at wits end, sx key not found on com1

Sawmiller

hi folks,
dont know what else to do....
using version 3.1 of the assembler with the led28.src test file from examples , i get a sxkey not found at varying lengths of time when telling it to program...

tried the sxkeyserialtester program found on this board, it finds the sxkey..

sent the sx tech board and key back , dave anders tested them, said they were good...

bought a different com board, (pci) still same problem

reformated hard drive and reinstalled windows xp ( emachines ) still same problem

tried a different power supply, 7.5 vt @ 1 A ,( was using the one parallax supplied) still same problem

it takes a varying amount of time but most times i get a sxkey not found on that short simple program
when just programming it... alot of times the program does get to the chip and the led starts flashing
but sometimes it just gets to the erase stage...

tried the other sx28 also, same symtoms

tried it on a dell laptop, same thing.

I have only got it to debug once then it said communications failled error 144 or some such

is there something i'm missing ?

i want to learn and the sx looked like a good place to start, but these errors are taking up too much time for too lil reward... fustration sets in

anyways rant off...
anything you can figure out i would appreciate it

kjennejohn

a. get a better and/or shorter serial cable.
b. turn off the FIFO in your COM config settings:
- control panel
- system
- device manager
- open Ports (COM/LPT)
- right click on Communications Port (COM1 or COM2), or whichever you're using
- select Properties
- select Port Settings, select Advanced
- unselect 'Use FIFO buffers' at top, left

Hope this helps!
kenjj

Chris Savage

Hello,

·· If you're using a USB to Serial adapter, you made need to adjust Latency settings.· If you're using a desktop, or Laptop with a serial port, you may need to turn off FIFO buffers.· Also, one thing that has had great success for some people on here is putting a 100uF to 1000uF capacitor across the Vss and Vdd leads on the SX Tech board.· Have you tried this?

·· Please confirm your hardware setup from the type of machine, to how it connects to the SX Key and I will see what I can do to help you.· Thanks!

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Chris Savage
Parallax Tech Support
csavage@parallax.com

Guenther Daubach

Chris,

the capacitor must not be that big. According to the specs of the LM2940 regulator, the output capacitor must be at least 22µF, located as close as possible between ground and the regulator's output pin. More important is that the capacitor has a low ESR (Equivalent Series Resitance). Therefore, a tantalum capacitor would be best, or a larger lauminum cap with a smaller tantalum in parallel.

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Greetings from Germany,

Günther

Sawmiller

thanks chris..

the fifo didnt do it , but putting a 1000uF cap did every once in a while it will still give me the sxkey not found, but i can get to the debug screen now..... will have to figure out where to put the cap thou

thanks again for all the help, and if you think of a better way, let me know. dan

Chris Savage

Guenther Daubach said...(trimmed)
Chris,
the capacitor must not be that big. According to the specs of the LM2940 regulator, the output capacitor must be at

Guenther,

·· There was another thread regarding this issue, and I didn't remember what the OP said worked, but I thought it was a larger value capacitor.· I will have to find the thread.

UPDATE:· Yes, the first time this issue was brought up, the OP posted that putting a 1000uF capacitor in and everything worked fine.· That's what stuck out in my mind.· But of course, you're correct, the spec sheet says differently.

http://forums.parallax.com/showthread.php?p=537158

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Chris Savage
Parallax Tech Support
csavage@parallax.com


Post Edited (Chris Savage (Parallax)) : 8/7/2005 9:49:35 PM GMT

Sawmiller

update ...

tried the 22 uF , didnt work as well as the 1000 uF did..

still cant do the debug for any length of time, get a transmit stall on com 1

going to go find a 3 ft serial cable and see if that helps , was using the one parallax sent

tring to write text to the scott edwards serial LCD, ( its the one i have to hand ) it seems a lot harder than the stamp ( using basic ) and when i just do this bit of code i get a lot of what appears noise on the lcd ( it writes other chars) besides the "Hi" .. the wires to the LCD appear short enuf only 3 inches long

Sio var RA.1

main:

·· pause 1000

·· serout Sio,n2400, $0E· '·backlight on·, it doesnt like decimal for some reason

again:

···· pause 100

···· serout Sio,n2400, "H"

···· pause 10··················· ' give the LCD time to breathe

···· serout Sio,n2400, "i"

goto again



anyways i get to play till i get fustrated , then go away... and come back later..

thanks for all the help,

its a nice forum

dan

pjv

Hi Dan;

While I can't point to what your problem IS, I can tell you it's not the length of the cables.

What I suspect is that your PC gets upset.

On occasion I too get the "TRANSMIT STALL" message, but that occurs only when I'm HEAVILY scrolling up/down through the source code on the PC. It seems the PC gets busy with that, and corrupts the link between it and the SX Key.

The Key is quite unforgiving about this, and breaks off the relationship.

Frustrating, I know, but I'm sure the problem lies within your PC or its configuration.

Cheers,

Peter (pjv)