I'm interested to know if the FRDM-KL82Z can be powered from a 3.3V source, without powering up the onboard OpenSDA circuit. Has anyone had any experience doing this?
Looking at the schematic it seems like it should work. However, I've been bitten by this kind of thing before.
Any help appreciated.
As a quick suggestion, you can power the board MCU using the coil cell battery input, which has a voltage range from 2 to 3.6V. With this power supply mode, the Open SDA it is not operational.
Please take a look at the FRDM-KL82Z user guide chapter 3.1.Power supply to gather further details on the required jumper settings and other power supply modes https://www.nxp.com/docs/en/user-guide/FRDMKL82ZUG.pdf
When the Open SDA it is not operational, I will recommend changing the board J23 from 1,2 to 2,3. this will bypass the reset button directly, instead using the on board reset IC. Please, check the reset circuit in the schematic.
If I can help further please, let me know!