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Ivan Moreno
Ivan Moreno

Posted on • Updated on

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

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