You may be chasing your tail on the OTG stuff, I've the impression that OTG is related to the MK20DX.... being the host to some other USB client like device and I am not sure it will give you an interrupt you can use to wake with if it becomes a client on a USB bus mastered by the OS on a PC.
That said, I've been wrong before and that should be said too, about now, probably
I think you are looking at a field referring to a bit number in which case hexadecimal 0x80 is 0b10000000 is 128 in decimal.
I think that to cut to the chase you should probably go with the resistor dividor to get the project done to an extent in which you are ready to release to the lab sooner. I also think that an alternative I'd happily enough vote for is to make the end user press the program button after plugging the Teensy in and running the Teensy Loader on the PC.
That said, I've been wrong before and that should be said too, about now, probably
...
Also, looking at the mk20dx128.h file, those status registers are there, but they don't seem to match the manual...I assume if it is 8 bit and the field value is 7, then you use 0x07, but in that file is usually has 0x80.
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I think you are looking at a field referring to a bit number in which case hexadecimal 0x80 is 0b10000000 is 128 in decimal.
I think that to cut to the chase you should probably go with the resistor dividor to get the project done to an extent in which you are ready to release to the lab sooner. I also think that an alternative I'd happily enough vote for is to make the end user press the program button after plugging the Teensy in and running the Teensy Loader on the PC.