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Creating a PCB symbol from a datasheet
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NuttyProfessor47 6 years ago
I need to create a PCB symbol for a board mounted mains transformer. I've read the tutorial and referenced a couple of other sources, but the instructions for drawing the physical outline seem to fail at the first step. There is no line drawing tool. I can place the pads, but how does one draw the outline with only the PCB tool box available? The drawing toolbox doesn't appear when a PCB Lib pane is opened. I've tried selecting different layers (top silk, board outline) but drawing a shape with the cursor only draws a dotted box for as long as left mouse is held down, and using the "track" tool for the outline doesn't work either. I'm sure as before that I'm missing something obvious to others, but it's not to me.
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andyfierman 6 years ago
You mean a PCB package, footprint or Lib rather than a symbol (which usually refers to a Schematic Symbol). In the floating `Layers` pallette in the PCB Lib Editor, click on the yellow square at the left hand end of the `Top Silkscreen` layer. The editing pencil moves to show you are editing that layer: Then Select the `Track` tool and draw the outline. ![enter image description here][1] * Although EasyEDA will trap and correct outlines drawn over or right up to pads, it is bad practice to draw outlines like that. If you want to indicate a continuation of an outline in the PCB Editor that will extend through a pad or for a package outline that extends beyond the physical edge of the PCB then you can draw those parts of the outline on the `Document` layer, again using the `Track` tool. Here's an example of using the `Document` layer to continue an outline through pads: MICRO-USB5+6P-SMD-0.65-B Zoom in to see the detail. :) [1]: /editor/20170921/59c2d38e7f097.png
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NuttyProfessor47 6 years ago
@andyfierman OK. To clarify what I'm trying to do. I've found a transformer schematic symbol in the EELib that meets my needs; primary and two secondaries. The type I'm using, a Block VB series, 3.2VA version is not in any of the part libraries that I have found so I need to create the PCB footprint. Circles to mark where the pins go is done. Not trivial, because pads don't work at a silk screen layer, and circles don't centre over the centre if you get my drift. But manualy adjusting X,Y co-ordinates got that fixed eventually. Then came the question of the outline. Thanks for your help with that, but I'm afraid this total newcomer to EasyEDA still hasn't mastered some of the fundamentals of the GUI. ![Progress so far, with dimension checks in place. Thay'll be removed when it's complete.][1] I've now tumbled that one has to release the mouse button to draw the line (every drawing package I've used before it's held down until the line is finished or the required shape is complete, square, rectangle circle.) So far so good. But when I close the rectangular outline, how do stop drawing lines everwhere the cursor goes? Escape does it but then the whole line disappears. The video tutorials are very helpful, but can't show what the operator is doing with the mouse buttons, only where he (she) is pointing. The issue I'm having now, and moving the canvas are both cases in point. I've seen the canvas be moved, but how? I've seen lines being drawn, but how? [1]: /editor/20170921/59c379c76fadc.PNG
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Tutorials 6 years ago
Hi I wish that can help. https://easyeda.com/Doc/Tutorial/PCB.htm#Track https://easyeda.com/Doc/Tutorial/PCB.htm#Pad https://easyeda.com/Doc/Tutorial/PCB.htm#Layers-Tool https://easyeda.com/Doc/Tutorial/PCBLib.htm#PCBLib-Tools https://easyeda.com/Doc/Tutorial/PCBLib.htm#Others https://easyeda.com/Doc/Tutorial/PCBLib.htm#Edit-PCBLibs
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andyfierman 6 years ago
@NuttyProfessor47, Please have a look through the **Basic Driving Skills** section of the Tutrial: https://easyeda.com/Doc/Tutorial/Introduction.htm#Basic-Driving-Skills and in particular: https://easyeda.com/Doc/Tutorial/Introduction.htm#Left-clicking https://easyeda.com/Doc/Tutorial/Introduction.htm#Right-clicking https://easyeda.com/Doc/Tutorial/Introduction.htm#ESC-key :)
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NuttyProfessor47 6 years ago
@andyfierman Thanks. I never came across those. I'll get there in the end! :)
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andyfierman 6 years ago
This is a good place to start.... https://easyeda.com/andyfierman/Welcome_to_EasyEDA-31e1288f882e49e582699b8eb7fe9b1f :)
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NuttyProfessor47 6 years ago
@andyfierman Thanks again. Shame the offline version is now defunct. I was relying upon it to work whilst on the road. Anyway, I've achieved adding some transformer footprints and linking them to schematics, but it seems a little odd to me to associate a part number with the schematic and not the footprint which is what changes when a different size is chosen whilst the schematic symbol stays the same. Finally, how does one add the photo that some library entries seem to have?
