@@ -39,98 +39,7 @@ One of the troubles with Arduino is that people forget that it is just a big C++
Indeed, in the PlatformIO environment, we even have wonderful autocomplete handles on the D51's core register map. For some examples of this kind of manipulation, check out the `hunks` in the [ponyo](https://gitlab.cba.mit.edu/squidworks/ponyo) project.
### Bare Metal development
Okay, bare-ish metal development. If you want to work with the SAMD51 using the command line, a text editor, Makefiles, and a few open-source tools, it's possible to do so with a bit of setup. You should use Linux to do this work; your mileage may vary on other operating systems.
Credit to Alex Kaspar for sorting through openocd setup in 2018. These instructions build on that work.
First, install [openocd](http://openocd.org/getting-openocd/). Until recently, this tool didn't officially support the SAMD51 series, requiring the use of a [patch](http://openocd.zylin.com/#/c/4272/) and manual compilation to work with the chipset. According to the patch notes, the patch was merged in early 2019 so the standard installation should work fine. Put the program in directory such as ~/openocd. If you're building from source, navigate to this directory and run:
```
./bootstrap
./configure --enable-cmsis-dap
make
make install
```
Second, install a handful of other helpful tools. Depending on your other work you may already have many of these on your machine:
/usr/bin/../lib/gcc/arm-none-eabi/7.3.1/../../../../arm-none-eabi/bin/ld: warning: main.o uses 32-bit enums yet the output is to use variable-size enums; use of enum values across objects may fail
/usr/bin/../lib/gcc/arm-none-eabi/7.3.1/../../../../arm-none-eabi/bin/ld: warning: samd51/startup/system_samd51.o uses 32-bit enums yet the output is to use variable-size enums; use of enum values across objects may fail
/usr/bin/../lib/gcc/arm-none-eabi/7.3.1/../../../../arm-none-eabi/bin/ld: warning: samd51/startup/startup_samd51.o uses 32-bit enums yet the output is to use variable-size enums; use of enum values across objects may fail
Errors are not uncommon and are usually related to the directory structure of the Makefile. However, this repo includes all of the required SAMD51 libraries (from Atmel/Microchip's ASF4 framework, as shared by [Adafruit](https://github.com/adafruit/asf4)), so if you grabbed the entire repo you should be fine. Post an issue if it doesn't work. Note one modification to the Makefile is that it deletes all the intermediate files (.o, .eep, etc) after producing the .elf file. If you want them, remove the lines in the Makefile after the phrase 'Deleting intermediate files...'.
Fourth, after you have your .elf file (in this case `main.elf`), connect your target board to power and an Atmel ICE programmer (make sure you use the correct pinout and the SAM port!) and run `openocd`. You should see the following:
Info : at91samd51j18.cpu: hardware has 6 breakpoints, 4 watchpoints
Info : Listening on port 3333 for gdb connections
```
If you see `Error: unable to open CMSIS-DAP device 0x3eb:0x2141`, it probably means openocd needs root privileges to access the programmer. You could run `sudo openocd`, but a better solution is to follow the instructions [here](https://forgge.github.io/theCore/guides/running-openocd-without-sudo.html) to create a new rule. Don't forget to restart `udev` after doing this with `sudo udevadm trigger`.
Fifth, now that openocd is running, open a second terminal window and type `arm-none-eabi-gdb main.elf`. When gdb opens, type `tar ext :3333` (a shortcut for `target extended-remote :3333`), then `load`. This should flash the microcontroller with the new code, at which point you can exit gdb with `quit` and `y`. In the openocd window, close the connection with `Ctrl-C`. If you're flashing one of Jake's [moduleboards](https://gitlab.cba.mit.edu/squidworks/moduleboard-atsamd51/tree/master), the red and green LEDs should blink.
/usr/bin/../lib/gcc/arm-none-eabi/7.3.1/../../../../arm-none-eabi/bin/ld: warning: main.o uses 32-bit enums yet the output is to use variable-size enums; use of enum values across objects may fail
/usr/bin/../lib/gcc/arm-none-eabi/7.3.1/../../../../arm-none-eabi/bin/ld: warning: samd51/startup/system_samd51.o uses 32-bit enums yet the output is to use variable-size enums; use of enum values across objects may fail
/usr/bin/../lib/gcc/arm-none-eabi/7.3.1/../../../../arm-none-eabi/bin/ld: warning: samd51/startup/startup_samd51.o uses 32-bit enums yet the output is to use variable-size enums; use of enum values across objects may fail
