Axon 2 programmer question

[richiereynolds]

Hi there, on my latest (axon 2 powered) bot I've mounted the circuit board from inside my avrisp mk2 programmer on the bot itself, mainly so that I don't keep forgetting where I've left it, but also so I just have to plug the usb cable in to program it and can leave the 6 pin programmer cable connected to the axon all the time.
It's a bit of a pain to remove/reconnect it all the time, plus I'm sure that eventually I'd weaken and damage one of the axon's programmer pins.

Anyway, I've found that this all works fine and the axon runs when the programmer is powered via the usb cable but when I disconnect that the axon freezes i.e. it won't run with the (unpowered) avrisp connected.

Is there any way round this? Can I supply the needed power via some other pins on the axon? Or is there a way to make it run with these pins connected but not powered?

Cheers, Richard.

[Soeren]

Hi,

It's a bit of a pain to remove/reconnect it all the time, plus I'm sure that eventually I'd weaken and damage one of the axon's programmer pins.

Why not simply cabling a connector to the ISP port (and then tie the interface to the extension lead from your PC), then, when you wanna make a new 'bot, you don't need to buy a new programmer

Anyway, I've found that this all works fine and the axon runs when the programmer is powered via the usb cable but when I disconnect that the axon freezes i.e. it won't run with the (unpowered) avrisp connected.

Is there any way round this? Can I supply the needed power via some other pins on the axon? Or is there a way to make it run with these pins connected but not powered?

I have not studied the Axon, but I'd imagine that the reset is pulled low when an unpowered programmer is connected (that would freeze it).
If that is indeed the issue, you could disconnect it with a transistor, reed relay  or whatever, but I'll still suggest to just mount the ISP port to a more user friendly connector (that is, if you want a connector*) like eg. a 5 pin XLR, a 5 pin DIN connector (locking or not), a Dsub-9 connector, or any other 5 (or more) pin connector that's reliable and easy to plug/unplug.

*If you're plugging and unplugging really often, like 5..10 times a day each day, most plugs will wear down in no time. I have used IR comms to counter that specific issue, where gold plated connectors were skinned of the gold in less than a month, giving intermittent contact and hence unreliable data transfer. The easy way to do it is by magnetic coupling.
With a bit of dexterity, it could even be made as a self docking station.
You would need 3 channels (MISO, MOSI and Reset) and they would need to be shielded to avoid crosstalk. And it would need to run from the battery while being programmed of course.

[Admin]

Hmmmm I once saw this happen to my Axon II powered ERP . . . it only worked while my ISP programmer was powered up . . . it never happened before for months, then suddenly it started happening.

I'm not sure if its a problem with the programmer or with the Axon, to be honest. But I'm assuming the hardware programmer is somehow affecting the reset pin negatively.

Just some thoughts . . . check the voltage across the tiny black resistor next to the ISP header in each situation and report back.

You can also try removing the resistor . . . not sure if it'll work better, though, but I think its worth a try.
(fyi, its a 300kohm)

[richiereynolds]

Why not simply cabling a connector to the ISP port (and then tie the interface to the extension lead from your PC), then, when you wanna make a new 'bot, you don't need to buy a new programmer

Well, it's not a permanent mounting, easily moved for when I want to switch to another bot.

but I'll still suggest to just mount the ISP port to a more user friendly connector (that is, if you want a connector*) like eg. a 5 pin XLR, a 5 pin DIN connector (locking or not), a Dsub-9 connector, or any other 5 (or more) pin connector that's reliable and easy to plug/unplug.

That's an excellent idea, much rather wear out a cheap connector than weaken connections on the axon, thanks!

Hmmmm I once saw this happen to my Axon II powered ERP . . . it only worked while my ISP programmer was powered up . . . it never happened before for months, then suddenly it started happening.

I think it was the same on my $50 robot.

check the voltage across the tiny black resistor next to the ISP header in each situation and report back.

will do, though with my soldering, I'd be loathe to try to remove it!

[richiereynolds]

With the avrisp powered via usb it's 0.25V across that resistor. If I unplug the usb it's 4.28V.