General Purpose Digital I/O that may be configured through the registers to perform various functions
including: Microcontroller Clock Output, FIFO status, POR, Wake-Up timer, Low Battery Detect, TRSW,
AntDiversity control, etc. See the SPI GPIO Configuration Registers, Address 0Bh, 0Ch, and 0Dh for .more information.

Serial Clock Input.
digital input. This pin provides the serial data clock function for the
4-line serial data bus. Data is clocked *** the RF CHIP on positive edge transitions

Serial Interface *** input. 0– VDD V digital input. This pin provides the ***/Enable function for the 4-line serial data bus. The signal is also used to signify burst read/write mode

General Microcontroller Interrupt Status output. When the Si4430/31/32 exhibits anyone of the Interrupt
Events the nIRQ pin will be set low=0. Please see the Control Logic registers section for more information
on the Interrupt Events. The Microcontroller can then determine the state of the interrupt by reading a corresponding
SPI Interrupt Status Registers, Address 03h and 04h. No external resistor pull-up is required,but it may be desirable if multiple interrupt lines are connected

Shutdown input pin. 0–VDD V digital input. SDN should be = 0 in all modes except Shutdown mode. When SDN =1 the chip will be completely shut down and the contents of the registers will be lost.