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SDIO_setup.md

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Wi-Fi and BT/BLE connectivity Setup over SDIO

Supported Targets ESP32 ESP32-C6

1. Setup

1.1 Hardware Setup

In this setup, ESP board acts as a SDIO peripheral and provides Wi-Fi capabilities to host. Please connect ESP board to Raspberry-Pi with jumper cables as mentioned below. Raspberry Pi should be powered with correct incoming power rating. ESP can be powered through PC using micro-USB/USB-C cable.

Raspberry-Pi Pin ESP32 Pin ESP32-C6 Pin Function
13 IO13+pull-up IO23+pull-up DAT3
15 IO14 IO19 CLK
16 IO15+pull-up IO18+pull-up CMD
18 IO2+pull-up IO20+pull-up DAT0
22 IO4+pull-up IO21+pull-up DAT1
31 EN ESP Reset
37 IO12+pull-up IO22+pull-up DAT2
39 GND GND GND

Raspberry-Pi pinout can be found here!

Sample setup image of ESP32 SDIO with RPi looks like:

alt text

⚠️ Note: As SDIO faces signal integrity issues over jumper wires, we strongly recommend to Design PCB boards with above connections. If that is not possible

  • Use good quality extremely small (smaller than 5cm) jumper wires, all equal length
  • Join all possible grounds interconnected to lower noise
  • Add at least, 10k Ohm external pull-up resistors on 5 lines: CMD, DAT0-4. We use 51k Ohm resistors in our set-up.

1.2 Raspberry-Pi Software Setup

By default, the SDIO pins of Raspberry-pi are not configured and are internally used for the built-in Wi-Fi interface. Please enable SDIO pins by appending the following line to the /boot/firmware/config.txt file (prior to Bookworm, the file is at /boot/config.txt):

dtoverlay=sdio,poll_once=off
dtoverlay=disable-bt

Please reboot Raspberry-Pi after changing this file.

Note that the default Wi-Fi on your Raspberry Pi will be disabled on reboot. This is because the SDIO used in ESP-Hosted is going to use this SDIO port here on. If you are not using desktop variant of Raspberry Pi, It would be good to set up static IP SSH with ethernet cable.

Also, it is recommended to download (any) software needed (like iperf etc) before rebooting, so that losing Wi-Fi is not an issue.

2. Load ESP-Hosted Solution

2.1 Host Software

  • Execute following commands in root directory of cloned ESP-Hosted repository on Raspberry-Pi
$ cd esp_hosted_fg/host/linux/host_control/
$ ./rpi_init.sh sdio
  • This script compiles and loads host driver on Raspberry-Pi. It also creates virtual serial interface /dev/esps0 which is used as a control interface for Wi-Fi on ESP peripheral

2.2 ESP Peripheral Firmware

One can load pre-built release binaries on ESP peripheral or compile those from source. Below subsection explains both these methods.

2.2.1 Load Pre-built Release Binaries

  • Download pre-built firmware binaries from releases
  • Follow readme.txt from release tarball to flash the ESP binary
  • ⚠️ Make sure that you use Source code (zip) in Assets fold with associated release for host building.
  • Windows user can use ESP Flash Programming Tool to flash the pre-built binary.
  • Collect firmware log
    • Use minicom or any similar terminal emulator with baud rate 115200 to fetch esp side logs on UART
$ minicom -D <serial_port>

serial_port is device where ESP chipset is detected. For example, /dev/ttyUSB0

2.2.2 Source Compilation

Make sure that same code base (same git commit) is checked-out/copied at both, ESP and Host

Set-up ESP-IDF
  • Note on Windows 11: you can follow these instructions, instead of the following, to setup ESP-IDF and build the esp firmware.
  • ⚠️ Following command is dangerous. It will revert all your local changes. Stash if need to keep them.
  • Install the ESP-IDF using script
$ cd esp_hosted_fg/esp/esp_driver
$ cmake .
  • Set-Up the build environment using
$ . ./esp-idf/export.sh
# Optionally, You can add alias for this command in ~/.bashrc for later use
Configure, Build & Flash SDIO ESP firmware
  • Set slave chipset environment
$ cd network_adapter
$ rm -rf sdkconfig build
$ idf.py set-target <esp_chipset>

For SDIO, <esp_chipset> could be esp32 or esp32c6

  • Execute following command to configure the project
$ idf.py menuconfig
  • This will open project configuration window. To select SDIO transport interface, navigate to Example Configuration -> Transport layer -> SDIO interface -> select and exit from menuconfig.
  • Use below command to compile and flash the project. Replace <serial_port> with ESP peripheral's serial port.
$ idf.py -p <serial_port> build flash
  • Collect the firmware log using
$ idf.py -p <serial_port> monitor

