Rpi Screens

The following display outputs are supported on the board:
 * Composite video (NTSC and PAL) via an RCA plug. (the yellow plug on your tv)
 * HDMI 1.3a standard output.
 * Display Serial Interface (DSI) - via unpopulated 15-way flat flex connector.

These interfaces allow the use of a broad range of displays, including:
 * Televisions (HDMI or composite).
 * Computer monitors (HDMI/DVI-D cable) (VGA monitors would require either a composite or HDMI to VGA scan converter box).
 * DLP/Laser Pico Projectors (HDMI/DVI-D cable).
 * RAW LCD panels (DSI + interfacing hardware)
 * Composite and HDMI outputs can not be used at the same time (one or the other.)

HDMI
Directly from the board.

DVI
With a passive HDMI to DVI convertor or cable.

Composite video
Composite video (NTSC and PAL) via an RCA plug, directly from the board.

VGA
The Broadcom BCM2835 only provides HDMI output and composite output. RGB and other signals needed by RGB, S-VIDEO or VGA connectors are however not provided.

A couple of options for VGA or component RGB outputs, bridging from either HDMI or the MIPI DSI interface:

Firstly, the following *might* work. Beagleboard people have reported various levels of success (mainly "issues"):

http://www.hdfury.com/

Something similar:

http://www.fit-pc.com/web/fit-pc2/accessories/fit-vga/

...it may need to be modified as described here:

http://blog.galemin.com/2011/03/dvi-d-to-vga-converter-for-beagleboard-xm/

Alternatively, it may be possible to design an expansion board that plugs into the LCD headers on the R.Pi. Here is something similar for Beagleboard:

http://boardzoo.com/product_info12.php

Some more converters that should work:

$24.00 ASUS - Video adapter

$27.77 HDMI Male to VGA RGB Female Video Converter

$39.99 HDCP HDMI to VGA + SPDIF RGB Component Ypbpr Converter

$48.00 HP HDMI to VGA Display Adapter


 * The SOC(system on a chip) does not support any kind of analog component video, including VGA, since the SOC is designed for mobile phone use where this would not be a requirement.
 * Additional componenty would be needed to generate RGB signals. Additional componentry would push the price beyond the $25 target and therefore won't happen.

interfacing to Raw LCD panels
Nokia N900 has 800x480 DCS LCD (afaik its like DSI, but has build in framebuffer). Replacement screen is about ~$40 (~$50 with 4pin resistive touchscreen).

Nokia N8 has AMOLED 360x640 pixels DSI LCD. Replacement screen is about ~$35, another ~$25 for Multitouch Synaptics T1021A touchscreen (I2C + interrupt IO, no docs/drivers).

Potential LVDS interfacing chips :

TC358764/5 Display Bridge (MIPI® DSI to LVDS)

DVI receiver TFP401A, TFP403, or TFP501 + LVDS transmitter SN75LVDS83B or SN65LVDS93A (Mentioned earlier fit-VGA is build around TFP401A, probably many more "active" DVI2VGA cables are build the same way)

I2C/SPI ADC can be used to interface 4 pin resistive Touch Screens, For example STMPE812A

16x2 LCD Displays
The old-style 2-line, 16-character LCD displays can be commonly controlled over UART, thus providing a cheap way to display values for sensors etc.