Welcome to eSim and Arduino on Cloud’s documentation!¶

The project aims to provide a facility for a user to design different types of electronic circuits and arduino projects and simulate them by providing simulation parameters on the web. The detailed features will be updated soon.

Overview¶

eSim on Cloud¶

This system allows the users to draw analog and digital circuits and simulate them. The users have a facility to drag and drop components from the left pane onto the schematic grid on the right pane. The components on the grid are connected using wires. The circuit can then be simulated using the different simulation parameters (DC Solver, DC Sweep, Transient analysis, and AC analysis). The basic ERC check enables the users to find out errors if any. The size of the schematic grid can be changed from A1 to A5 paper sizes along with portrait and landscape modes. The users can also print the circuit or save it in pdf format for documentation purposes.

Arduino on Cloud¶

This system allows the users to drag and drop Arduino components from the left pane onto the working space on the right. The pins of the Arduino board can be connected to various input/output devices like LED, motor, push button, etc using wires. There is also a facility to change the color of wires, LEDs, and such components, so as to differentiate the easily. The users can then proceed to write their code in the code window which is then simulated. There is an option for the users to print or save it in pdf format for documentation purposes. The basic ERC check enables the users to find out errors if any.

Note

This docs is created using Read the docs and we will be glad to receive pull requests for updating the same. Please go through the Contribute section to know more.

Architecture and Installation¶

The production environment consist of the following docker containers:

Container Name	Description
nginx	Used as a reverse proxy to route requests to appropriate endpoints and loadbalancing
celery	Used as a reverse proxy to route requests to appropriate endpoints and loadbalancing
redis	Used as a cache and a task queue for Celery
mongodb	Container running MongoDB Database
db	Container running MYSQL Database
django	Container running the main Django Backend serving all APIs
arduino-frontend	Container running node 10 helping build Angular app for Arduino Simulation Webapp
eda-frontend	Container running node 10 helping build React app for EDA CircuitSimulation Webapp

Note

These containers depend on .env.prod file, configuration details can be reffered from Environment Variables.

Installation and Usage¶

It is essential that docker and docker-compose are installed on a system before following the steps.

Production Environment¶

git clone git@github.com:frg-fossee/eSim-Cloud.git && cd eSim-Cloud
cp .env .env.prod
docker-compose -f docker-compose.prod.yml –env-file .env.prod up –scale django=1 –scale celery=3 -d

Note

Please change the default passwords in the .env.prod file to secure your instance against attackers.

Development Environment¶

git clone git@github.com:frg-fossee/eSim-Cloud.git && cd eSim-Cloud
git checkout develop
Configure docker with github packages for pulling pre built images
echo $GITHUB_TOKEN | docker login docker.pkg.github.com –username [github_username] –password-stdin
/bin/bash first_run.dev.sh

For running only the backend containers¶

docker-compose -f docker-compose.dev.yml up django

For running only the eda-frontend container with backend¶

docker-compose -f docker-compose.dev.yml up eda-frontend

For running only the arduino-frontend container with backend¶

docker-compose -f docker-compose.dev.yml up arduino-frontend

Useful Commands¶

docker exec -it <container ID> <command>
eg. docker exec -it b7e7acf2283e /bin/sh
sh migrations.sh inside a docker container to apply db migrations manually
To seed libraries - python manage.py seed_libs –location kicad-symbols/ inside container
To remove seeded libraries - python manage.py seed_libs –clear inside container

Environment Variables¶

Variable	Description	Default
PYTHONUNBUFFERED	allows for log messages to be immediately dumped witout buffering	True
SQL_ENGINE	SQL Engine used by Django	django.db.backends.mysql
SQL_HOST	Hostname for database server	db
SQL_PORT	Port for database server	3306
DJANGO_DEBUG	Debug mode setting for Django	True
MYSQL_ROOT_PASSWORD	Root password for MYSQL	password
MYSQL_DATABASE	Default database name for MYSQL	esimcloud_db
MYSQL_USER	Username for MYSQL Server	user
MYSQL_PASSWORD	password for MYSQL Server	password
MONGO_INITDB_ROOT_USERNAME	Username for MongoDB Initial Database	user
MONGO_INITDB_ROOT_PASSWORD	Password for MongoDB Initial Database	password
MONGO_INITDB_DATABASE	MongoDB Initial Database name	esimcloud_db
TAG_MYSQL	MYSQL Docker Image Tag to pull ( Version )	8.0
TAG_REDIS	Redis Docker Image Tag to pull ( Version )	alpine3.11
TAG_MONGO	Mongodb Docker Image Tag to pull ( Version )	4.2.6
GUNICORN_WORKERS	Number of Gunicorn workers to spawn per container	5
CELERY_WORKERS	Number of Celery workers to spawn per container	5
EDA_PUBLIC_URL	public url used to build react frontend files	http://localhost/eda
ARDUINO_BASE_HREF	public path used to build angular frontend files	/arduino/

