Hold+ v2.64 - Battery Saver Plugin

News/release from Torch:

This is a simple plugin I made a long time ago for my personal use. I just found the source code while going through some old stuff on my computer, so I thought I'd clean up the code a bit and release the plugin.

I realize that there are other plugins that feature similar functionality but I wrote my own because I wanted to be sure its coded optimally, as there are a few careless ways in which these functions can be improperly used (the point of this after all is to conserve battery life).

It does the following when the Hold switch is enabled:
* Switches off the LCD backlight.
* Switches off the actual LCD screen.
(This is important because the backlight and actual screen are two different things. You can have an image being displayed on the screen while the backlight is switched off, such that you can see the image if you use a flashlight. You can also have the screen switched off while the backlight still illuminates the powered off screen.)
* Underclocks the CPU to 61MHz
(Sony has changed the clock speed functions such that only certain combinations of speeds work correctly. Simply trying to underclock to arbitrary values will result in the CPU simply running at the stock speed. I have verified that Hold+ successfully underclocks to 61MHz.)
* The original screen brightness and clock speed are restored when the Hold switch is released.
* Prevents the PSP from going into suspend mode if you accidently push the power switch too far when turning off Hold mode.
* Allows operation of the PSP with the display turned off, to change volume, skip songs etc.

Usage:
Turn on the Hold switch to automatically disable the display and underclock the CPU. Turn off the Hold switch to return the CPU to normal speed and enable the display.

If you push the ANALOG UP button when turning on the hold switch, it will only lock the keypad like normal Hold mode. The display and CPU speed will not be changed, so that you can watch videos etc. with the keypad locked.

If you push the ANALOG UP button when turning off the hold switch, the display will remain switched off and the CPU will remain underclocked, but you can operate the PSP. This is useful if you just need to adjust the volume, fast forward/rewind, or to skip to the next song, without unnecessarily turning on the display. To return to normal, push the power switch to the suspend position, or just press the Screen button.

Installation:
You can install it in the seplugins folder, and make an entry in VSH.txt. Thus it will be active in the XMB. Its also possible to use it in games by adding it to GAME.txt, but some games may crash etc., if the CPU is underclocked to such a low value.

Optionally, its also possible to install it in your PSP's flash0 so that it will work without a memory card. For this you can use FreePlay's "NewBTCFNedit" and enable it for VSH mode in the all the PSPBT?NF.bin files. Add it after vshmain.prx.

Advanced:
If you want to change the clock speed to your own values, you can use a hex editor to change them. The offsets in the file for v2.63 are
0x360, 0x364 - CPU,GPU (Both should be same)
0x36C - Bus (Should be half the CPU speed or less)

The values should be entered in hexadecimal. The default value for CPU/GPU is 3C (60 MHz in decimal) and the default value for bus is 1E (30 MHz in decimal).

Note that simply using any arbitrary value will not work. You will have to test and see which values for CPU/GPU and Bus speed work.

Credits:
Thanks to adrahil for helping with preventing the suspend mode.


Changelog v2.64
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While in Display Off mode, you can now also turn on the display by pushing the power switch to the suspend position.

Pressing the Screen button also works but I recommend using the power switch instead, because when you press the Screen button, the firmware sets its internal brightness variable to the next level, even though the screen is functioning at the original brightness. Thus if you leave it idle after turning on the display using the Screen button, and the screen dims due to the PSP being idle, when you press a button it will jump to the next brightness level.

Download and Give feedback Via Comments

I know DA gave us access to that fourth brightness setting that was previously only available when the PSP was plugged in and charging, but has any plug-in ever allowed us to us the "dimmed" version of the lowest brightness setting that we get after a certain period of inactivity? It seems that would be a good battery saving utility while still allowing the screen to be visible indoors.