MK20DX256 bootloading

I am trying to design a new pcb for my project. I have nearly finished a design for the atsamd21 but was looking in to see if the MK20DX256 would be a better choice. I first looked into how you bootload these things, as people have had issues with bootloading the samd21 and i was seeing if it was easier/harder.

I couldn't find much but by looking through the datasheet (which I find rather vague and unhelpful) it says it has a JTAG to SWD port and so I thought I could flash the bootloader with the Jlink edu mini just as I planned to do with the samd21.

I was wondering if anyone has any experience with the mk20dx256 that could lend me some advice.

Any response is appreciated. Thanks in advance, Sean.

Not advice exactly, just a question. Do you have a bootloader image to load onto the device? If not, I suspect that’s where the idea will come to a screeching halt.

PJRC's Teensy 3.1 uses an mk20dx256. They use a proprietary bootloading mechanism (which I believe they sell.) I don't know how many details they've released about how it works, but I think it uses SWD (the ARM debug protocol) to load a USB-capable bootloader into RAM of the mk20, which then runs and does the actual upload (this way, no flash is consumed by the bootloader. But it does need the extra chip.)

I don't see why a conventional flash-resident bootloader wouldn't be possible, but I don't know of one that's in common use.

I'm in a similar boat with a board I designed. Using MK20DX256VLH7 and have brought out lines for the SWD with the intent of programming using a Segger J-Link.

So, why would you need a boot loader if you can program via a J-Link Mini, or is there something I'm missing?