Note

Please change the default passwords in the .env.prod file to secure your instance against attackers.

Introduction to eSim on Cloud¶

eSim Development Flow¶

_images/flow_schematic_to_simulation.png

Reading Component Symbol Library files and Rendering in the Browser¶

The Kicad symbol libraries ‘.lib’ and ‘.dcm’ (https://github.com/KiCad/kicad-symbols) are parsed to generate SVG files that are compatible with the mxgraph (javascript graph library). These components are generated only once and are cached. These generated SVG files are read and rendered in the component list (left pane) using mxgraph.

Generating XML files¶

The components from the left pane are dropped onto the schematic grid. By default, the size of the grid is A4, which can be changed from A5 to A1. The components connected by wires are converted to XML format using mxgraph, whenever the circuit is saved by the user. This XML is used to save and re-open the saved circuits. This XML is also used to auto annotate the circuit, and in performing ERC checks as well.

Generating Netlist¶

Using the mxgraph object, a netlist is generated (compatible with ngspice simulator) when the user clicks on the ‘Simulation’ or ‘generate netlist’ button. The simulation parameters are supplied by the user based on the simulation type chosen by the user. The following are the different parts of netlist generation:

Title: title of the schematic diagram
RC Circuit
Model: All spice models given by users will be listed here. These are extra parameters which are not delivered with ngspice. They are device manufacturer specific and may be obtained from their web sites or from other sites
.model BC546B npn ( IS=7.59E-15 VAF=73.4 .........)
Netlist: Text description of circuit. It has all components listed with connecting nodes, parameters and spice model (if specified by the user). This is generated with the help of mxgraph object. An example is shown below
r1 in out 1k c1 out gnd 10u v1 in gnd pwl(0m 0 0.5m 5 50m 5 50.5m 0 100m 0) Q1 intc intb 0 BC546B
Control Line: It has all simulation parameters. It is generated depending on the type of simulation and the parameters specified by user
.tran 10e-03 100e-03 0e-03 // Transient analysis .ac dec 10 10 1Meg // AC Analysis
Control Block: All Interactive commands to actually produce output for given schematic.
.control run print all > data.txt .endc .end

Simulation¶

When the ‘Simulate’ button is clicked, the ERC checks are performed. If all goes well then the netlist is generated. If not, the error(s) are shown to the user.
This netlist is sent to the backend services. Using the distributed queueing mechanism of Celery, asynchronous requests (netlist files) are kept in queue and passed onto Ngspice.
Ngspice then outputs a text file with all the coordinates required to plot the graph.
This textfile is then parsed using an inhouse parser to convert the data of the text file into an organised data structures (JSON). The simulation graph is then plotted and rendered based on the data returned by this JSON using chartjs.

JSON format returned by parser¶

As mentioned above, the output produced by ngspice is converted to JSON. The format is given below:

{
    total_number_of_tables: <int>,
    isGraph: <bool>,
    data:[
        {
            labels : [ ], x : [ ], y : [ [ ] , [ ] ] ,
        }
    ]
}

total-number-of-tables: The number of tables present.
isGraph: True, if the data is a graph, False if the data is just a table.
data: An array which contains one or more objects depending on the input provided to the parser.
labels: An array which contains all the labels that have to be present on the graph. Eg. [“time”, “vin”, “vout”].
x: An array containing all the x co-ordinates for a set of graph. E.g. Time on x-axis. This is a linear array as the x coordinates will be the same for different set of y coordinates.
y: A 2D array containing y co-ordinates for different graphs.

Features¶

The schematic editor is divided into 3 panes. The left pane consists of the Component List and a facility to search components. The middle pane consists of the grid on which the components will be dropped and the circuit will be designed. The right pane consists of the grid properties, description of the circuit, and components position. More details are given below.