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andyfierman 6 years ago
* You need to think of the symbol together with a package (PCB footprint) as representing a physical part that you can buy from somewhere. If you change the value or the package of a device then you need to buy a different physical part. So, you create a schematic symbol for a device and then assign it a package. If you change the device from say a 110V to 12V to a 110V to 15V transformer then you should create a new schematic symbol for it - even if it has the same package - because it is a different part as far as ordering it up from the BoM. It will have a different manufacturer's part number and a different supplier's part number. It may also have a different manufacturer and/or supplier. If it has a different package too then that is unarguably a different part so it should have a different schematic symbol. If you wish, you can simply copy and then edit the supplier, manufacturer and package information of a symbol that you have already used in a schematic. That's fine too but if it's a part such as a transistor or a regulator that you use in many different designs then it probably makes more sense to create a dedicated symbols for it. Then you don't have to keep going back to previous schematics to find an instance of it to copy and paste (though you can create a private schematic sheet with them all on it so you can just open that and grab one). * The photo is added on the server by EasyEDA. It is not accessible by our users. If the ability to upload a photo is important to you then please consider raising a Feature Request to get it onto the ToDo list (though I suspect this feature would have to be subject to moderation by EasyEDA!).
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NuttyProfessor47 6 years ago
@andyfierman Thanks again for your most comprehensive answer. Dealing with the last first, photos are not important; I just noted that some components have them. For the PCB mounted transformers I'm creating footprints for I though it might help other users to see what they look like. I already know! I take your point about the symbol and footprint pair representing a specific component. It's just that in design software I've used before, the symbol for a twin secondary transformer for example, never changes, regardless of its voltage, current, and power ratings. It's only the footprint that must represent the physical characteristics of the chosen part. The same is true of transistors, diodes, and most passive components. Hence is see the creation of a multitude of identical schematic symbols as inefficient. I've been used to a system where a library entry consists of three elements, not two. The schematic symbol for, say, a diode, it's associated package, maybe TO92 footprint with a defined pad spacing, and the device information, say 1N4001. The schematic diagram used the symbol AND device information and showed the devices type specific information. Hence ALL conventional diodes shared one schematic symbol, used one of the available range of package and pad spacing footprints, and only the text description (device) entry was unique. In the end just a different way of doing things. I'm learning. It's just like a foreign language in many ways. Not wrong just different. I'll go through the tutorials again to get a better handle on creating the combinations of schematic and footprint parts. Mine seem to persist as separate, dissociated symbol library and part library entries and I need to discover the linking process. I think I'd better stop pestering you now. You've done more than your fair share to help me get started. Thank you again.
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andyfierman 6 years ago
* The key thing to understand is that if you find/edit or create a schematic symbol and you find/edit or create a package (PCB footprint or PCB Lib) then they will appear in the library. If, when you create a symbol, you assign a package that exists in the library to it then when you search for that symbol, it will show the schematic symbol **and** the associated package. This does not happen if you just edit symbols or package assignments within a schematic because you are not changing anything in the library. And as described in: https://easyeda.com/andyfierman/Essential_checks_before_clicking_the_Convert_Project_to_PCB_Update_PCB_or_Import_Changes_buttons_-7d2c6484b0c74aea930b1acf6459cd39 it is just a bad idea to edit packages within a PCB. * You can also of course simply place a generic symbol for a device and then edit the supplier, manufacturer and package information to tailor the symbol for the specific part that you need for your a schematic. That's also absolutely fine but again, if it's a part that you use in many different designs then it probably makes more sense to create a dedicated symbol for it. This is what gEDA refers to as the 'Light' vs. 'Heavy' symbols argument. Do you have a small library of generic symbols and leave it to the user to tailor each part only within a schematic to meet their requirements (Light) or do you have a big library with each part having all the dsetails of the specific manufacturer, manufacturer part number, supplier, supplier part number, part description, footprint and so on. 'Light' is good if you know exactly what you are doing and what you want but leaves a lot open to error for newbies not used to describing and specifying components. 'Heavy' is good if you just want to browse and say 'I'll have that one' and slap it down into a schematic and know that when you convert the schematic to PCB it will just work and then when you order the PCB and the parts from the BoM, all the right parts will turn up and will fit on the PCB. Searching a 'Light' library is fast and easy but leaves the grunt work to the user. Searching a 'Heavy' library is slow and but you can just place a part and it's done because the grunt workhas laready been done. That said you can build parts anywhere in between these two categories in EasyEDA. Our library searching and management is still needs to improve because there are so many user contributions, not all of which are built or documented very well. * In theory you could create little text files to tailor your symbols and simply paste them into the header sections of the EasyEDA Source files for your parts but that is very clunky and so quite error prone. Hence it's not a trick we recommend. :)
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