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Getting_started.md

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Getting started with Raspberry-Pi (rpi)

Wi-Fi Connectivity

host_commands python module in host/linux/host_control directory implements the communication protocol between the host and ESP32. It contains following functions which can be used to control Wi-Fi functionality of the ESP32 as follows:

Function Functionality
wifi_get_mac(mode) get MAC address of station or softAP Interface
wifi_get_mode() get wifi mode
wifi_set_mode(mode) set wifi mode
wifi_set_ap_config(ssid, pwd, bssid, is_wpa3_supported, listen_interval) connect to AP as a station
wifi_get_ap_config() get AP configuration and status
wifi_disconnect_ap() disconnect from AP
wifi_set_softap_config(ssid, pwd, chnl, ecn, max_conn, ssid_hidden, bw) start softAP
wifi_get_softap_config() get softAP configuration
wifi_ap_scan_list() scan available APs
wifi_connected_stations_list() list stations connected to softAP
wifi_set_mac(mode, mac) sets custom mac address for station and softAP Interface
wifi_set_power_save_mode(power_save_mode) set power save mode
wifi_get_power_save_mode() get power save mode

These python functions can be used to control Wi-Fi functionality of the ESP32. Also see host/linux/host_control/test.py script for an example of using these functions. You can run the script as follows:

python test.py

To compile and load the host driver on a Raspberry Pi, go to host/linux/host_control/ folder and run ./rpi_init.sh <sdio/spi>. This script also creates /dev/esps0 device, which is used as a WLAN control interface.

The other scripts in the same directory can be used to:

  • connect to AP as a station
  • disconnect from AP
  • start softAP
  • stop softAP
  • scan available APs
  • list stations connected to softAP
  1. station_connect.py is a python script which configures ESP32 in station mode, and connects to an external AP with user-provided credentials. Also it enables the station interface and runs DHCP client. The script accepts arguments such as SSID, password, optionally MAC address, wpa3 support and listen interval (AP beacon intervals). For example:
python station_connect.py 'xyz' 'xyz123456' --bssid='e5:6c:67:3c:cf:65' --is_wpa3_supported=True --listen_interval=3

You can check that ethsta0 interface is up (enabled) using ifconfig. WPA3 option is only applicable if target AP supports WPA3.

To know status of station, use wifi_get_ap_config() function. In case station is connected with AP, it returns ssid, bssid(MAC address), channel, rssi, encryption mode of AP. and In case of not connected with AP returns failure with not_connected print.

  1. station_disconnect.py is a python script to disconnect ESP32 station from AP.
python station_disconnect.py

You can check that ethsta0 interface is down (disabled) using ifconfig.

  1. softap_config.py is a python script for configuring ESP32 to work in softAP mode. The following parameters should be provided:
  • SSID
  • password, should be 8 ~ 64 bytes ASCII
  • channel ID, 1 ~ 11
  • encryption method (0: OPEN, 2: WPA_PSK, 3: WPA2_PSK, 4: WPA_WPA2_PSK)
  • maximum number of stations, in range of 1 ~ 10.
  • whether SSID is hidden (1 if the softAP shouldn't broadcast its SSID, else 0)
  • bandwidth (1: WIFI_BW_HT20 (20MHZ), 2: WIFI_BW_HT40 (40MHZ))

The maximum number of connections, "SSID hidden", and bandwidth parameters are optional.

For example:

python softap_config.py 'xyz' 'xyz123456' 1 3 --max_conn=4 --ssid_hidden=0 --bw=1

You can check that ethap0 interface is up (enabled) using ifconfig. Note: Currently WEP, WPA2_ENTERPRISE, WPA3 support is not present for ESP32 softAP mode.

To start data connection, set up a DHCP server on the Raspberry Pi, or configure a static IP address for AP interface (ethap0).

  1. softap_stop.py is a python script to disable ESP32 softAP mode. This script will change wifi mode to null if only softAP is running, or to station mode if softAP and station both are on.
python softap_stop.py

You can check that ethap0 interface is down (disabled) using ifconfig.

  1. ap_scan_list.py is a python script which gives a scanned list of available APs. The list contains SSID, channel number, RSSI, MAC address, and authentication mode of AP.
python ap_scan_list.py
  1. connected_stations_list.py is a python script that returns a list of MAC addresses of stations connected to softAP.
python connected_stations_list.py

Open air throughput test results for WLAN on SDIO Interface

Following are the test results conducted in open air.

UDP Tx: 16.4 Mbps
UDP Rx: 16.8 Mbps
TCP Tx: 14 Mbps
TCP Rx: 12 Mbps

For Bluetooth/BLE functionality

  • Ensure that bluez is installed on Raspberry Pi and it is downloaded in source format as well. Please refer to Setup instructions for more details.
  • In following test, Android device was used as a BT/BLE test device. For BLE testing, nRF connect for mobile APP was used.
  • Go to host/linux/host_control/ folder to run following script.

UART based setup

  1. Execute ./rpi_init.sh btuart to prepare Raspberry Pi for Bluetooth operation
  2. Execute hciattach command as below to add HCI interface (i.e. hciX)
$ sudo hciattach -s 115200 /dev/serial0 any 115200 flow

SDIO based setup

Execute ./rpi_init.sh or ./rpi_init.sh sdio to prepare Raspberry-Pi for SDIO+BT operation. HCI interface (i.e hciX) will be available for use as soon as host driver detects ESP32 module over SDIO interface. You can use standard HCI utilities over this interface to make use of BT/BLE feature.

SPI based setup

Execute ./rpi_init.sh spi to prepare Raspberry-Pi for SPI+BT operation. HCI interface (i.e hciX) will be available for use as soon as host driver detects ESP32 module over SPI interface. You can use standard HCI utilities over this interface to make use of BT/BLE feature.

Reset Pin Configuration

This is optional configuration to change the host GPIO pin used to reset ESP32. As mentioned in hardware Setup, host uses BCM 6 (Pin31) which is default value. User can change the GPIO in BCM format. Execute ./rpi_init.sh resetpin=5 to use BCM 5 (pin 29)

BT/BLE Test procedure

GATT server

  1. run hciconfig. Output should show only one SDIO interface.
hci0:	Type: Primary  Bus: SDIO
	BD Address: 3C:71:BF:9A:C2:46  ACL MTU: 1021:9  SCO MTU: 255:4
	UP RUNNING PSCAN
	RX bytes:8801 acl:1000 sco:0 events:406 errors:0
	TX bytes:5097 acl:147 sco:0 commands:52 errors:0

  1. Go to bluez-5.xx folder. Run ./test/example-gatt-server. This will start GATT server on Raspberry-Pi.

  2. Now start advertising. Run sudo hciconfig hci0 leadv.

  3. Now ESP32's mac address should be listed in scan list of mobile app.

  4. Connect to ESP32's mac address with mobile as GATT client.

  5. Check read/write characteristics fields in Heart Rate service.

GATT Client

  1. Run ./test/example-gatt-client on Raspberry Pi. This will start GATT client on Raspberry Pi.

  2. You should see a Heart Rate Measurement field in Raspberry Pi console.

BT scan

Run hcitool scan for BT device scanning.

BLE scan

Run hcitool lescan for BLE device scanning.