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How to setup WiFi hotspot in raspberry pi and connect with ESP8266

ivanmoreno

Iván Moreno

Posted on August 14, 2020

How to setup WiFi hotspot in raspberry pi and connect with ESP8266

Basic connection between arduino and raspberry pi through WiFi

test-hw

The Hardware is

  • Esp8266 with arduino sdk
  • Raspberry pi 3b+

System requirements

  • arduino-cli
  • picocom
  • python3

Configurations for Raspberry Pi

  • Install raspbian
  • Enable ssh server
  • Upgrade system
  • Configure keys for ssh server
  • Configure the raspberry pi as hotspot
  • Install python3 and set as default python interpreter
  • Copy server code

Configurations for ESP8266

  • Install esp8266 for arduino
  • Copy the code and upload to esp8266 board

Raspberry Pi Setup

Download raspbian buster lite from official repository

$ curl -LO http://downloads.raspberrypi.org/raspbian_lite/images/raspbian_lite-2020-02-14/2020-02-13-raspbian-buster-lite.zip
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Write to sd card

$ unzip -p 2020-02-13-raspbian-buster-lite.zip | sudo dd of=/dev/mmcblk0 status=progress
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Connect the raspberry pi via Ethernet and HDMI, startup the system and access with user=pi and password=raspberry. Enable ssh service

$ sudo systemctl enable --now ssh
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Check what is the ip address and logout from the system

$ ip addr show eth0 # copy ip address
$ exit
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Connect via ssh

$ ssh pi@{ip_address}
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Add user with the same privileges and groups to pi user, generate password and delete the pi user

$ sudo useradd -m -s /bin/bash --groups $(groups pi | cut -d ' ' -f 4- --output-delimiter ',') new-user
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Create password to new-user

$ sudo passwd new-user
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Add new-user to sudoers file

$ echo "new-user ALL=(ALL) NOPASSWD: ALL" | sudo tee /etc/sudoers.d/010_new-user-nopasswd
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Login to new user

$ su new-user
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Check if sudo works

$ sudo apt update
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Check groups

$ groups new-user
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If everything works, logout and access to new-user with ssh, first logout

$ exit
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Generate keys to new-user and copy to raspberry pi

$ ssh-keygen -f ~/.ssh/rpi-key
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Copy public key to raspberry pi

$ ssh-copy-id -i ~/.ssh/rpi-key.pub new-user@{raspberry-pi-ip}
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Now access to new-user on raspberry pi

$ ssh new-user@{raspberry-pi-ip}
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Remove pi user

$ sudo userdel -rf pi
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Update and upgrade the system

$ sudo apt update && sudo apt upgrade -y
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Reboot the system

$ sudo reboot
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Setup hotspot 

Create an access point in raspberry pi

 Diagram                                  +- RPi ---------+
                                      +---+ 192.168.10.15 |          +- ESP8266 ---+
                                      |   |     WLAN AP   +-)))  (((-+ WLAN Client |
                                      |   | 192.168.7.1   |          | 192.168.7.x |
                                      |   +---------------+          +-------------+
                                      .
                                      .
                              .
                 +- Router -----+     |
                 | Firewall     |     |   +- PC#2 --------+
(Internet)---WAN-+ DHCP server  +-LAN-+---+ 192.168.10.11 |
                 | 192.168.10.1 |     |   +---------------+
                 +--------------+     |
                                      |   +- PC#1 --------+
                                      +---+ 192.168.10.10 |
                                          +---------------+
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Install required packages

$ sudo apt-get -y install hostapd dnsmasq netfilter-persistent iptables-persistent
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Enable wireless access point

$ sudo systemctl unmask hostapd
$ sudo systemctl enable hostapd
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Define the wireless interface IP configuration
Configure wlan0 interface in /etc/dhcpcd.conf
Add the following lines

  interface wlan0
    static ip_address=192.168.7.1/24
    nohook wpa_supplicant
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Enable ip forwarding in /etc/sysctl.conf and uncomment the following line

 net.ipv4.ip_forward=1
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Allow traffic between clients on this foreign wireless network

$ sudo iptables -t nat -A POSTROUTING -o eth0 -j MASQUERADE
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Make persistent changes

$ sudo netfilter-persistent save
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Configure the DHCP and DNS services for the wireless network
First create a backup

$ sudo mv /etc/dnsmasq.conf /etc/dnsmasq.conf.orig
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Edit /etc/dnsmasq.conf and add the following lines

  interface=wlan0 
  dhcp-range=192.168.7.2,192.168.7.40,255.255.255.0,24h
  domain=wlan
  address=/gw.wlan/192.168.7.1
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Set WiFi country
Localization Options -> Change WLAN Country -> choose your country -> finish

$ sudo raspi-config
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Ensure wireless operation

$ sudo rfkill unblock wlan
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Configure access point in /etc/hostapd/hostapd.conf
Add the following lines

  country_code=MX
  interface=wlan0
  ssid=rpi-hotspot
  hw_mode=g
  channel=8
  macaddr_acl=0
  auth_algs=1
  ignore_broadcast_ssid=0
  wpa=2
  wpa_passphrase=rasp-p@s2w0rd
  wpa_key_mgmt=WPA-PSK
  wpa_pairwise=TKIP
  rsn_pairwise=CCMP
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Reboot the system and check connection with new access point

Install python3 and set as default interpreter

$ sudo apt install -y python3
$ sudo rm /usr/bin/python
$ sudo ln -s /usr/bin/python3 /usr/bin/python
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Copy pythonServer to raspberry pi

ESP8266 Configurations

Install required packages

  • arduino-cli
  • picocom

Install esp8266 arduino core
First add additional boards in ~/Arduino/arduino-cli.yml and add the following lines

# arduino-cli.yaml
board_manager:
  additional_urls:
    - http://arduino.esp8266.com/stable/package_esp8266com_index.json
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Update index

$ arduino-cli --config-file ~/Arduino/arduino-cli.yml core update-index
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Search esp8266 boards

$ arduino-cli --config-file ~/Arduino/arduino-cli.yml core search esp8266
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Install esp8266 boards

$ arduino-cli --config-file ~/Arduino/arduino-cli.yml core install esp8266:esp8266
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Compile and upload the sketch, assuming that port of esp8266 is /dev/ttyUSB0

$ arduino-cli compile -b esp8266:esp8266:nodemcuv2 -u -p /dev/ttyUSB0 arduinoClient/
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Test communications

testGift

Init server in raspberry pi

$ python ~/pythonServer/server.py
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Init serial monitor for esp8266 board

$ picocom -b 115200 /dev/ttyUSB0
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Raspberry pi output 

  Intialize socket server, listen port: 35000
  Connection from: ('192.168.7.17', 59552)
  From connected user: Init connection from ESP8266
  Write response -> hi from server
  From connected user: hi from client
  Write response -> send quit sequence
  Recive disconnect from client
  Close connection...
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Arduino output 

  Wait for WiFi... .....
  WiFi connected
  IP address:
  192.168.7.17
  Connecting to 192.168.7.1:35000
  Wait response from server ...
  Server response: hi from server
  You response -> hi from client
  Server response: send quit sequence
  You response -> quit!
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Source Code

💖 💪 🙅 🚩
ivanmoreno
Iván Moreno

Posted on August 14, 2020

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