An interesting AVRISP2 modification

Go To Last Post
7 posts / 0 new
Author
Message
#1
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Check out how this guy modified his AVRISP MKII.
http://www.webx.dk/avrisp-mk2-mo...
Since it's powered by USB, why not give power to the target too?

This makes me wonder why Atmel did not build it this way to begin with.
Or at least with the option (jumper?) to have it source some power.

Seems very useful!

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I had hacked n USB cable from a broken USB-232 converter, and added a jack plug to the +5V line. Then why I have to modify my dear USB ISP if I have another free USB?

Guillem.

Guillem.
"Common sense is the least common of the senses" Anonymous.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Because you are only allowed to draw 100mA before enumeration. That's not to say that the AVRISPMkII enumerates as a high power device, but it is one reason to hack a USB device and not just a cable.

Edward

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

There is another reason. Atmel likes the target board to power the interface so it will be the correct voltage, such as 3 volts or 5 volts.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Cheers,

Tom

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

The STK500 can source quite a bit of power when used as an ISP.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

rneil wrote:
There is another reason. Atmel likes the target board to power the interface so it will be the correct voltage, such as 3 volts or 5 volts.

I think this is a very valid point. Having the ISP or ICE able to supply Vtg is a useful option, but I know that where I work it would not happen - we have things like 3.1V and 3.8V supplies on various boards as well as the more common 2.7, 3.0, 3.3 and 5V.

Dean.