Component categories¶

The kicad components are categorized as follows, where each component has Name, Description, Keywords, and Datasheet.

Analog
Device
Triac_Thyristor
Transistor_IGBT
Diode
Transistor_FET
pspice
Oscillator
eSim_Sources
eSim_Hybrid
Motor
LED
Transistor_BJT
power
4xxx

Searching Component¶

Rather than going through categories and locating the component symbol, one can also search a component by typing in the textbox given, using the filters like Name, Keyword, Description, Component Library, and Prefix.

Grid size and Orientation¶

The size of the grid can be changed from A1 to A5 and offers Portrait and Landscape mode

Components Position¶

Using the this box, one can access and view the circuit which do not fit onto the specified grid size. Its like accessing another page. This situation arises when one has a large circuit and changes the grid from a larger size to a smaller one.

Schematic Description¶

A text area in which one can write the description about the circuit.

Basic Editor Operations¶

The following basic editor functions are supported:

Undo
Redo
Delete
Zoom in
Zoom out
Default size
Rotate
Print
Clear All: Clear the schematic drawn

Gallery¶

Sample circuits are available in the gallery for anyone to refer and use. These circuits can be opened, saved, and simulated.

Saving and Re-Opening¶

The circuits are saved only of an authenticated user and are viewed on the user dashboard. The same can be reopened as well for further editing.

Dashboard¶

A place where the authenticated user can view the different circuits designed by him/her. Then user can open the saved circuit into the editor by clicking on Launch in Editor.

Export¶

Image: The circuit can be exported as jpeg, png, and svg. This is useful for documenting and printing.
JSON: The circuit can be exported as JSON so as to open it again using the Upload feature.

Open Schematic¶

The schematic can be opened using the following methods:

Uploading file: One needs to upload the file in JSON format i.e. which was exported using this tool.
Local: The circuits saved by the authenticated user.
Gallery: The sample circuits available in the gallery for anyone to refer.

ERC Check¶

Basic ERC check is done for simulating a circuit. For example, if the wires are connected or not.

Generate Netlist¶

Based on the circuit a netlist is generated. The internal process of generating a netlist was described in the previous section.

Simulate¶

There are four simulation modes as follows

DC Solver: A DC simulation attempts to find a stable DC solution of your circuit.
DC Sweep: A DC Sweep will plot the DC solution of your circuit across different values of a parameter of a circuit element. You can sweep any numerical parameter of any circuit element in your circuit.
Transient Analysis: A Transient analysis does a Time-Domain Simulation of your circuit over a certain period of time.
AC Analysis: AC Analysis does a small signal analysis of your circuit. The input can be any voltage source or current source.

Spice simulator¶

Using the spice simulator one can type the netlist in the code editor box and simulate it. Simulation result window will popup displaying the result.

Note: Add > data.txt at the end of the control line.

.control
run
print all > data.txt
.endc
.end

eSim Gallery Examples¶

eSim gallery has 6 example circuits. You can open, re-design, save, and simulate them. These are listed below.

Voltage Divider¶

Simulation Type: DC Solver
Simulation Parameters: None
Simulation

RC Circuit¶

Simulation Type: Transient Analysis
Simulation Parameters
- Start Time: 0
- Stop Time: 100m
- Step Time: 10m
Simulation

Dual RC Ladder¶

Simulation Type: Transient Analysis
Simulation Parameters
- Start Time: 0
- Stop Time: 50m
- Step Time: 50u
Simulation

Bipolar Amplifier¶

Simulation Type: Transient Analysis
Simulation Parameters
- Start Time: 0
- Stop Time: 10m
- Step Time: 10u
Simulation
Simulation Type: AC Analysis
Simulation Parameters
- Type: Decade
- Points: 10
- Start frequency: 10
- Stop frequency: 10Meg
Simulation

Shunt Clipper¶

Simulation Type: DC Sweep
Simulation Parameters
- Component: V1
- Start Voltage: 0
- Stop Voltage: 1
- Step Voltage: 1m
Add Expression: -v1#branch
Simulation

RC Circuit Parallel¶

Simulation Type: Transient Analysis
Simulation Parameters
- Start Time: 0
- Stop Time: 30m
- Step Time: 10u
Simulation

Screenshots¶

Introduction to Arduino on Cloud¶