Hi Everyone,

So I'm relatively new to ARM uCs. I've played with lots of mbed boards, AVRs and PICs. Although now I'm trying to get more professional in my hobbyist life haha.

So I'm trying to flash a bootloader to a ATSAMD21G18 through my Segger J-Link EDU. I'm using Atmel Studio (also tried J-Flash Lite) and everything works perfectly... Until i un-plug the j-link. This also happened on a development I was playing with (4357-evb), but at the time I did not care, as I was just playing around.


While the J-Link is still plugged in my bootloader works fine. A have my LED flashing, telling me that the program is working fine. But when I un-plug the j-link everything stops works (as if the flash was empty).


I'm sure I'm doing something wrong. Is there something extra I have to buy, to be able to physically write to the uC internal flash?


Thanks Everyone,

Sam

Hi,

I'm powering the board by an external power supply (commoned to the J-Link common).

From the screen shot attached and as far as I can see I'm programming to flash not ram (how can i double check?). I've tried your J-Flash lite program and same results.

Any idea where to go next?

I basically want the program / bootload to remain on the uC after the jtag is disconnected.



Sam

So further to the above.

I have removed the reset pin from the J-Link connector and now when I unplug the J-Link the board continues to work.

But when I turn the power to the board off and then on again the board stops working again (like the flash is empty).

This says to me that its as if the J-Link is programming the RAM and not the Flash.

Any suggestions on how I can test/fix this?

Sam