desklock/firmware/components/esp_hosted/slave/README.md

ESP-Hosted-MCU Slave example

This document details the ESP-Hosted MCU Slave Example, demonstrating the slave firmware that provides Wi-Fi and Bluetooth connectivity to host MCUs via ESP32 series co-processors.

Overview

The slave firmware enables host MCUs to utilize the Wi-Fi and Bluetooth capabilities of ESP32 series chips through SDIO, SPI, or UART interfaces. This minimal example focuses on basic connectivity; however, advanced features like Network Split and Host Power Save can be optionally configured for optimized network traffic and power management.

Supported Co-processors and Transports

The following table summarizes the supported co-processors and transport communication buses between the slave and host. This example specifically utilizes SDIO as the transport and ESP32-C6 as the slave co-processor.

Transport Supported	SDIO	SPI Full-Duplex	SPI Half-Duplex	UART
Co-Processors Supported
ESP32	✓	✓	×	✓
ESP32-C2	×	✓	✓	✓
ESP32-C3	×	✓	✓	✓
ESP32-C5	✓	✓	✓	✓
ESP32-C6/C61	✓	✓	✓	✓
ESP32-S2	×	✓	✓	✓
ESP32-S3	×	✓	✓	✓

Example Hardware Connections

This example uses the SDIO interface. The default SDIO pin connections for the ESP32-C6 slave are as follows:

SDIO Interface (Default for ESP32-P4-Function-EV-Board)

Signal	GPIO	Notes
CLK	19	Clock
CMD	18	Command
D0	20	Data 0
D1	21	Data 1
D2	22	Data 2
D3	23	Data 3
Reset	EN	Reset input

For detailed SDIO hardware connection requirements, refer to the official documentation at https://github.com/espressif/esp-hosted-mcu/blob/main/docs/sdio.md#3-hardware-considerations. The GPIO pins and transport can be configured as explained in later sections.

Quick Start Guide

1. Obtain the Slave Example

Execute the following commands to retrieve the slave example:

idf.py create-project-from-example "espressif/esp_hosted:slave"
cd slave

2. Set Up ESP-IDF

It is presumed that ESP-IDF has already been set up. If not, please proceed with the setup using one of the following options:

Option 1: Installer Way

• Windows

  • Install and set up ESP-IDF on Windows as documented in the Standard Setup of Toolchain for Windows.
  • Use the ESP-IDF Powershell Command Prompt for subsequent commands.

• Linux or macOS

  • For bash:

    bash docs/setup_esp_idf__latest_stable__linux_macos.sh
    

  • For fish:

    fish docs/setup_esp_idf__latest_stable__linux_macos.fish
    

Option 2: Manual Way

Please follow the ESP-IDF Get Started Guide for manual installation.

3. Set Target

Set the target co-processor using the command below:

idf.py set-target esp32c6

Tip

You can customize the target co-processor by replacing esp32c6 with your desired ESP32 series chip.

4. Customizing Configuration: Transport and Features

This is optional step. By default, SDIO transport is pre-configured.

You can access the configuration menu to choose desired configuration and features using:

idf.py menuconfig

The default configuration tree looks like this:

Example Configuration
└── Bus Config in between Host and Co-processor
    └── Transport layer
        └── Select transport: SDIO/SPI-Full-Duplex/SPI-Half-Duplex/UART
    └── <Other optional features>

Tip

You can optionally customize the transport layer (SDIO, SPI Full-Duplex, SPI Half-Duplex, or UART), their GPIOs in use and other optional features within this menu.

5. Build and Flash

Build and flash the firmware to your device using the commands below, replacing <SERIAL_PORT> with your device's serial port:

idf.py build
idf.py -p <SERIAL_PORT> flash monitor

Tip

You can customize the serial port (<SERIAL_PORT>) to match your specific hardware connection.

References

• ESP-Hosted MCU Documentation
• ESP32-P4-Function-EV-Board Setup
• Transport Layer Documentation
• Troubleshooting Guide