EasyEDA: Free online EDA Product how-to

Transcription

1 EasyEDA: Free online EDA Product how-to Andy Fierman - May 07, 2014 Introduction Using a simple, three transistor clamp circuit as an example, this article introduces the features of EasyEDA and gives an overview of how to use it to create a schematic, run a simple simulation on it then lay out and order the PCB. All without leaving the tool. For a more in depth look at the many features and functions of this very versatile EDA tool, we recommended that you have a look at the EasyEDA Tutorial and some of the many example circuits on the site. What is EasyEDA? EasyEDA is a new, free, web based EDA tool. There s no need to install any software. Just open EasyEDA in any HTML5 capable, standards compliant web browser. [1] EasyEDA provides: Schematic capture Schematic Design Manager ngpice-based simulation Simulation WaveForm viewer PCB layout PCB Design Manager PCB Design Rule Checking Export PCB netlist in Protel

2 Kicad PADS formats Spice netlist Simulation data Schematics, symbols, PCBs and footprint in JSON format All drawings as images in pdf image SVG formats Creation of Bill of Materials (BoM) reports Import Altium/ProtelDXP Ascii Schematic/PCB Eagle Schematic/PCB/libs LTspice Schematic/symbols (may require editing for ngspice compatibility) Kicad libs/modules (footprint libraries) Spice models and subcircuits Symbol creation and editing Hierarchical schematics (passive drawings and active simulation schematics) Spice subcircuit creation PCB footprint creation and editing Schematic symbol, spice model and PCB footprint library management Online sharing of - and collaborative working on - schematics, simulations, PCB layouts, designs and projects Very low cost PCB for projects developed in the tool (but with no user lock-in to EasyEDA: Gerbers can be downloaded and sent to any PCB supplier)

3 A first look at the EasyEDA Editor page The first time visitor to the EasyEDA Editor page is taken through a one-time short guided tour of the essential features of the tool. It is well worth spending a minute or two going through this and observing some of the drop-down menus that can still be activated under the buttons highlighted during the tour to get the hang of some of the many functions that are common across all the Schematic, Symbol Lib, Spice Symbol, Spice Subckt, Simulation, PCB Layout and PCB Lib Creation canvasses of the tool. Almost all the features of EasyEDA can be used, even without signing up for an account, by saving files in Anonymous mode. Files can then be reopened and edited simply by pasting their urls back into the browser. To use the more powerful file management and sharing features however the user needs to register for an EasyEDA account from the simple Create an account dialogue accessed from the Log in button: Figure 1. Creating an account. Sign up is very simple and can also be done using an existing Google or Yahoo account. To save a lot of head scratching, it it is well worth clicking on the Reading this before you register link and having a look through the Tutorial because once started with the tool itself, it can get quite addictive! This tutorial can always be accessed from the i button at the top of the main window and from the Help buttons in various dialogues.

4 Getting started After logging in, the next step is to Create a new Project. A Project is a folder in which schematic, simulation and PCB files can be created and stored: Figure 2. Creating a new Project. Projects can be private or public and via the Modify option can be switched between the two states. Additional features are available, such as entering more detailed information with Markdown syntax or allowing other registered users to comment on projects.

5 Figure 3. Modifying the status of a Project. Only the registered user can modify files in private or public projects but they can be shared with read only or read/write access with other registered users: Figure 4. Setting Access Control privileges for a Project.

6 Now the fun can start with the creation of a New Schematic, saving it (from the Document menu or simply Ctrl+S) with a title in the new project but with the option of choosing others and adding a description of the schematic: Figure 5. Creating and saving a New Schematic. Clicking in the drop down options box in the left hand navigation panel under the EasyEDA logo shows a list of available Schematic symbols and PCB Package libraries, including libraries from some of the well known Hobbyist, Maker and Hacker sites plus a selection of Kicad PCB Packages. Figure 6. The left hand navigation panel. Since the circuit is to be simulated, the EasyEDA Libs are chosen because these are all ready-to-use parts with simulation models and default packages associated with them. Simply clicking on a part and then clicking on the Schematic canvas places a component. Some parts have a down arrow, which when clicked, shows variants of parts that can also be placed.

7 Figure 7. Selecting components. Exit component placement by right clicking. Components can then be wired up simply by clicking on the end of device pins, dragging the green wire and clicking to add corners until clicking on the destination ends the wire. The wiring mode can also be invoked using the W key or from the floating Wiring Tools toolbar. Again, double right clicking exits the wiring mode. Wires can be edited by selecting them and dragging the green handles around. Red dots clearly indicate that wires are joined and not just crossing.

8 Figure 8. Placing components. Extensive use is made of Hotkeys in EasyEDA. A full list of these useful shortcuts can be found and edited under the blue gear Config icon at the top of the window. The Spacebar or the R key rotates and the X and Y keys flip parts whilst the device model name can be edited directly by double clicking on it or by editing it in the right hand Properties panel. Clicking back on the canvas enters the change. Figure 9. Editing components in a schematic. The package type of the device can be edited via the right hand Properties panel: clicking on the package attribute opens a selection dialogue where - with the help of a preview of the PCB footprint in the floating Preview toolbar - the required package can be searched for:

