MCR_IE
#define MCR_IENABLE MCR_IE
uart_setreg(bas, REG_MCR, MCR_IE | MCR_RTS | MCR_DTR);
uart_setreg(bas, REG_MCR, MCR_IE);
mcr = MCR_IE;
uart_setreg(bas, REG_MCR, MCR_LOOPBACK | MCR_IE | MCR_DTR | MCR_RTS);