Programming Jig

[ichilton]

Hi,

Just trying to understand these:
http://lowpowerlab.com/wp-content/uploads/2013/01/Moteino_programming_jig2.jpg
http://lowpowerlab.com/wp-content/uploads/2013/01/Moteino_programming.jpg

It looks like you are supplying power to Vin from both the FTDI cable and the ISP programmer.

Isn't that bad?

Shouldn't you only connect the ISP one if you want to do it without the FTDI lead connected?

Also, what do you use the D9 / LED one for? - or did you add the pin just in case?

Thanks,

Ian

[Felix]

The target has to be independently powered when you ISP program it. The ISP power connection cannot power your board (what if your AVR is inside a CNC .. right?). It is only for "sensing" whether the target is actually ON.

Power on D9 was just auxiliary, disregard that one.

[ichilton]

hmm, that's interesting - my programmer has a 5v pin, which I always use for powering the chip bring programmed.

It's one of these:
http://cdn.instructables.com/F6J/R7FF/H5R9EXQ9/F6JR7FFH5R9EXQ9.LARGE.jpg

Ian

[Felix]

Yeah that's not an official one. I use an AVR ISP MKii. It makes no sense to power your target from the programmer.
What if your target needs 1amp of power? Can your USB/programmer provide that?

[ichilton]

then it's not going to get that from the FTDI cable either

[Felix]

Yes but I'm only powering an AVR with nothing attached to it
That's less than 20mA, FTDI can handle ten times that.

[ichilton]

Yep