Any known way to change the clock speed? - page 2 - General Discussion and Assistance - CHDK Forum

Any known way to change the clock speed?

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Offline reyalp

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Re: Any known way to change the clock speed?
« Reply #10 on: 30 / October / 2009, 21:23:10 »
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ARM946E-S Technical Reference Manual
2.3.10 Register 7, Cache Operations Register
Quote
Wait for interrupt
This operation enables the ARM946E-S processor to enter a low-power standby mode.
When you invoke this operation, the processor core is halted and the cache and TCMs
are placed in a low-power state until either an interrupt or a debug request occurs. This
function is invoked by a write to register 7. The following ARM instruction causes this
to occur:
MCR p15, 0, Rd, c7, c0, 4; wait for interrupt
I know the canon (or vxworks) code uses this in some places.
Don't forget what the H stands for.

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Offline RaduP

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Re: Any known way to change the clock speed?
« Reply #11 on: 30 / October / 2009, 22:09:11 »
Ok, that actually helps a lot! Thanks.
The watchdog does not kick in, and the camera remains almost frozen in a tight loop that calls a function with that instruction..

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Offline RaduP

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Re: Any known way to change the clock speed?
« Reply #12 on: 30 / October / 2009, 23:30:25 »
I managed to turn the lcd off (and back on) in conjunction with the HLT like instruction.
Now, do you know any function that can turn the CCD off/on? I swear I've seen a string like that a while ago, but I can't find it again :/

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Offline reyalp

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Re: Any known way to change the clock speed?
« Reply #13 on: 30 / October / 2009, 23:33:29 »
When the display is turned off (with the disp button on cameras that have it), the live view buffer also stops updating.
Don't forget what the H stands for.


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Offline RaduP

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Re: Any known way to change the clock speed?
« Reply #14 on: 30 / October / 2009, 23:48:38 »
My camera doesn't have this button, so I use DispSwCon_TurnOffDisplayDevice()
I guess the best way to check is to look at the sensor temperature before and after the 'hibernate' function.

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Offline RaduP

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Re: Any known way to change the clock speed?
« Reply #15 on: 31 / October / 2009, 03:39:13 »
I did some more tests, the CCD is NOT turned off when I call DispSwCon_TurnOffDisplayDevice...
Can you please do a test for me?
Set the camera to display the CCD temperature, wait for a minute or so until it gets to 28C+, then press the display off button, leave it like that for a minute or so, then check the CCD temperature again.

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Offline RaduP

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Re: Any known way to change the clock speed?
« Reply #16 on: 31 / October / 2009, 05:20:45 »
Nevermind, I tested it on my A570, and the temperature does decrease when the display is blanked..
Now, if I could only find the CCD power off function..

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Offline RaduP

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Re: Any known way to change the clock speed?
« Reply #17 on: 02 / November / 2009, 00:50:19 »
Well, still didn't find the CCD power (although I found some MMIO that does something to the CCD :D), but I noticed that the SD power is always on, and turning it off then on seems to work fine..
Also, when reading the SD power location, the number displayed is 0x47 instead of 0x46. Kind of interesting.


 

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