USB overhead?

[Art]

Hi Guys,
I'm just wondering if anyone has ever noticed any sort of overhead
for enabling USB mass storage device, if not trying to use the MS in an app.
Once the connection is set up, does the CPU still have to work?
or is it handled by another chip?

Why not leave it on all the time in an app like irshell, and have no option to turn it off?

[Ixar]

Maybe is there some power consumption involved ? Like the wifi.

[weltall]

because you are accessing a same device with two different operating system. it's like if you used the same hd for your operating system and at the same time ran it in a virtual machine. either operating systems will cache files/fs and will end up corrupting the file system togheter: that's why it's always discouraged enabling usb in background while using the psp

[Art]

Thanks, that does make sense, but only if the PSP app is going to access the MS once it has loaded right?
I guess irshell was a poor example because you never know when it, or it's user will access the MS with it.

[everlasting]

Thanks, that does make sense, but only if the PSP app is going to access the MS once it has loaded right?

Yes, i think you are right. I have tested to cut the power to a MS inserted and everything stays the same on the PSP, it still show how much memory is left in the MS, even if previously to cutting the power you had entered in the games section of the xmb, after cutting the power it still show the icons of the homebrew and whatever. Obviously the problem comes if you try to load something without powering it ;).
Apart from the data transfer pins the only one left with "OUT" capabilities in the MS is INS (inserted/removed memory stick) and considering that it is only shortcut to ground when the MS is inserted I guess that when you insert/removed a MS an interruption signal is processed, probably as you suggested by a controller. So I don't think there will be any data transfers while not trying to read/write something on the MS.

Why not leave it on all the time in an app like irshell, and have no option to turn it off?

why don't you want to have the option of turning it off?
I'm sure you must be planning something interesting but can't guess what.

[weltall]

well you can also consider the annoyance factor: for example i've frequently the usb cable connected but i don't use it or use it to run psplink/usbhostfs if you try to mount usb in these cases you will make me going to disconnect the device everytime or you will conflict with usbhostfs

[Art]

I suppose my questions are absolute to try to keep the answers absolute.

There is more than one specific application for me.
The one in mind at the moment is my heart rate monitor which could save
every heart rate for an entire workout session at the gym, and include that
data along with session start and finish times to represent on a graph in a PC app,
or another PSP app.
Now, it would be good to have the HRM compose the file, open USB for the
transfer to a laptop PC, and then close USB, and resume it's normal operation,
all without exiting.

Another idea was a program that opens USB so you can copy over an
updated EBOOT.PBP of the same program as you are developing it.
So if that program is set in DAX fw as the autorun program, it can open
USB for the transfer, and then restart itself by resetting the PSP.
I have done this one before, and it worked well.
Art.

[jimparis]

Now, it would be good to have the HRM compose the file, open USB for the
transfer to a laptop PC, and then close USB, and resume it's normal operation,
all without exiting.

Just use a custom USB driver that has no relation to the memory stick for this. The usbAsync stuff in psplink already has this all abstracted if you're lazy.

Another idea was a program that opens USB so you can copy over an
updated EBOOT.PBP of the same program as you are developing it.

Sounds like psplink would do the trick? Or again just use usbAsync.