arshnooramin/ioto-scope

Internet of Things Oscilloscope

Internet of Things Oscilloscope

ESP32-based IoT Oscilloscope

Purpose

An oscilloscope is an essential tool for professionals in a variety of fields, especially for Electrical and Computer Engineers. Handheld oscilloscopes like the Analog Discovery have revolutionized the workflow of ECEs through USB oscilloscopes that provide an easy-to-use interface.

This project takes the approach of Analog Discovery to the next level by introducing a handheld oscilloscope that’s also internet connected. This form factor creates possibilities for workflows that are were not possible with conventional oscilloscopes - remote labs, smart home/lab control, automatic data collection are some of such possibilities. The Internet of Things Oscilloscope or ioto being introduced in this project is based around the ESP32 SoC.

Features and Advantages

Web Application

The most important feature of ioto is its custom web application which can be accessed via an access point IP address served by the ESP32. Since the web application is the control mechanism for ioto, it makes the device truly wireless. This means a user can create an experimental setup with ioto and can remotely control equipment, record and export data, and monitor the experiment without having to be physically present in lab. The interface of the web application is incredibly intuitive and is divided into two sections: Digital and Analog, corresponding to ioto's two main functionalities.

Digital IO

ioto contains 6 digital channels (which can be easily expanded). The digital channels can set as input or output and can read or set logic HIGH (1) or LOW (0) on each of the channels independently. The state and value of each of the digital channels can be set using the web application. The digital IO functionality can support a multitude of applications from basic button/interrupt handling and LED control to complex combinational logics and circuits.

Analog Scoping

ioto contains 2 analog channels (which can also be easily expanded). The analog scope can read analog voltages in the range of 0-2.5V. Each channel independently reads the voltage and plots it on a graph on the web application. The plot layout and sampling frequency can be modified and graphs can be exported as images. The analog scoping functionality can be used in a multitude applications as well from sensor data recording to circuit debugging.

Technical Specifications

• Analog channels - 2 (expandable to 18 for ESP32-S2 dev board)
• Analog-to-digital conversion (ADC) resolution - 12 bits
• Measurable analog input voltage range - 0 mV ~ 2500 mV (at 11 dB attenutation)
• Digital channels - 6 (expandable to 34 for ESP32-S2 dev board)

How to Use

Hardware Required

• ESP32-S2 development board (or any other development board with the ESP32 SoC)

Connections

ESP32-S2	ioto
GPIO42	D1
GPIO41	D2
..	..
GPIO37	D6
GPIO7 (ADC1_6)	Channel 1
GPIO6 (ADC1_5)	Channel 2

NOTE: The above connections can be modified

Running the Code

Clone this repository

git clone [email protected]:arshnooramin/ioto.git
cd ioto

Add Wi-Fi credentials to config file (menuconfig > "Application Configuration")

idf.py menuconfig

Compile and flash to the ESP32 development board

idf.py build
idf.py -p [PORT] flash monitor

Example Output

If everything worked as expected you should get the following output

I (2440) esp_netif_handlers: sta ip: [Web App IP], mask: [..], gw: [..]
I (2440) main: got ip:134.82.156.239
I (2440) main: connected to ap SSID:[WiFi Name] password:[WiFi Password]

You can now navigate to the IP Address being display to access the ioto Web Application.

How It Works

At the center of the ioto project are WebSockets. WebSockets are used here to allow for a two-way communication between the browser and the ESP32.

The ioto project has two main components: the web application and the ESP-IDF program. The web application is built using HTML/CSS and JavaScript. HTML/CSS defines the structure of the website and how it looks. JavaScript includes WebSocket code so that the user interactions recorded on the web application via DOM events can be sent back to the ESP32. The ESP32 then performs the function that the user requsted and sends information back to the web application/browser where it is displayed to the user.

It is important to note that the HTML, CSS, and JavaScript files are actually served by the ESP32 itself, the ESP32 here acts as an access point. Whenever a stream of data is to be requested from the ESP32, a separate websocket is opened to which the ESP32 streams data and JavaScripts listens for this data and plots it using Plot.ly.