• Welcome to our site! Electro Tech is an online community (with over 170,000 members) who enjoy talking about and building electronic circuits, projects and gadgets. To participate you need to register. Registration is free. Click here to register now.

Jon's Imaginarium – SnapEDA PCB Symbol and Footprint Generator

Visitor

Well-Known Member
Whatever PCB layout software you use, there comes a time when you may have to create your own schematic symbol and PCB footprint. Even with with symbols & footprints provided by distributors like Digikey and Mouser, less-common parts may require you build your own.

SnapEDA provides symbols and footprints for many components, but I recently learned they have a tool to help you build a schematic symbol from the data sheet. You upload the datasheet and highlight the pin table, and their software uses OCR (Optical Character Recognition) to identify the pinout.

You need to scan the list to verify everything imported correctly (in the sample I tried, 'Input2' was misidentified as 'InputZ', so minor editing may be needed). The software attempts to determine if each pin is an input, output, power, gnd, etc. from the name of the pin, so you may need to help it a bit there too.

When the table is correct, click the button and you are quickly rewarded with the schematic symbol and standard PCB footprint as identified from the data sheet. If the footprint is non-standard (i.e., not a standard IC footprint), you'll still have to do that yourself (but I'll bet they are working on that too!).

Download the newly created library package in most layout package formats, and you're good to go. EasyEDA users are reminded that EasyEDA imports libraries in several formats, including Eagle.

This package presents the symbol in a functional arrangement rather than a physical one – inputs on the left side of the chip, outputs to the right, power at the top, ground at the bottom. I don't know if there's an option to select the type of layout. Interestingly, they say from their results that users are just about split down the middle in their preferences for the arrangement.


As a note: SnapEDA will make custom symbols and footprints for you for around $30 – if you are designing circuit boards for a living, this may be a worthwhile investment. Your time may be better spent elsewhere, and you get a verified symbol and footprint designed by a professional.
 

Visitor

Well-Known Member
I used the software to create a symbol for an LM324, one of the examples they suggested. It's something they did suggest, but the end result was entirely my doing. I uploaded a datasheet, selected the pin table, edited the OCR data and downloaded the result. Pretty simple process. And I should emphasize, this is a free service they provide. In fact, component libraries for many components are also free. It's only the service where they custom create a library for a component that there is a charge.

Personally, I don't mind creating a symbol and footprint for a component when I need to. I'm not sure why people find it to be an impossible task, and spend more time searching for a library than it would take to build one from scratch. The SnapEDA tool just relieves the tedium of typing pin names and laying out the symbol.

I'll use the tool and post pictures of the process shortly. I should have done this last night, but I was kind of excited by this neat tool.

I learned about this tool from Amp Hour Podcast #531 – Footprints and Symbols with Natasha Baker. Natasha is the creator/founder of SnapEDA with an interesting story to tell. It's worth a listen.
 

Visitor

Well-Known Member
Turns out this is a beta version that's been around for some time. I couldn't find a link for the InstaBuild software – every reference I could find led to a page of hype extolling the virtues of the free service, available to everyone, and links to build three suggested parts.

I asked SnapEDA where to find this tool. The response is that it's available for components "where it's known to work and we have a verified footprint." If it's known to work, then a symbol for that component already exists, so ..... I think this idea has tremendous potential, but it's not quite ready yet.

I did try to spoof the system to create a symbol for XR21V1414 4-channel USB/UART chip I was looking at and ran into an immediate issue. This is a 48 pin chip, and the pin table spans several pages in the data sheet. The InstaBuild tool choked when I attempted to add the second page of the pin table. Any chip when it's worthwhile to use this tool probably has a pin table spanning several pages.


This did stir some thought processes however. This tool uses OCR to read the pin table. PDFs are usually text-based; copying and copying the text directly would eliminate the possibility of errors introduced by the OCR process. Not that copying text from a table is a trial task! Once you have the pin number and name captured as text, generating a schematic symbol, or at least the appropriate pins could be done with some simple software.*

*Simple for some, left as an exercise for the reader ;)
 

Latest threads

EE World Online Articles

Loading
Top