SX-Key not found on COM1 (not broken and has power)
ichidan
Posts: 8
I've got an SX-key with the XGS Pico Edition kit. Everything seemed to work well on the first day of using it. I could flash the SX-28 processor, but then I started getting 'SX-Key not found on COM1' error messages using the SX-Key v3.0 software. I tried using the same software, key, processor etc. on another computer and it works fine. So I know the SX-Key, Microcontroller etc. are still working fine and not broke [noparse]:)[/noparse] - but i think something is now wrong with my computer's COM1/COM2 ports. Either it's a hardware thing or a software thing. I've tried a few pieces of COM1/COM2 software, and having a cable connecting COM1 to COM2 and data seems to be sending/receiving thru ok.
So I'm just posting to see if anyone else has experienced something similar and has a remedy.
So I'm just posting to see if anyone else has experienced something similar and has a remedy.
Comments
Bean.
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"Save your money. Pay with cash."
·
Now for some reason it worked initially with this power supply on my computer, and then stopped working, but still works on my brother's computer. Perhaps somehow the COM ports on my brother's computer are providing some extra voltage to the SX-Key to help it out or something.·I guess the 4.5V power supply is very much border line. Matter fact, I think the 7805 voltage regulator shouldn't take input voltages that low ( http://www.national.com/pf/LM/LM78M05.html· says Min: 7.20Volt, Max:35Volt - also says Max Temperature 125 degrees!!!, maybe I should go back to the big 9 Volt·monster and not worry about the 7805·getting hot?).
No need for regualtors!, and makes a handy supply that·you never forget to shut it off when
you're done!
-Dan
·
2 volts above the input voltage (at 5 volts in, the output will be around 2.5 to 3 volts!)·Just wire the 5 volts from the PC directly to the SX-key. Are you checking your 5 volt line to the SX-Key with a volt meter? It's good idea to make sure that it's actually getting 5 volts.·
-Dan
·
Usually I get a few "Transmit stall on com 1" messages before the "SX key not found"
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I wonder if this wire is hot...
So, I finally decided to do something about it once and for all.
I went out and bought a $600 digital bench power supply and used it to power my numerous projects that couldn't be programmed by SX-Key rev E but can be programmed by SX-Key rev F.
And guess what, it works all the time now using the bench power supply.
I switched back to the Made in China 12V adapter, the SX-Key rev F cannot program again, even if you try 10 times.
I have 5 different brands of 12V adapters, all of them doesn't work with SX-Key rev E on many projects.
So, the conclusion is SX-Key rev E requires a very stable (ripple free?) power supply wheareas SX-Key rev F is more accomodating.
Any explanations from Parallax engineers?
All my mentioned projects use 7805 regulators, converting 12V to 5V.
I always place a 450uF Cap before the 7805 and a 220uF Cap plus a 0.47uF Ceramic cap on the 5V rail.
How to make the supply more acceptable to SX-Key Rev E?
·· I would try to form an explanation for you, but...Since we are unable to duplicate your results here with the same Rev SX-Keys that would be difficult at best.· I have both on my bench, and they both work on the power supplies we sell.
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Chris Savage
Parallax Tech Support
csavage@parallax.com