EZSP-SPI Protocol#

The SPI protocol refers to the unique framing behavior of the SPI implementation of EZSP as opposed to UART. The EZSP protocol refers to the framing of EZSP-related commands and responses, which are encapsulated by certain SPI frames in the SPI protocol. The EZSP-SPI Protocol uses a 4-wire SPI interface to communicate between the host processor and NCP, plus an additional pair of GPIOs for handshake signaling in each direction.

  • To the Host the NCP looks like a hardware peripheral.

  • The NCP is the slave device and all transactions are initiated by the Host.

  • The SPI interface supports a reasonably high data rate.

This document describes the current protocol versions:

  • SPI Protocol version 0X82 (defined by SPIP_VERSION in spi-protocol.h;)

  • EZSP protocol version 0xE (defined by EZSP_PROTOCOL_VERSION in ezsp-protocol.h;7.4)