Bootloading the NCP#

The SPI Protocol supports a Payload Frame called the Bootloader Frame for communicating with the NCP when the NCP is in bootloader mode. The NCP can enter bootload mode through either an EZSP command or a recovery pin low while the NCP exits reset. In the Gecko Bootloader, a recovery pin can be defined in the board configuration to initiate bootloader mode. While nWAKE is the default for that function, it can be defined to be any valid GPIO pin. The pin definition method for the Gecko Bootloader is through BTL_GPIO_ACTIVATION_PORT/PIN/POLARITY set through the Gecko Bootloader’s "EZSP GPIO Activation" component/plugin.

Assert nRESET to hold the NCP in reset. While nRESET is asserted, assert (active low) nWAKE and then deassert nRESET to boot the NCP. Do not deassert nWAKE until the NCP asserts nHOST_INT, indicating that the NCP has fully booted and is ready to accept data over the SPI Protocol. Once nHOST_INT is asserted, nWAKE may be deasserted. Refer to UG100: EZSP Reference Manual for more information on the bootloader and the format of the Bootloader Frame.