Mixing UART C3 registers with C2 bit flags

[ssilverman]

TeensyDmx/TeensyDmx.cpp

Line 2286 in da868f9

UART0_C3 &= ~(UART_C3_FEIE | UART_C2_RIE | UART_C2_ILIE);

Seems to be mixing UART register C3 with register C2 bit flags; also for UARTs 1-5.