AXE020 starter pack high digital output reads 0.6V

[webobject]

Hi I have a new axe020 project board and all digital outputs when high read only 0.6 volts, I'd be grateful if anyone could cast any light on this.

thanks.

 

[hippy]

Welcome to the PICAXE forum.

The outputs you are looking at are likely those from the darlington transistor array which are open collector switches, and can only 'short to ground', sink current rather than output current / voltage. Connect the output via a 1K to +V and you will see what you expect.

If you put your meter on the appropriate PICAXE legs ( taking care not to short them to one another ) you will see the actual outputs switching high and low.

 

[chigley]

Take a look at the AXE020 datasheet - the outputs are darlington transistor outputs. This means that they sink current, not source current.

So when you set an output high in your PICAXE code, the darlington output will be in a low state, and vice versa.

Charlie

EDIT: Oooh, Lancashire, where abouts?

 

[webobject]

Thanks Hippy & Chigley, much appreciated. I'm very new, having less than an hour experience with microcontrollers/picaxe. I put my meter on the appropriate pin/ground and saw it working. The darlington array has me confused but I'll get there eventually. I attached my scope instead of an LED for my first "hello world" experience and thought I'd shorted/destroyed something when the desired results weren't shown! I'm in Preston by the way.

Thanks again

 

[hippy]

Far from an accurate model of what a darlington actually is, but you can think of it as if a relay or electronically controlled switch ...

 .----.           .-------(  Output
-|    |------.    |
-|    |-      )   O
 `----'       )    /
              )   O
         0V _|____|__

 

[westaust55]

ULN2803 datasheet

Since you already have meters and 'scopes, one presumes while new to micrcocontrollers that you have some electroncis experience.

In which case you could also have a look at the ULN2803 Darlington array datasheet. There is a schematic representation of each transistor on page 2.
http://www.datasheetcatalog.org/datasheet/SGSThomsonMicroelectronics/mXssxrt.pdf

 

[webobject]

Thanks again Hipppy, and thanks westaust55 for the data sheet.
I armed myself with equipment from ebay prior to setting off on my
electronics/microcontroller odyssey. My electronics experience is
limited but I thought I'd go for the immersive approach!

 

[Minifig666]

I wish I had a scope am a meter when I started out, come to think of it I still want a scope.
Once you've got the basic theroy 'soldered' in the worlds your oyster. I wish you luck with your odyssey. A few good points of refrence I have used along my way include:
The electronics club: http://www.kpsec.freeuk.com/index.htm
Instructables: http://www.instructables.com/technology/electronics/
Just googleing things always helps.
The forum and it's search tools.