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iMac internals & Infrared?

 
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kuro
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PostPosted: Thu Oct 27, 2005 7:54 am    Post subject: iMac internals & Infrared? Reply with quote

Hi,

Any electronics engineers out there been brave enough to open up their brand new iMac yet?

I'd be very interested to learn how the Infrared is implemented.

I am guessing it is a very simple circuit - IR receiver connected to the I2C bus (does Mac have I2C?) or similar wireline bus via a tiny IR receiver IC. Perhaps it is even using some of the interrupt lines previously used for the built-in modem (only a USB modem is available for the new iMacs)?

The interrupt is probably configured to trigger on both rising edge and on falling edge and call a routine that takes a timestamp and sticks the result in a buffer. Later, a thread would process (some of) the buffer to work out the IR code and take the appropriate action (perhaps by inserting the appropriate keycode into the keyboard buffer).

If this is the case, it would be pretty straightforward to add an internal IR receiver to pretty much any Mac that isn't using those interrupt lines for something else. On the Mac Mini, one could replace the white power LED with the receiver LED or carefully drill a tiny hole on the left-hand-side of the case.

Anyone up for the challenge?
--
Michael

Edit: It looks like the modem (when fitted) is acually an internal USB modem (iMac G4) or connected via the I2S bus (iMac G5 and Mac Mini); the Intrepid ASIC provides an I2C bus which is used for configuring memory among other things.
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g5g5
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PostPosted: Thu Oct 27, 2005 8:32 pm    Post subject: Reply with quote

That's way beyond my technical skills. I just wanted to let you know that it sounds like a cool idea. I just hope Apple beats you to the punch. No offense! Wink

Here are some pictures of one disassembled.
http://www.kodawarisan.com/imacg5_isight/imacg501i.html
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kuro
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PostPosted: Fri Oct 28, 2005 5:42 am    Post subject: Reply with quote

g5g5 wrote:
I just hope Apple beats you to the punch. No offense! Wink


Heh, no problem Very Happy

I very much doubt that we'll see an Apple IR solution for the existing Mac Mini. 3rd parties have got dongles already and unfortunately the USB ports are at the back so any external IR solution for the existing Mini is going to be inelegant. A Bluetooth version of the remote is a possibility, as is a new Airport Express with IR and video, I guess.

A more likely scenario is a another minor itteration of the Mac Mini with built-in IR and other goodies (perhaps an improved GPU), but that still leaves us existing users out in the cold.

Thanks for the link - I had come across that already but unfortunately the resolution is far too low to determine anything useful.
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poisonfist
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PostPosted: Sat Nov 26, 2005 12:25 am    Post subject: Reply with quote

Bluetooth sounds more attractive, and an elegant solution to adding a remote. Although adding an IR function to a current Mini would definitely be bragging rights.

My current solution of using my BT cell as a remote is good enough for me though.
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