I am going to flash Makerbase THR42 board with katapult and then with Klipper. The board will be connected via CAN.
I am currently a bit confused with deployer app thing in the Katapult’s readme. I read this section multiple times, but still can’t get what is this for.
If the katapult itself is a bootloader, then what the deployer app is?
Do I need to build it for THR42 board based on RP2040 and connected via CAN?
Katapult builds to a katapult.uf2 file, while the deployer app is just .bin. How do I flash it?
A bootloader is a software program that runs when the chip first starts up. The bootloader needs to be written to a specific address in the flash chip. Katapult is a software bootloader.
Writing the bootloader to its required location in flash can be a challenge though. On some boards it requires special hardware and requires connecting lots of wires to the chip.
However, many boards already have a software bootloader (often not Katapult) that can write programs to flash. We can use this capability to make it easier to flash Katapult itself. The deployer is a software program (it is not a bootloader). The deployer can be written to flash as a regular application, written using the existing bootloader, and when the deployer runs it writes Katapult to the specific area in flash that Katapult needs to reside at. After this is done, the chip will then have Katapult as its bootloader. The main benefit of this deployer application is that one can often use it to flash Katapult without special hardware and without having to connect up lots of wires to some boards.
As for your “THR42” board - alas, I don’t know what settings you need or whether it makes sense to use Katapult or a deployer.
Thank you for the explanation. Now I understand I do not need the deployer for the THR42 board, as I can directly flash katapult to the board using built-in USB bootloader.
In fact my board now has 2 bootloaders - one built-in USB MSC one, and on top of it katapult (and on top of both the klipper firmware). To enter first bootloader I need to press BOOT and RESET, for the katapult I can use double RESET, or (if present) klipper firmware programmatically can enter katapult when receiving respective command via CAN.