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Is it possible to Build USB - RAW WebCAM Using....

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Offline narit

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Is it possible to Build USB - RAW WebCAM Using....
« on: 16 / May / 2009, 14:54:52 »
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After I have looked on CHDK and PTP for a fews modules.

In this forum. Someone have pointed-out that the minimun interval is around 15 sec;

So Is it possible to build real-time WebCam by hacking and do something with hardware???

In my hypothesis.

If we call
//....
state_shooting_progress = SHOOTING_PROGRESS_PROCESSING;
//....
started();

and then we get an address of raw data using hook_raw_image_addr();

now we use their LEDs to transfer data!!!

   define LED_BLUE 0xc0220084
   define LED_1 0xc0220088
   define LED_2 0xc022008c
   define LED_3 0xc0220090
   define LED_4 0xc0220094

Then use assembly to blink them in 4 bits nibble or any possible protocol.

on the host side (PC). Maybe mcu or some sort of MCU will tap the signal and send it to PC using custom or generic protocal.

Is it possible?
If it is possible, How much possible bandwidth in data transfering (Theoretical with assembly language) ????

Best Regards...




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Offline fudgey

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Re: Is it possible to Build USB - RAW WebCAM Using....
« Reply #1 on: 17 / May / 2009, 05:47:11 »
PTP can be enabled during REC mode and transfer can be active while shooting, getting rid of any 15 second limit that may come from REC/PLAY mode switching. This is not currently available in any CHDK build, though, but it's been experimented before by ewavr and me at least, on a710 and a570 (respectively) in two separate ways. For mine, see:

http://chdk.setepontos.com/index.php/topic,2696.msg25363.html#msg25363
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Offline narit

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Re: Is it possible to Build USB - RAW WebCAM Using....
« Reply #2 on: 19 / May / 2009, 06:43:56 »
Thank you fudgey.

Anyways. I still have somequestions.

In case that I didn't use Linux (on PCs or any embeddeds.)

But I want to send Image data directly to FPGA or DSP.

Is it possible to use this nibble technique?

And for LED Address ...

 define LED_BLUE 0xc0220084

What is 0xc0220084 refered?

Is "0xc0220084" equal to physical mem address or RTOS(DOS) virtual address????



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Offline fudgey

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Re: Is it possible to Build USB - RAW WebCAM Using....
« Reply #3 on: 19 / May / 2009, 16:38:00 »
Quote from: narit on 19 / May / 2009, 06:43:56
But I want to send Image data directly to FPGA or DSP.
Is it possible to use this nibble technique?
And for LED Address ...
 define LED_BLUE 0xc0220084
What is 0xc0220084 refered?
Is "0xc0220084" equal to physical mem address or RTOS(DOS) virtual address????

I don't know, really. I know some leds are driven by PWM, but I don't know if e.g. our old blinker and/or those led addresses control them via the PWM registers or directly from I/O ports or something that links to them in software. Or if that matters for speed or success for what you're trying to do, really. Someone may know better, but most of what we know from addresses such as this one just have been found by reading disassemblies and found to do what they do experimentally.

We're working with next to zero hardware and software documentation here, so trial and error is often your best bet... you can just try toggling them leds and see how fast you clock them from software. And if the leds are slower than your control, replace them with something faster in hardware.

Anyway, I think you could run into problems achieving sufficient data transfer speed or you may run into problems due to not giving Canon firmware time to do its magic in a timely fashion (read: crashes).
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