MSP432用户手册

MSP432 低功耗高性能并存10.1 Digital I/O Introduction The digital I/O features include: • Independently programmable individual I/Os • Any combination of input or output • Individually configurable interrupts for ports (available for certain ports only) • Independent input and output data registers • Individually configurable pullup or pulldown resistors • Wake-up capability from ultra-low power modes (available for certain ports only) • Individually configurable high drive I/Os (available for certain I/Os only) Devices within the family may have up to eleven digital I/O ports implemented (P1 to P10 and PJ). Most ports contain eight I/O lines; however, some ports may contain less (see the device-specific data sheet for ports available). Each I/O line is individually configurable for input or output direction, and each can be individually read or written. Each I/O line is individually configurable for pullup or pulldown resistors. Certain ports have interrupt and wake-up capability from ultra-low power modes (see device specific data sheet for ports with interrupt and wake-up capability). Each interrupt can be individually enabled and configured to provide an interrupt on a rising or falling edge of an input signal. All interrupts are fed into an encoded Interrupt Vector register, allowing the application to determine which sub-pin of a port has generated the event. Individual ports can be accessed as byte-wide ports or can be combined into half-word-wide ports. Port pairs P1 and P2, P3 and P4, P5 and P6, P7 and P8, and so on, are associated with the names PA, PB, PC, PD, and so on, respectively. All port registers are handled in this manner with this naming convention. The main exception are the interrupt vector registers, for example, interrupts for ports P1 and P2 must be handled through P1IV and P2IV, PAIV does not exist. When writing to port PA with half-word operations, all 16 bits are written to the port. When writing to the lower byte of port PA using byte operations, the upper byte remains unchanged. Similarly, writing to the upper byte of port PA using byte instructions leaves the lower byte unchanged. When writing to a port that contains less than the maximum number of bits possible, the unused bits are don't care. Ports PB, PC, PD, PE, and PF behave similarly.