f. Bootloader
This is for those who build OSD by your self on naked PCB .
All who have assembled board - already have bootloader programmed in chip.
Bootloader is small piece of software in microcontroller for future program and update main software using COM or USB-COM connection with PC .
If you got assembled unit - the bootloader is already programed - so never update OSD by bootloader.hex file
If you build the unit by your self - at first you must program bootloader in to microcontroller using any ISP programmer .
You can use Bascom demo program and LPT with 4 resistors as ISP hardware programmer - will do the job excellent .
Here is sample picture of simple 5 minutes LPT ISP programmer used with Bascom .
Read Bascom help - there are schema and tips, run and install setupio.exe from Bascom folder - that all .
It was made for friend who want to program OSD after firmware fail (some months ago - now OSD is fixed).
Gold pins are from cell phone connector or printer or whatever wires to contact programming pads on OSD - the board is an old PC card cut to dimension .
All connection can be copied directly as on picture (R 220oHm , C 100pF ) - as you see that ISP technology is not so horrible .
Board have pads MOSI MISO SCK RESET GND - so use them .
Also be sure to store fusebits in proper way (picture are from Bascom) :
Then we can program firmware and eeprom by Megaload - using USB cable, eeprom(BIN file) and fonts(Font file) are programmed in GUI communication bookmark.
So remember , program by ISP only bootloader.hex file and fusebits - all rest do by USB cable.
After programming bootloader one time at begining, any future firmware updates you can made by USB cable .
For bootloader I choose MegaLoad software as free , excellent working and not taking space in microcontroller's memory (takes 512words -1024 bytes only) . Using this software we are able to update flash and eeprom memory contents in OSD using USB cable .
To firmware update Megaload must be set to 9600 baudrate and selected proper COM port number (as USB cable) .
Here are for download bootloader.hex file - pack BOOTLOAD16mhz.zip , we must program it to microcontroller by ISP programmer .
Then use MegaLoad PC software for communication with OSD unit by USB cable.
If you have assembled OSD device - the bootloader is already programed inside , so never load bottloader.hex file into OSD as you destroy it (need ISP reprograming) .
Here are some more tip about cheap FTDI bitbang ISP programer http://www.rcgroups.com/forums/showpost.php?p=17947325&postcount=3212