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

4 min readOct 13, 2020

In this tutorial, we will configure a raspberry pi as an access point to connect to the esp8266 WiFi board using the arduino SDK and a python script.

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 raspberry os lite from official repository

$ curl -LO https://downloads.raspberrypi.org/raspios_lite_armhf/images/raspios_lite_armhf-2020-08-24/2020-08-20-raspios-buster-armhf-lite.zip

Write to sd card, in linux with dd command

$ unzip -p 2020-08-20-raspios-buster-armhf-lite.zip | sudo dd of=/dev/mmcblk0 status=progress

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

Check what is the ip address and logout

$ ip addr show eth0 # copy ip address
$ exit

Connect remotely via ssh

$ ssh pi@{ip_address}

Add user with the same privileges and groups to pi user, generate password and delete pi user

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

Create password to new-user

$ sudo passwd new-user

Add new-user to sudoers file

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

$ su new-user

Check if sudo works

$ sudo apt update

Check groups

$ groups new-user

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

$ exit

Generate keys to new-user and copy to raspberry pi

$ ssh-keygen -f ~/.ssh/rpi-key

Copy public key to raspberry pi

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

Now access to new-user on raspberry pi

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

Remove pi user

$ sudo userdel -rf pi

Update and upgrade the system

$ sudo apt update && sudo apt upgrade -y

Reboot the system

$ sudo reboot

Setup hotspot

Install required packages

$ sudo apt-get -y install hostapd dnsmasq netfilter-persistent iptables-persistent

Enable wireless access point

$ sudo systemctl unmask hostapd
$ sudo systemctl enable hostapd

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

Enable ip forwarding in /etc/sysctl.conf and uncomment the following line

net.ipv4.ip_forward=1

Allow traffic between clients on this foreign wireless network

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

Make persistent changes

$ sudo netfilter-persistent save

Configure the DHCP and DNS services for the wireless network
First create a backup

$ sudo mv /etc/dnsmasq.conf /etc/dnsmasq.conf.orig

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

Set WiFi country
Localization Options -> Change WLAN Country -> choose your country -> finish

$ sudo raspi-config

Ensure wireless operation

$ sudo rfkill unblock wlan

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

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

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

Update index

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

Search esp8266 boards

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

Install esp8266 boards

$ arduino-cli --config-file ~/Arduino/arduino-cli.yml core install esp8266:esp8266

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/

Test communications

Init server in raspberry pi

$ python ~/pythonServer/server.py

Init serial monitor for esp8266 board

$ picocom -b 115200 /dev/ttyUSB0

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...

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!

Source code