I did buy one of these cheap all in one microcontroller, but instead of using a standard Atmel, like the ones on the Arduino boards, it uses a more powerful ARM M0 chip.
Now, I would like to buy my own M0 (picking a SAMD21G18) and make my own board, exposing only the pin that I need, but I can't find info about a critical piece of info: How do you program the chip?
The board that I did purchase, has a USB to serial chip, I believe; and it has a rom with a bootloader, so when it is in a state, you can put code on it, while when in regular state, it execute the program.
I would like to do something similar, adding a USB to serial so I can upload firmware updates if needed; but I am not sure...could I program the chips in a different way, and save on the hassle to even put a serial to USB converter?
Also is there a standard bootloader that many arduino clones use? They all seems to work in the same way, with ARduino IDE; at least to my eyes.
Hope the question is clear enough; this is my first attempt at making a breakout board from scratch. Thanks.
Found this post which has some relevant info
This person made a minimalist board with a SAM D21G18 chip; it show the finished product, some videos and schematics, so it is a good starting point.
From my findings, the chip has already the USB functionality, to upload on the ROM the code, but you need to use the Atmel own IDE. Still looking for details, but it is a good start.
Since nobody replied; I assume that nobody was aware of this link, so it may be useful to others.