9 Figure 10. Selecting the device package type. Components and wires can be dragged using the mouse or by selecting them and using the arrow keys. The effects of these are slightly different in terms of whether wires are dragged with them or not. A left-to-right drag selects everything fully enclosed by the box whilst a right-to-left drag selects everything the box intersects. Whilst it is possible to draw a simple schematic like this on a single sheet, to simplify the creation of a test jig to simulate the schematic later on and to demonstrate the multi-sheet capability of EasyEDA, a second schematic sheet can be created with just the signal and power connectors from the Sparkfun Libs. The nets in both schematic sheets are simply connected by netlabels (added using the N hotkey or from the floating Wiring Toolbar) and the global ground net. After adding, some text (using the T key), adjusting text attributes such as size, font and colour (from the right hand Properties panel), the completed schematic sheets, ready to be pushed through to PCB layout with a click of the Convert Project To PCB button on the top toolbar, look like this: [2]

10 Figure 11. The completed connector and clamp schematic sheets viewed in two browser windows. Note that the two schematics can be viewed simultaneously simply by opening a duplicate browser window and selecting the appropriate tab in each EasyEDA window. This works for any number of tabs so for example, the schematics and a PCB layout can be viewed in the same way. Before looking at how to push the schematics through to PCB layout, the next section briefly describes some of the simulation capabilities of EasyEDA. [3] Simulation Simulating the schematic Simply by cloning the clamp circuit and the connectors schematics into separate simulation Project and then renaming and editing only the connectors schematic to replace the connectors with input signal and power supply sources for input and power and adding input and output voltage probes, a copy of the schematic can be made ready for simulation: [4]

11 Figure 12. A copy of the schematic ready for simulation. Clicking on the Green Man icon and selecting Run the Project opens the simulation dialogue box and from there the type of simulation and the relevant simulation parameters can be set and then run by clicking on the Run key. Depending on the type of simulation that is run, the results and any error messages are shown in text form in the Simulation Results > Show your simulation report window or in plot form in the powerful WaveForm viewer. A spice netlist of the simulation can be downloaded from the Show your simulation report window and plots in the WaveForm viewer can be analysed using the onscreen cursors and downloaded in CSV format for post-simulation processing in 3rd party tools such a LibreOffice Calc, Gnumeric or SciLab. The display area, trace, grid and background colours and the placing and hiding of traces on up to 3 grids in WaveForm can all be easily tailored from the WaveForm Config button. WaveForm plots can also be saved into Project folders where they can be re-opened and manipulated the same as when they are first generated. Saved WaveForm plots can be exported in a.pdf,.png and.svg formats. So, for example: Green Man > Run the Project > Transient > Run

12 generates a time domain WaveForm plot: Figure 13. A time domain WaveForm plot with cursor showing V(clamp) values. Left-click-and-drag in the WaveForm window shows dy and dx values. Returning the cursor to near the starting point of the drag returns the cursor to x and y values whilst releasing the left-click zooms the area in the rectangle. Double-left-click resets the zoom and returns the cursor to x and y values.

13 Pushing the schematic through to PCB design. Going back to the Project containing passive or non-simulation schematic and clicking on the Convert Project To PCB button opens the Verify the packages dialogue. Any changes and corrections can be made via the Update the symbol s package dialogue by double-clicking on the relevant part: Figure 15. Checking and correcting packages prior to PCB layout. Clicking Build PCB then opens the PCB design canvas with a board outline - calculated from the device packages and the track and gap information set in via Super Menu > Miscellaneous > Design Rule Check - and all the components set to one side, connected by ratlines ready to lay out.

14 Figure 16. Initial PCB layout with auto-calculated board outline. Component placement and manipulation, track laying, and text editing functions are very similar to the equivalent functions in the Schematic Editor canvas with the exception that the T hotkey is used to change to the Top layer (the B and 1 to 4 keys are used for the bottom and up to four inner layers respectively). After layout is complete, doing Super Menu > Miscellaneous > Design Rule Check > Check will show up any errors:

15 Figure 17. Results of running a Design Rule Check. Correcting the track clearance error then gives a clean bill of health: Figure 18. Track to track error corrected: good to go! Time to run and eyeball the Gerbers using a downloaded copy of the Free and Open Source Software gerbv:

16 Figure 19. Generate and check Gerbers. Finally, PCBs can be ordered directly from EasyEDA or the Gerbers can be sent to any other manufacturer: Figure 20. Order the PCBs

17 Conclusion It is difficult to do justice to such a flexible and comprehensive tool in just a few pages and screenshots. There are many powerful functions such as symbol and footprint creation and editing, basic hierarchy, adding models and subcircuits to spice symbols and schematics, the Schematic Design Manager, BoM Report creation and tricks with JSON file editing, that have been left out. Similarly, much has been skipped over about the PCB layout side of EasyEDA including track editing, changing track widths on the fly, Copper Areas, the PCB Design Manager and PCB Design Rule Checking. Much more in-depth information can be found in the EasyEDA Tutorial but it is hoped that this article has at least given the reader a quick start guide on how to drive EasyEDA and a flavour of the many features it provides to make an Easier EDA Experience. Also see: Upverter Web EDA gets major revamp In-browser circuit simulator tackles circuits from simple to complex Behind the curtain: Rendering 16,000+ schematics in the cloud Extended-precision simulation cures SPICE convergence problems Slideshow: Free online design, simulation, parts search tools Recent versions of Chrome, Chromium, Firefox, Safari should be OK. Users of Internet Explorer may have to upgrade to IE9+ [1] If desired, linked images can be added by entering their urls into the Image button on the Drawing Tools floating toolbar. [2] For brevity, this is a very basic overview of simulation in EasyEDA. Examples of more advanced simulation features, including the use of the ngspice control block to script advanced simulations of flat schematics can be found in the Spice-simulation-skills public Project. [3] This is necessary to avoid errors due to duplicate part references when trying to run simulations, generate Spice Netlists and BoM Reports and when pushing through to PCB. [4]