ESP-Hosted firmware

The Wi-Fi and BLE stack runs on the ESP32-C3 and talks to the f1c200s over SPI through ESP-Hosted. The host-side driver (esp32_spi / esp-hosted-ng) is built by Buildroot; the ESP32-C3 firmware lives under src/esp-hosted/esp_hosted_ng/esp/esp_driver/.

Rebuilding the ESP32-C3 firmware

From the repository root:

cd src/esp-hosted/esp_hosted_ng/esp/esp_driver
cmake .                          # fetches esp-idf as a submodule
cd esp-idf && . ./export.sh      # activate the ESP-IDF toolchain
cd ../network_adapter
idf.py set-target esp32-c3
idf.py build

The resulting binary is then flashed to the ESP32-C3 over its UART/USB programming interface.

Loading the host driver

The esp32_spi module is loaded at runtime against the host SPI bus. The reset GPIO and SPI clock speed are passed as module parameters:

modprobe esp32_spi resetpin=97 clockspeed=1

Once the link is up, a virtual interface appears:

ip link show espsta0
ip link set dev espsta0 up
iw espsta0 scan

espsta0 is a standard wireless netdev; configure it via iw, wpa_supplicant, or iwd as usual.