Mainboard as CAN interface instructions.

[kingjamez]

In the instructions for mainboard flashing, it first has the first step as flashing Katapult onto the mainboard, then flashing Klipper once Katapult is loaded. This seems like an unnecessary step.

Why not just flash klipper directly?

I've tested the Octopus Pro V1.0 as a USB CAN Bridge by flashing Klipper directly to the board without Katapult. Everything works perfectly.

It would also be helpful for folks with the Octopus Pro V1.0 to know that at least on some versions of the board, it does not go into DFU mode. If you want to flash that board, no amount of reset buttons, jumpers, or any other combo (even after flashing katapult or klipper) will get it into DFU mode. The SD Card (with a file named firmware.bin) is the only way to do it.

[Esoterical]

If you are using USB-CAN-Bridge mode but aren't using katapult, then there is no way to autmoatically update klipper simply via an SSH session. You would need to either leave the stock bootloader on the octopus and update via SD card,or you would need to put the octopus into DFU mode each time.

As for "Octo pro 1.0 doesn't go into DFU mode", it sure does. As a general rule anyway. THere have been instances where specific boards won't go into DFU mode (usually due to dodgy boot/reset buttons).
And even if I had an octo pro that wouldn't go into DFU mode, then I would be doubly certain to put katapult on there by using the katapult "deployment mode" deployer.bin onto the SD card and let it overwrite the stock bootloader.

But if you prefer the harder way, go nuts. You are 100% correct that it will still work perfectly fine without katapult. Which is why I have that note on the first page of the guide

Katapult is really handy but it is NOT mandatory. This will be discussed later, but Klipper will happily run over a CAN network with or without Katapult.