DSLR main board : interesting chip

[Mat]

Hi guys,

A friend of mine gave me an Canon EOS 1100D that had water damage. While disassembling the body, something caught my eye. A fiber runs down from the flash unit on the top to some kind of light sensitive chip through a clip-on plastic part.

Does anyone know what could the purpose of that chip be, and if its a custom chip or a standard part.

Thanks in advance,
M.

[andy_silicon]

Probably related to either flash trigger or white balance.
Or maybe simply light level to determine if the flash should be fired.
I've also noticed it in an Eos 450D/550D

[amyk]

Likely for measuring the light output of the flash. Almost certainly a custom part.

[SeanB]

Nice photo of the sensor. Looks like it has a large area photodiode ( black block in bottom right on chip) and then an amplifier and an ADC after it, then the rest of the chip is taken up with what looks like a mask programmed microcontroller to process the data and send it to the rest of the camera. Looking at the ROM it is what looks like 12 bits wide, so probably the core is a PIC microcontroller soft core with some custom analogue circuitry added to it.

[T3sl4co1l]

That whole half of the chip with the 12 columns, looks more like a sea-of-gates to me.  Note the top layer interconnects are mostly horizontal, zipping back and forth irregularly.  If there is ROM, I doubt it's visible on this magnification (nice pic BTW!), though that gray blob near the sensor could be some -- or it could be something boring like the compensation capacitor for an amplifier section, or perhaps charge pump for onboard supplies (negative might be handy for analog, or it could be positive for flash, if any).

Why a sensor needs so much logic is beyond me.  There could very well be an MCU in there.  Not quite enough for an ARM I think (it doesn't look that fine-pitch to me), but anything below that?

Unless I'm missing something and the pattern is, in fact, a close match to a PIC core or something!

Tim

[Mechatrommer]

i second andy_silicon for white balance control. i have spyder colorimeter and spectrometer whatever the name is, one is to measure color from paper (it has built in rgb light source), another one is to measure color from monitor (light source is from monitor, no built in light source). along the path from light source to the sensor is that greenish rectangle glass or transparent plastic. both the colorimeter and spectrometer whatever the name is have that. the spyder is not cheap, well its the cheapest in its class but way "not cheap" compared to a laser mouse, i'm guessing because of the sensor cost.

[marshallh]

If you're interested I can put you into contact with someone who will do high resolution imagery of the die pro bono

[Mat]

Very enlightening answers guys, thanks!

If you're interested I can put you into contact with someone who will do high resolution imagery of the die pro bono

That would be interesting, I already returned the camera, but let me get back to its owner and I let you know.

Thanks for the compliments on the picture! I used my Nikon D5000 with the 18-55 kit lens in a reverse mounted configuration.