loop=normal, rts=deasserted, dtr=deasserted, function=UART, afce=disabled
UART Modem Control Register
| dtr | Data Terminal Ready 0 (deasserted): undefined 1 (asserted): undefined |
| rts | Request to Send 0 (deasserted): undefined 1 (asserted): undefined |
| loop | Loop Back Mode 0 (normal): undefined 1 (loop_back): undefined |
| afce | Auto Flow Control Enable 0 (disabled): undefined 1 (enabled): undefined |
| function | UART Function: Select IrDA or RS485 0 (UART): undefined 1 (IrDA_SIR): undefined 2 (RS485): undefined 3 (reserved): undefined |