This network coprocessor (NCP) application supports communication with a host application over a SPI interface. This NCP application can be built as configured, or optionally can be augmented with customizations for target hardware, initialization, main loop processing, event definition/handling, and messaging with the host. As configured, this NCP SPI application is the basis for building the corresponding binary ncp-spi images delivered with the Silicon Labs Zigbee stack. Refer to the Silicon Labs Zigbee documentation for more information about NCP customization.