Peripherals—IP2022 User’s Manual 236 www.ubicom.com Figure    4-1    shows    the    internal    hardware    structure    and
configuration registers for each pin of a port. Figure 4-1  Port Pin Block Diagram 4.1.1 Port B Interrupts Any of the 8 Port B pins can be configured as an external interrupt
input. Logic on these inputs can be programmed to sense rising or
falling edges. When an edge is detected, the interrupt flag for the
port pin is set. The recommended initialization sequence is: 515-030.eps Port Pin   RxDIR
Register RxIN Register
(SYNC bit set) 0 = Output
1 = Hi-Z Input  RxOUT
Register Synchronization Register   RxIN Register
(SYNC bit clear)