fine for me, no resets. The library will not work on a 64 bit JVM but I am able to control multiple quickstart boards simultaneously from a single java process after first reloading them all using propellent in an Ant script.

see http://javahardware.blogspot.com/2010/11/led-display-board-driven-by-javaxcomm.html
and the original posts
http://forums.parallax.com/showthread.php?119851-Writting-propeller-data-to-a-file-on-my-PC&p=879906&viewfull=1#post879906
http://forums.parallax.com/showthread.php?109333-HowTo-Single-host-computer-and-multiple-propeller-serial-comm-and-programming&p=775612&viewfull=1#post775612
http://forums.parallax.com/showthread.php?137636-Quickstart-Board-reboots-when-PC-GUI-program-starts-and-stops&p=1071154&viewfull=1#post1071154
http://forums.parallax.com/showthread.php?132944-Java-comm-and-basic-stamp

thank you
/michael

Phil Pilgrim (PhiPi)

This is a persistent issue with Perl PC host programs, using the standard serial interface module that diddles with DTR, no matter what you tell it to do. If anyone has a work-around for that problem, I'd be very grateful if he'd share it.

Thanks,
-Phil