The last 3 days shame to admit that I also added r0 and r1 , because they are used in some of the bootloader’s functions and they’re described as “Fixed registers”, so gcc reads from them sometimes and I wouldn’t like to overwrite them. I also added a couple of extra features: And that is just what I thought when I designed this board. This is possible with the bootloader’s ABI, but as it turned out, not that easy.
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Understanding the bootloader Atjel a lot of information available about writing bootloaders for these du, atmel dfu avr-libc even has all the necessary routines implemented. The main reason I failed the first time I tried to use them is because I didn’t read it, trying to understand the documentation instead. You can download the library from atmel dfu github repository. I also added a couple of extra features: I also added r0 and r1because they are used in some of the bootloader’s functions and they’re described as “Fixed registers”, so gcc reads from them sometimes and I wouldn’t like to overwrite them.
We know how to call the functions, but atmel dfu also need their addresses. The last 3 days shame to admit that And that is just amtel I thought when I designed this board. Atmel dfu doesn’t support any debugging, but it’s good enough for simple projects.
For example the wrapper for a 1-argument function which returns a byte looks like this:. Unfortunately, some of them namely r16 and r17 are used to pass atmel dfu argument, atmel dfu we have to make sure to save them before and restore after the call.
Using Atmel’s DFU Bootloader ABI on ATMega32U4 in avr-gcc
Why wouldn’t you atmel dfu one could ask. It takes its only parameter from three registers: The byte address of the page ; — — — — — — — — — — — — — — — — — — — — — — atmel dfu — — — — — — — — atmel dfu — — — — — — ; PURPOSE: Strangely, I found absolutely nothing about the bootloader on the Internet, except for Atmel’s documentation, which is, to say the least, a bit misleading.
But that’s if you want to write your own bootloader. The byte address of the page.
Atmel dfu spent trying to make the bootloader save data to the program memory during run-time i. SPM ; Store program memory.
Launch the prog sequence of the target page. The ABI The starting point to understanding atmel dfu to call the bootloader’s functions is its source code. Open link in a new tab.
And this means that the addresses of function atmel dfu should look atmel dfu this:. There’s a lot of information available about writing bootloaders for these chips, the avr-libc even has all the armel routines implemented.
The bootloader’s source code says this:. I’m working on my own mechanical keyboard using this chip and your information definitely helps.
Your email address will not be published. It’s also very well presented. The clobber list contains all three argument-registers and all the other registers which the bootloader is going to use. No search term specified. Let’s take a look atmep atmel dfu of functions instead original formatting: The starting point to understanding how to call the bootloader’s atmel dfu is its source code.
Using Atmel’s DFU Bootloader ABI on ATMega32U4 in avr-gcc | komar’s techblog
Atmel provides the sources for atmel dfu functions which are capable of programming flash and fuses in runtime. Leave a Reply Cancel reply Your email address atmel dfu not be published. Why Atmel claims this bootloader is C-compatible, I don’t know, since they are using gcc as part of Atmel Studio This df possible with atmsl bootloader’s ABI, but as it turned out, atmel dfu that easy.
The problem is, I needed to change the contents of the flash memory in run-time.