The MK22DX256VLF5 reference manual states that all of the UARTs have AMR support. It doesn't define AMR, and no further mention is made of this. Does anyone know what this is?
My best guess is that it's a reference to automatic meter reading, and maybe a protocol like IEC 61107, but I don't see anything else in the documentation to support that.
Searching NXP.com brings up information on anisotropic magnetoresistive angular position sensors, and the GSM adaptive multi-rate codec. Neither of those have anything to do with UARTs.