3. Checking the Setup for SDIO

  • Firmware log On successful flashing, you should see following entry in ESP log:
[   77.877892] Features supported are:
[   77.877901]   * WLAN
[   77.877906]   * BT/BLE
[   77.877911]     - HCI over SDIO
[   77.877916]     - BT/BLE dual mode
  • Host log Once ESP peripheral has a valid firmware and booted successfully, you should be able to see successful enumeration on Raspberry Pi side as:
$ dmesg
[   14.309956] Bluetooth: Core ver 2.22
[   14.310019] NET: Registered protocol family 31
[   14.310022] Bluetooth: HCI device and connection manager initialized
[   14.310038] Bluetooth: HCI socket layer initialized
[   14.310045] Bluetooth: L2CAP socket layer initialized
[   14.310069] Bluetooth: SCO socket layer initialized
[   14.327776] Bluetooth: HCI UART driver ver 2.3
[   14.327784] Bluetooth: HCI UART protocol H4 registered
[   14.328014] Bluetooth: HCI UART protocol Three-wire (H5) registered
[   14.328138] Bluetooth: HCI UART protocol Broadcom registered
[   14.650789] Bluetooth: BNEP (Ethernet Emulation) ver 1.3
[   14.650796] Bluetooth: BNEP filters: protocol multicast
[   14.650810] Bluetooth: BNEP socket layer initialized
[   14.715079] Bluetooth: RFCOMM TTY layer initialized
[   14.715109] Bluetooth: RFCOMM socket layer initialized
[   14.715137] Bluetooth: RFCOMM ver 1.11
[   20.556381] mmc1: card 0001 removed
[   69.245969] mmc1: queuing unknown CIS tuple 0x01 (3 bytes)
[   69.253368] mmc1: queuing unknown CIS tuple 0x1a (5 bytes)
[   69.256622] mmc1: queuing unknown CIS tuple 0x1b (8 bytes)
[   69.258842] mmc1: queuing unknown CIS tuple 0x80 (1 bytes)
[   69.258939] mmc1: queuing unknown CIS tuple 0x81 (1 bytes)
[   69.259035] mmc1: queuing unknown CIS tuple 0x82 (1 bytes)
[   69.260840] mmc1: queuing unknown CIS tuple 0x80 (1 bytes)
[   69.260939] mmc1: queuing unknown CIS tuple 0x81 (1 bytes)
[   69.261040] mmc1: queuing unknown CIS tuple 0x82 (1 bytes)
[   69.261236] mmc1: new SDIO card at address 0001
[   76.892073] esp32: loading out-of-tree module taints kernel.
[   76.893083] esp32: Resetpin of Host is 6
[   76.893202] esp32: Triggering ESP reset.
[   76.894498] esp_sdio: probe of mmc1:0001:1 failed with error -110
[   76.894566] esp_sdio: probe of mmc1:0001:2 failed with error -110
[   77.596173] mmc1: card 0001 removed
[   77.649578] mmc1: queuing unknown CIS tuple 0x01 (3 bytes)
[   77.657019] mmc1: queuing unknown CIS tuple 0x1a (5 bytes)
[   77.660243] mmc1: queuing unknown CIS tuple 0x1b (8 bytes)
[   77.662448] mmc1: queuing unknown CIS tuple 0x80 (1 bytes)
[   77.662545] mmc1: queuing unknown CIS tuple 0x81 (1 bytes)
[   77.662643] mmc1: queuing unknown CIS tuple 0x82 (1 bytes)
[   77.664445] mmc1: queuing unknown CIS tuple 0x80 (1 bytes)
[   77.664541] mmc1: queuing unknown CIS tuple 0x81 (1 bytes)
[   77.664637] mmc1: queuing unknown CIS tuple 0x82 (1 bytes)
[   77.664832] mmc1: new SDIO card at address 0001
[   77.665287] esp_probe: ESP network device detected
[   77.877892] Features supported are:
[   77.877901] 	 * WLAN
[   77.877906] 	 * BT/BLE
[   77.877911] 	   - HCI over SDIO
[   77.877916] 	   - BT/BLE dual mode
[   78.096179] esp_sdio: probe of mmc1:0001:2 failed with error -22

If intended transport is SDIO+UART, please continue ahead with UART setup