Intermittent usb to serial connection

SteveWoodrough

I'm having trouble getting my programs to reliably down load to the STAMP.· This has been going on for some time and I've confirmed the power supply is OK, the USB cables OK·as well as continuity from the serial port to the chip pins except for pin 4, DTR, since it goes through a cap..
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I have a tested program that takes up ~ 90% of a BS2 rev G STAMP.·
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If I plug in the USB to serial converter the PC recognizes the device just fine.·
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When I·attach the converter to the STAMP·it takes between 4 and 10 attempts to get the program to load.· Sometimes it stops at 0%, 1%, 6%, ~85% and on rare occasion it loads completely.
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Once the download gets going it is stable.· When a program does start to load, I can wiggle and jiggle the USB / serial connection and the BOT during the 7 plus second download with NO impact.···
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On the other hand I can have the whole BOE BOT sitting on the bench, plugged in and ready to download.· Without touching the BOT or the cables, it can take 4 to 10 attempts before the program will load.· Sometimes it takes, mostly it fails.
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Any·ideas on what the problem could be?
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Thanks
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Steve
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Mike Green

What USB to serial converter are you using?

Is your PC doing a background upgrade of Windows?

The behavior you describe is something I experienced sometimes on a relatively slow PC running Windows 98SE and sometimes Windows XP when Windows was running Windows Update in the background. The PC was slow enough that the extra background processing would slow down the download to the Stamp enough that it would sometimes fail due to a timeout.

Other than that, you might have an intermittent failure somewhere like in the USB to Serial Adapter, the Stamp board, or the Stamp itself. None of these are likely, but what you describe is not normal behavior. I've not had the timeout problem since I upgraded my PC (an Intel Mac actually ... running Windows XP Home), even with Windows Update running in the background.

SteveWoodrough

Well Mike, I think you are on to something, but I’d like to know if there is any way I can make the connection more reliable and why I don’t have the same trouble with programming my propeller chips (jinx!).·
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After reading your post I decided to install the STAMP software on my desk top and compare program loading performance against the laptop I use for my hobby projects.· Before deciding to do so I was convinced that the desk top would perform just as unreliably as the laptop.· I was pretty sure that somehow my serial adapter had somehow gone bad.·
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Below is the data on the equipment I’m using:
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For the STAMP I'm using the Parallax USB to Serial (RS-232) Adapter.·
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My office desk top is a dual core 5200 w/ 2.75 GB RAM @ 2.71GHz running XP PRO SP 3.· This PC has a 100% effective programming rate for the STAMP.· I have not tried to use this machine to program a Propeller.·
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My laptop for robot use is an IBM T40 1300MHz with 512 MB RAM at 274MHz running XP PRO SP3.· For the test the laptop only ran the latest STAMP editor with no other programs (IE, word, etc.) running in the background. This laptop only has 2 USB ports and I’m in the habit of using a 4 port USB hub w/o the power connection.· This MIGHT be the root of the issue.· The USB hub is plugged into a USB port on the laptop and the STAMP cable and a wireless mouse are typically plugged into the USB hub.·
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For the entire test the same, BS2 program, editor, cable, serial converter and BS2 STAMP are used.
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Using the laptop with both the STAMP and wireless mouse plugged into the USB hub proved impossible, 0 successes in over 40 attempts. ··Sometimes I’d get 0% downloaded up to 69% downloaded before getting the error message.· The same setup on the desk top had a 100% success rate.
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Using the laptop with the wire less mouse plugged directly into the built in USB port and only the STAMP plugged into the USB hub had a 40% success rate.· The same setup on the desk top had a 100% success rate.·
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Using the laptop built in USB port for the STAMP improved the success rate to 50% ·
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Clearly I’m better off programming the STAMP through the laptops built in USB port(s) and NOT using the USB hub. What I originally thought was a hardware problem (loose connection) appears more an more like a software issue with the adapter driver.
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Why is the STAMP programming so unreliable?
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Can I slow down or speed up the COM rate to improve reliability?
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Why do I not have the same issue with the Prop?
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Thank You
Steve

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Recent Project Videos:

http://www.youtube.com/watch?v=jI79Xsm_Kyk&feature=channel_page

Cool Cars:
http://www.youtube.com/watch?v=SLnPhYKZCqo&feature=channel_page
http://www.youtube.com/watch?v=d2xGkYN4v7g&feature=channel_page

JD

Steve,

There is a setting that you can change within the Device Manager to adjust the latency. Windows sets it to 16 by default, and it should be at 1. Are you familiar with the COM settings in the· Device Manager? If not, here is a quick walk through that should guide you.

Start Menu > Control Panel > System > Hardware Tab > Device Manager > Expand COM (PORTS & LPT) > Select the COM > Port Settings Tab > Advanced > Change Latency timer to 1 and click save.

Once you have changed that, go try and download to the BASIC Stamp again; commonly this will fix the issue. If you want, you can call in 888-997-8267 and I will help guide you through those and test it.

Hope this helps,

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Respectfully,


Joshua Donelson
www.parallax.com

SteveWoodrough

Joshua,

Thank you..Works like a charm!

Steve

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Recent Project Videos:

http://www.youtube.com/watch?v=jI79Xsm_Kyk&feature=channel_page

Cool Cars:
http://www.youtube.com/watch?v=SLnPhYKZCqo&feature=channel_page
http://www.youtube.com/watch?v=d2xGkYN4v7g&feature=channel_page