Raspberry Pi Pico W comes with a chip, CYW43439, that is capable to do WiFi and Bluetooth (both Classic and LE). According to Chapter 2.1 in Raspberry Pi Pico W:s datasheet, GPIO24, GPIO25 and GPIO29 is used to communicate with the CYW43439 chip using SPI protocol.
Chapter 4.2 in CYW43439:s datasheet describes the generic SPI protocol interface, but Chapter 4 is the WLAN System Interface documentation. The same datasheet describes in Chapter 9.2, that UART is the interface for Bluetooth Host Controller Interface, HCI.
When programming on the RP2040 microcontroller, I should use the wired GPIO pins to use SPI to interface CYW43439, but how can I access the Bluetooth HCI from this SPI protocol?
There is a pico C SDK (that I don't really understand), but I would like to understand the interface to implement a driver in a different programming language.