Download Problem

G

giuseppe

Member
Hello all. I seem to be having a problem with downloading a program onto the picaxe chip. It is a 08M. I have an axe027 usb cable.

I am able to successfully download the program from my desktop but have a problem with my laptop recently. When I test the serial in port on the desktop, the voltage is 4.9V when it is turned "high". However, when I test the port from my laptop, it only reads 2.3V when turned "high". Anybody have such a problem?

--- What I have tried ---
I have tried reinstalling the driver files on all usb ports and tried them. I have tried uninstalling the driver files on all but one usb port. I have updated the programming editor and restarted my computer. The port however still reads 2.3V
 
A

alband

Senior Member
I wont be able to help (too stupid) but what operating system are you using on both machines?
 
G

giuseppe

Member
Well the one that works is running windows XP and the one that is not working (but used to) is running windows vista.
 
hippy

hippy

Ex-Staff (retired)
It does sound like a hardware issue rather than software. The AXE027 takes its power from the USB port and that should be 5V whether desktop or laptop.

Is the AXE027 plugged into the same PICAXE hardware in each case ? My feeling is that it may be the PICAXE hardware rather than AXE027, perhaps an issue with the download circuit. What PICAXE hardware are you using ?
 
A

alband

Senior Member
What changes can you thin of between when it did work, to when it didn't. e.g. Vista updates, code changes...
 
C

chigley

Senior Member
It seems strange, as you're reporting that your circuit does work when downloading from your desktop, but are you sure that your 22k and 10k download circuit resistors are the right way round?

2.3V sounds close to the voltage you'd expect if they were wired as a potential divider. No idea why it'd work from your desktop though if this were the case - you'd have to wait for an expert to explain that one :)
 
M

MPep

Senior Member
chigley said:
It seems strange, as you're reporting that your circuit does work when downloading from your desktop, but are you sure that your 22k and 10k download circuit resistors are the right way round?

2.3V sounds close to the voltage you'd expect if they were wired as a potential divider. No idea why it'd work from your desktop though if this were the case - you'd have to wait for an expert to explain that one :)
Click to expand...
Simple. The desktop probably outputs +/-12V, therefore it would work normally. Rounded calculation here, but if a swing of +/-10V were available, then you'd have 2x 2.3V = 4.6V which would be acceptable to the PICAXE.

Definitely check the polarity of the resistor network.
 
G

giuseppe

Member
Well I am using a PICAXE 08M. This is just the chip and is being powered by a powered breadboard giving 5V from a banana plug screw terminal. I did not change the circuit at all when I go from laptop to desktop.

No I do not think I have gotten any new updates for vista, I have just recently changed my laptop battery to a newer one and a new AC adapter but I do not think that is the problem at all.

I also measured the voltage straight from the 3.5mm jack and it is 2.3V as well so the voltage is not divided. Wouldn't divided voltage be 1.56V and 3.4V?

I also have the download circuit soldered to a prototype board a bought from radioshack since I was tired of assembling the same old circuit on the breadboard.

Here is the schematic: http://mail.google.com/a/njit.edu/?ui=2&ik=c51f6fffac&view=att&th=12905370b6d54cf6&attid=0.1&disp=inline&zw
 
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C

chigley

Senior Member
Please take some hi-res photos of your circuit and post them here so we can check your wiring.

Charlie
 
G

giuseppe

Member
I cannot take high res photos.

I tried the desktop again and it still works and I just tried it on my laptop and now it downloaded....... :confused:

I am not too sure why it works now as I did nothing to try to remedy it other than switching back and forth from computers. Maybe there is cold solder joint I am not aware of that is causing sporadic behavior. Would a loose connection bring about such a situation?
 
A

alband

Senior Member
This seems extremely odd. Perhaps post your code so that if anyone eles has a Vista machine they might be able to run it to check. Also, have you tryed using the USB cable on the other XP machine since it didn't work on the Vista machine? If not, it is possible the chip is now broken and is therefore not downloading. This in turn could possibly also have bust the cable, so best check.

Good luck with it. :)

Edit, just got your previous reply. Sounds to me like the chip needed resetting and for some reason only the XP machine could do this. Keep trying it on the Vista machine though in case it was a fluke.
 
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M

manuka

Senior Member
Is this laptop just battery powered? Back in the late 90s Basic Stamp era my Thinkpad laptop would only BS program when mains powered, as port voltages otherwise were too low.
 
D

Dippy

Moderator
I tried your schematic link and got a Webmail by Google window ????

Personally, I'd 'scope it and watch it real time.
If you think you have dodgey connections then that's down to you and your soldering iron I'm afraid.:(
 
G

giuseppe

Member
Hello, just want to update all.

I re-soldered all of my connections and have been programming with both machines and everything seems to be fine. I am going to suspect it was a solder joint that was loose. My laptop has programmed it with and without a battery.

Dippy, sorry for the link not working. I attached the schematic. I made the schematic first off of my protoboard connections first so I could compare it to the download circuit. It looks identical to the circuit in the picaxe manual.

Thanks to all again for your thoughts and help!
 

Attachments

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hippy

hippy

Ex-Staff (retired)
Sounds like you've fixed it and thanks for letting everyone know.

It would be worthwhile running the serial port test on your laptop again and checking the voltages if you haven't, just to ensure the voltages are now as expected, nearer 5V, that it's not just a slight increase in voltage overcoming whatever problem there was.
 
I

inglewoodpete

Senior Member
Still Wrong

That circuit IS NOT the correct download circuit:rolleyes: Your drawing is the (incorrect) voltage divider circuit that members have referred to in previous posts.

You will have ongoing problems with your laptop until you change the circuit. Please go to Manual 1 - Getting Started/Download Circuit and change your resistor connections to match those in the manual. The computer 'send' leg must go to the junction of the two resistors.
Edit: Yep, Giuseppe and Martin are right. I must have been standing on my head when I read the circuit!
 
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