I'm attempting to being up a UART in MCUexpresso SDK 2.4 on an MK22FN part in interrupt mode (upper layers to deal with unexpected reception of packets from a peripheral).
This device (UART 0) is getting initialized as part of the regular BOARD_InitPeripherals() but I've turned off turning on the interrupts as I've got a bunch of setup to do prior to getting any ISRs. TX watermark is set to 0; RX watermark is set to 1 so as to get ISR for each char in and out.
As soon as I turn interrupts on (NVIC_SetPriority() followed by EnableIRQ()) for the UART I get a RX_TX (not error) ISR and it is constant. Lines in and out look normal and idle.
Inside the ISR I grab the status with UART_GetStatusFlags() and it returns 0xC00000C00 which is pretty much what I'd expect given that there is nothing in the UART at that point far as I know (in or out).
The problem is that I return out of the ISR and get another one just as soon as I get out. I can't figure out how to get the UART to stop giving me ISRs here.
I don't have problems on this part using KDS and PEX versions of this. I've looked through that code and don't see anything I'm missing here far as I can figure. Adding the demo code from ...\driver_examples\uart\interruptuart_interrupt.c to this project, it acts the same way.
Any ideas? I'm out of them myself...