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SX-Key not found on COM1 (not broken and has power) — Parallax Forums

SX-Key not found on COM1 (not broken and has power)

ichidanichidan Posts: 8
edited 2005-10-28 16:40 in General Discussion
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.

Comments

  • BeanBean Posts: 8,129
    edited 2005-10-14 23:31
    If you are running the pico from batteries, try new batteries. The pico will run down to 2.7volts, but the SX-Key NEEDS 5.0 volts.
    Bean.

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    Product web site: www.sxvm.com
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    ·
  • ichidanichidan Posts: 8
    edited 2005-10-14 23:55
    Bean (Hitt Consulting) said...
    If you are running the pico from batteries, try new batteries. The pico will run down to 2.7volts, but the SX-Key NEEDS 5.0 volts.
    Bean.

    Hmm, you know I've been thinking it could have something to do with the power supply... I'm actually using a 4.5V (600mA) DC power supply (goes thru a 7805 +5V voltage regulator). Initially I was using a 9V battery, which after about an hour or so of use I started getting such SX-Key not found errors, and I switched to a 9V (1000mA) power supply, which worked, but was making the 7805 quickly get hot, so eventually I went over to the 4.5V (600mA) DC power supply which I'm using now, cause I didn't want to burn anything out [noparse]:)[/noparse]

    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?).
  • dkemppaidkemppai Posts: 315
    edited 2005-10-16 03:02
    ichidan said...
    ·

    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?).
    Here's an idea...··· ...you can·use the PC itself for a·DC power supply. I just hook a 5 foot pigtail to a spare power connector in the PC.·PLEASE NOTE. USE FUSES! just in·case you short things out (I usually put them in the PC).

    No need for regualtors!, and makes a handy supply that·you never forget to shut it off when
    you're done!

    -Dan
    ·
  • ichidanichidan Posts: 8
    edited 2005-10-16 14:36
    @dkemppai. Yeah I actually tried that (both going thru the 7805 and directly powering the Pico). it sufficiently powers the pico. but i still get SX Key not found on COM1/COM2. I'm pretty sure it's a problem with my COM ports (I'll have to either reinstall Windows and maybe that'll fix it, or my COM ports are messed up physically, and I'll have to use a different computer to communicate to the Pico [noparse]:([/noparse]).
  • dkemppaidkemppai Posts: 315
    edited 2005-10-17 17:06
    ichidan said...
    @dkemppai. Yeah I actually tried that (both going thru the 7805 and directly powering the Pico). it sufficiently powers the pico. but i still get SX Key not found on COM1/COM2. I'm pretty sure it's a problem with my COM ports (I'll have to either reinstall Windows and maybe that'll fix it, or my COM ports are messed up physically, and I'll have to use a different computer to communicate to the Pico [noparse]:([/noparse]).
    If you are using the 5 volt supply from your computer, do not use the 7805. The 7805 requires that the input voltage is about
    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
    ·
  • ElectronegativityElectronegativity Posts: 311
    edited 2005-10-17 17:34
    My experience has been that the SX key stops working around 4.5 volts.
    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...
  • Philip GamblinPhilip Gamblin Posts: 202
    edited 2005-10-28 05:39
    I have experienced weird com port issues with USB ports and specifically serial to USB adapters. I have used a loopback cable with hyperterminal to positively identify a com port and baud rate.
  • william chanwilliam chan Posts: 1,326
    edited 2005-10-28 14:36
    You know I have been having "SX-Key not found on COM1" problems with my SX-Key rev. E for a long time with nobody being able to help.

    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?
  • Chris SavageChris Savage Parallax Engineering Posts: 14,406
    edited 2005-10-28 16:40
    William,

    ·· 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
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