USBprog bootloader (conception and handling) 
Benedikt Sauter, 4.11.2007, sauter@ixbat.de The bootloader provides the platform for a simple exchange of the firmware. Since there have been a few problems with the old version of the bootloader under Windows the new bootloader has been developed. There is further information on the handling and the conception in the sections down below on this page.
State No errors or problems are known.
Downloads- Bootloader (hex)
- Bootloader (bin)
- Source code archive (svn)
ATTENTION With the new bootloader lfuse have to set to 0xe0 and hfuse 0xd8!!! Conception Primordially, the boodloader should simply be activated with a computer program. Under GNU/Linux it worked just fine, but under Windows there were unfortunatelly a lot of problems. The problem seems to be the driver stack of Windows. Under GNU/Linux you can access any USB device with the library libusb for example without an additional driver installation. In Windows you still have to install a driver for each device under the libusb, even when you use the library. And this was a common source for errors. Often Windows doesn't know which driver to load when you change the firmware and thus the ID of the USB device while it's running. For that reason you can now start the bootloader manually with a jumper. Thus the problem of changing IDs during a session doesn't occur anymore and Windows doens't have to reload a driver. In the next section is described how to use the bootloader. 
Fig. USBprog TX,RX Jumper: bootloader start-jumper
How to use the bootloader The bootloader can be startet with a jumper. If the jumper is set between TX and RX when plugging in, the bootloader will be startet. When the bootloader is active, the LED blinks in a certain rhythm: ..long off - shortly on - shortly off - shortly on - shortly off - long off. After the bootloader is startet you can either change the firmware easily with the graphical user interface or with the console program. The jumper should be removed afterwards, because otherwise the bootloader will always start and not the newly installed firmware. Linux: Under Linux the boodloader can still be started via USB without the jumper.
Windows: On some Windows installations you can also start the bootloader via USB without jumper (with flashtools). But under a lot of Windows versions it just causes problems. Under this versions you should always proceed like that:
- set jumper first
- plug in USBprog
- chose and transfer the firmware with a flashtool
- disconnect USBprog
- remove jumper
- plug in USBprog
Tips - The lines TX and RX can still be used in firmwares (such as USB to RS232 convertors). When starting, both lines are active as UART, which basically means you build up a null modem cable connection when setting the jumper. The bootloader sends a certain symbol and checks if it receives it again. If that's the case, the USB bootloader mode is activated.
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