Can Dandelion CPU be reprogrammed?

[toups]

Does anyone know which CPU/PIC is being used in a Dandelion chip?

Can it be reprogrammed using the existing contacts?  (I am talking about reprogramming the actual code in the PIC via an SPI interface and not the data as is done via the camera interface.)

[golunvolo]

I'm pretty sure you can program it from a camera. The D700 does that and probably some others

[toups]

Yes I know how to reprogram features with a camera. 

What I want to do is change the actual program or firmware in the chip.  For example, having the chip report a different code rather than type G and changing some of the focal lengths available to be reported (that are supported by Nikon cameras but not the Dandelion chip.)

This may or may not be possible depending which PIC chip is being used, which pins are connected to the Nikon camera interface, and whether the protection bits on the chip have been programmed.  I believe for some chips, even if read/write protected, they can still be completely erased to allow reprogramming.  So for PICs, you may not be able to read the existing code, but you may still be able reprogram the chip with your own code.

[Bruno Schroder]

No idea if it is feasible but it would be interesting. I'm meeting a group of camera hackers this Tuesday. I'll ask them if they have any experience with it.

[toups]

Managed to find an image of the internals of a Dandelion chip on this site at https://nikongear.net/revival/index.php?topic=6603.msg190595#msg190595

Haven't been able to identify yet which chip is being used from the numbers I can see.  Interesting, I only see 1 resistor in the image.  I have a damaged Dandelion chip but the contacts are still good, so not in a hurry to open it up if I don't need to.

Have a cheap AF macro extender that I intend to add wires to be able to both monitor communications between the camera and lens and also use an Arduino to either emulate a lens or camera to experiment a bit.  Hoping that the wiring of the chip is such that it could be re-programmed using the existing contacts.

It may be a while before I can get back to this project.

[toups]

Managed to find an image of the internals of a Dandelion chip on this site at https://nikongear.net/revival/index.php?topic=6603.msg190595#msg190595
... Interesting, I only see 1 resistor in the image....

I take that back, it might be a capacitor instead.  Hard to tell.

[Erik Lund]

Yes I know how to reprogram features with a camera. 

What I want to do is change the actual program or firmware in the chip.  For example, having the chip report a different code rather than type G and changing some of the focal lengths available to be reported (that are supported by Nikon cameras but not the Dandelion chip.)

This may or may not be possible depending which PIC chip is being used, which pins are connected to the Nikon camera interface, and whether the protection bits on the chip have been programmed.  I believe for some chips, even if read/write protected, they can still be completely erased to allow reprogramming.  So for PICs, you may not be able to read the existing code, but you may still be able reprogram the chip with your own code.

I guess your best option is to source some of Birnas CPU's second hand from members here on NikonGear and let Birna progam them to your desired lens specs.
This therad sums up the situation pretty well:
https://nikongear.net/revival/index.php?topic=32.0