Chapter 20:

PAGING SYSTEM

Implementing a Raspberry Pi-Based Paging System

Introduction

This guide details how to set up a Wi-Fi paging system using a Raspberry Pi. It enables patients to notify nursing staff with a simple button press on a web page. The press activates a Raspberry Pi pin, signaling via an LED or buzzer.

System Setup

1. Software Installation:

   • Begin by installing necessary software:

     sudo apt install git

     sudo apt install apache2 -y

     sudo apt-get install php libapache2-mod-php -y

   • Install WiringPi for GPIO control:

     sudo clone git://git.dragon.net/wiringPi # Or sudo apt install wiringpi

2. Web Server Configuration:

   • Remove the default Apache index page:

     sudo rm index.html

   • Create a new PHP file for the web interface:

     sudo nano index.php

     Add HTML and PHP code to control GPIO pins. (See original instructions for detailed code).

3. Verifying WiringPi Installation:

   • Check WiringPi:

     gpio -v gpio readall

   • Test GPIO control:

     gpio -g write 17 1

4. Setting Permissions:

   • Add PHP user to GPIO group:

     sudo usermod -a -G gpio www-data

   • Modify sudo permissions:

     sudo visudo

     Add www-data ALL=NOPASSWD: ALL in the file.

5. Notifying via Lobby Station:

   • Automate office visit notifications using a Raspberry Pi in the lobby. When a button is pressed, it signals the office Raspberry Pi, activating a buzzer.

   • Enable remote GPIO in raspi-config.

   • Implement a Python script using RPi.GPIO and gpiozero libraries. (Refer to the original guide for the script).

Final Steps

• Ensure all components are correctly installed and configured.

• Test the system in a controlled environment before implementing in a patient care setting.

Note: This guide is intended for those familiar with basic Raspberry Pi setup and programming. The paging system can be a valuable tool in a healthcare setting, improving communication between patients and staff.

Guide: Setting Up Raspberry Pi Pico Ws for MQTT-Based Communication

This guide will help you set up two Raspberry Pi Pico Ws to communicate with each other over a Wi-Fi network using the MQTT protocol. Additionally, it includes steps for communication between a Raspberry Pi Pico W and a Raspberry Pi 4B.

Part 1: Setting Up Pico Ws for MQTT Communication

Requirements:

• Two Raspberry Pi Pico W boards

• USB mic and audio jack for Pi Pico W

• Access to a Wi-Fi network

• An MQTT broker (e.g., Mosquitto running on a Raspberry Pi 4B or another device)

Setup for Each Pico W:

1. Configure GPIO Pins:

   • On Pico 1, configure a push button on GPIO 0.

   • On Pico 2, set up an LED and buzzer on the desired GPIO pins.

2. Install Required Libraries:

   • Use MicroPython to install libraries for network, urequests, and umqtt.simple.

3. Configure Wi-Fi and MQTT:

   • Set the Wi-Fi SSID and password to connect both Picos to the same network.

   • Set up MQTT broker details (IP, port, username, password) in the script.

   • Assign a unique MQTT topic for communication, e.g., pico/led.

4. Pico W Code:

   • For Pico 1, write a script to send an MQTT message when the button is pressed.

   • For Pico 2, write a script to listen for MQTT messages and activate the LED and buzzer accordingly.

Part 2: Setting Up Raspberry Pi 4B as MQTT Broker

1. Install Mosquitto MQTT Broker:

   sudo apt install mosquitto

   sudo apt install mosquitto-client

   sudo systemctl start mosquitto

   sudo systemctl enable mosquitto

2. Configure MQTT Broker:

   • Set up the Pi 4B with a static IP for consistent access.

   • Optionally, create MQTT user credentials for secure communication.

3. Pi 4B Script:

   • Write a Python script using paho.mqtt.client to control an LED based on MQTT messages.

4. Testing MQTT Communication:

   • Use the mosquitto_sub command to subscribe to the MQTT topic and test communication:

     mosquitto_sub -h <your_pi4_ip> -u <your_mqtt_user> -P <your_mqtt_password> -t pico/led

Part 3: Final Integration and Testing

1. Deploy Scripts on Pico Ws and Pi 4B:

   • Transfer and run the respective scripts on each device.

2. Test the System:

   • Press the button on Pico 1 and observe if Pico 2 responds with LED and buzzer activation.

   • Monitor the MQTT messages on the Pi 4B for debugging and verification.

3. Troubleshooting:

   • Ensure all devices are on the same Wi-Fi network.

   • Check MQTT broker settings and network configurations.

   • Verify the GPIO connections on the Picos.

Notes:

• This setup allows for scalable IoT applications using Raspberry Pi Picos and MQTT.

• Ensure network security, especially when communicating over MQTT.

• The MQTT protocol enables efficient and reliable communication between IoT devices.