forums.ps2dev.org

Fluff · Joined: 22 Apr 2005 Posts: 35

Recently i've been exploring the possibility of generating video output on PIC microprocessors for simple games like pong, which are, though simple, entirely possible, such as this breakout game here : http://www.acm.uiuc.edu/sigarch/projects/breakout/
It resulted in me wondering if a similar sort of project would be possible for the PSP, bearing in mind my knowledge of the psp hardware isn't all that great, and neither is my knowledge of writing software for the device, however a few friends of mine weho have written applications for the device before suggested i ask here.

Basically i would like to know the answer to a few questions regarding the psp's hardware, these are as such.
1) What is the comprative voltage range of the audio jack alone, for audio L/R? would it be able to provide a maximum of 1v?
2) I'm aware that the remote connector is capable of providing a constant 2.5v after reading through this thread : http://forums.ps2dev.org/viewtopic.php?p=18903 , but i'd like to know if the voltage to this connector can be modified via software, and if so, what sort of timing for voltage change would we be talking about?

Now bare with me here, i'm aware my lack of knowledge may have already set alarm bells ringing in the 'noob stamp' department, but i'd basically like to ask the blunt question of, just how feasable would it be to generate a video signal in software, either specifically for displaying a specific application or image, or converting data from the framebuffer to a composite video format, and outputting that video signal to a display via either the remote connector or over L or R audio line (leaving the second for mono audio).

jas0nuk · Joined: 27 Apr 2006 Posts: 137

Interesting... from a quick skim over dvemgr.prx reversed by Dark_AleX, it looks like it may be possible to write any kind of data (such as video) to one of the headphone channels, using the sceI2cMasterTransmit function.
In the case of dvemgr.prx it seems to be reading from/writing to device 0x42 which I assume is the Slim's remote socket, so I wonder what the equivalent IDs are for the headphone channels. Has anyone reversed audio.prx?
Of course, that PRX is from the Slim which has extra hardware to produce the video output, but maybe it could be done in hardware (i.e. capture framebuffer and convert it). :/

Art · Joined: 09 Nov 2005 Posts: 647

I think it would be possible using the same method used in the tutorial written
by the author of pic pong and pic tetris.. I assume that is where you're getting
the idea from.
Surely with a few capacitors for buffering, you could produce an audio signal
to achieve a composite video signal without any resistor ladder.
_________________
If not actually, then potentially.

jean · Joined: 05 Jan 2008 Posts: 489

I tried that video PIC thing, and it's very funny....remember that a PIC at 4Mhz produces 1000000 instructions per second....is audio dedicated circuitry capable of doing this?? (...or did i misunderstood the topic?)

adrahil · Joined: 16 Mar 2006 Posts: 277

jas0nuk · Joined: 27 Apr 2006 Posts: 137

Aha, so, could we 1) emulate what DVE is doing in the slim without making everything run slowly and 2) put this data out through one of the audio channels?

adrahil · Joined: 16 Mar 2006 Posts: 277

jas0nuk · Joined: 27 Apr 2006 Posts: 137

Well, audio is easiest, since a headphone jack to RCA connector can be used, and the white (left) channel used as the video connector. But maybe it could be done through the remote control socket?

adrahil · Joined: 16 Mar 2006 Posts: 277

Still a bandwidth problem... Unless your TV supports 320x240 BW resolution...

jas0nuk · Joined: 27 Apr 2006 Posts: 137

Indeed xD But even a monochrome image at poor resolution would be a nice start