Library/Components/Symbols Sharing discussion

Is there any video or written tutorial on DesignSpark PCB?

I am just starting working with it on my new job -

any help apprciated

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typing test http://wpmtypingtest.org/

"I tend to use Default.stf and Metric.ptf for schematic symbols and pcb symbols respectively."

Can these be attached to the design at a later stage?

@Frank

I agree that limitations of other cad programs should be observed. Being able to use either or will be infinitely useful for sharing of ideas. If a file is in any format it can be used by DS and if needed DS should be able to export to something usable by other options as well. This would bridge the gap between die hard users of one or the other and give common ground to innovation.

@Dragonlaird

Number three is partly what Ive been hinting at.  With PCB services (Laen comes to mind) being so cheep to make a board , DesignSpark making PCB files easy to work with, and an explosion of open source hw/sw It should be a couple  clicks to make something.Order parts, Order PCB's etc.

It shouldnt infinitely complicate the process if I had to use another cad program before or after DS, or if for what ever reason ordered parts from another supplier.  The point is make the program usable for every one.  Get more people making things.

For my two-penneth worth, anothr couple of suggestions:

1. Try to populate as many component values as possible, such as the corresponding RS part number and datasheet URLs - It's not too difficult to find a part on RS but it's so much easier when you have the link/part already included.

2. Do NOT hide power/ground connections as they are sometimes used by other parts to turn on/off components, either by manual or automated means, for power saving (green) techologies.

3. Add a facility to the site to allow uploading of custom libraries with a search/download facility - Even better if the parts can be selected online allowing a new, custom library to be downloaded with just the selected parts in it (although I suspect some will always want to download the entire set).

Slightly more towards improving the app rather than sharing libraries, another couple of points:

4. Use some standard nets/classes for power/ground pins to allow simplified auto-connection when dropping a symbol onto a schematic.

5. Add a feature to equate a schematic net class over to the PCB design, e.g. If I create a class called VDD and give it a with of say 5, I want it to be carried over to the PCB upon initial creation/routing to distinguish it from a typical signal class with a small width.

Just some food for thought...

Dragonlaird

Not to get too off topic, but some of this will make more sense if you determine if the standards you are looking for apply specifically to DesignSpark or might encompass other tool sets.  Certainly if you have to include the limitations of other tool sets some of your standards will need to take into consideration the limits and enhanced capabilities. 

For instance, using IPC naming standards for footprints works..... sometimes.  Some tools do not support a long enough name to include some of the large names IPC demands.  The same is true with manufacturer part numbers.  Although generally these fit in most cad tools well, some manufacturers insist on using characters that are not well recieved by all tools.  We see characters like "/", "\" and "#" all the time.  And of course for tools that use the operating system to represent the componets this causes no end of heartburn.  However dispite this I agree that all components should be represented by part number.

I agree with the consensus that all pins should be shown and that there should not be hidden pins.  Hidden pins are the largest source of schematic errors that we see in the design services business.

Top down parts are probably the norm as stated for smaller pin count parts.  They are certainly easier to enter and collect data for in this format.  There will always be exception to this rule, and generally large pin parts will need to be re-organized if they are presented top down.  We generally also limit the size of symbols to no more than 100 pins, breaking them part if they get larger than this.

Using a template style creation method, whether doing this by pulling up an existing part or using a system like ours, will allow all attributes that are required to be available, as well as appropriate text sizes and justifications.

I also think that all pins should be on grid.  Aditionally we build the point of origin on the top left pin so that pins will always fall on grid properly.  Some tools will not accept a center point for the symbol, and even those tools that do accept a center point can accidently offset the pins off grid if the center of the symbol is not on a grid (odd grid width or height rather than even).

Here are some points I would mention in the  guidelines:

1. A CAD schematic is a manufacturing document that defines how a circuit board will be made. Don't confuse that with a circuit diagram, which explains how a circuit works.

2. Off board parts like jacks and pots do not appear as schematic components because they are invisible to the CAD system. Instead, place the symbols for a connector or connection points to take the  wires that run to the off-board points. Next to the connector you can place text or even draw a simple non-component jack or pot using the schematic line drawing tools.

3. No hidden power or grounds. That way a schematic "reveals all" even to a beginner.

4. Top down symbols are OK for small ICs, say 14 to 18 pins maximum, and hobbyists prefer that. For chips with ports and busses, you need to group pins by function. Multi-part chips must group pins with each section. Opamp pins are organised by function.

5. Every component is an actual manufacturer's part number. For example, a BC557 transistor. Generic parts like "NPN" or " PMOS" lead to unknown footprints and pinouts. So a good library has lots of transistor and SCR part numbers. This is valuable to hobbyists who want to place the exact part number they see on a parts list.

6. Good footprint info at: http://www.toplinedummy.com/drawings/login.cfm and package names at: http://www.topline.tv/SMDnomen.pdf.

I think the comment on the original thread , brought up some really good points. I will repost them.

1. Symbols need to be in proportion and to a useful scale. I can't place your enormous transistor symbol beside somebody else's tiny IC.  Some hobbyists fill a schematic page with just a few gigantic symbols.

2. Symbol IC pins must be on grid - the same grid - and with the same spacing intervals.

3. Pin labels should probably be taken from a manufacturer's datasheet and not be invented by the  creator.

4. Are power pins hidden or explicit?

5. Are pins placed like a top down view of the IC or are they grouped by function?

6. Symbol style.