This is a mini Arduino based on-screen display board. It's tailored for use with ArduPilot Mega and the MAVlink protocol, and designed to be as small as possible.
It's main components are an ATmega328P 8 bit microcontroller with an Arduino bootloader, and a MAX7456 monochrome on-screen display. Programming is done through an FTDI-compatible 6-pin cable.
It features two independent power and ground sections to isolate the OSD's analog stage: a +5V section for the ATmega and the OSD's digital stage, powered through the FTDI cable or other +5V source; and a regulated +5V section for the OSD's analog stage, powered through the video in/out header and capable of handling up to +12V input.

Features:
? ATmega328P with Arduino bootloader
? MAX7456 monochrome on-screen display
? FTDI cable compatible pinout
? Standard 6-pin ISP header
? Two independent power sections with an LED indicator on each
? Solder jumpers for combining the power sections
? +5V 500mA regulator for up to +12V supply input (5-12v range)
? Solder jumper for PAL video option
? Exposed test points for HSYNC and LOS

the software to change settings/customize the OSD is here: