Christmas Star project

[tumbleweed]

When I do things like this where the routing is more important than a pretty schematic,
I prefer to have the schematic part symbol actually reflect the physical part. That way it's a lot easier to see what's going to cross, change layers, etc and lets you reassign the pins when you're doing the schematic.

It's nice to see all of PORTA shown together when you're doing the program, but that's not what the board is going to look like.
If the part shape resembles the physical part I find it's also easier when you go to checkout the board... no referring back to the datasheet to find out where the heck pin 15 is in that TQFP package.

 

[Visitor]

EasyEDA is a mixed bag in that regard and there's the never-ending debate about physical layout vs functional layout. But I do agree, I'd much rather see the physical layout when designing a circuit board.

For the temperature logger I've been working on, I used a PIC18F26K22 in the SSOP package. In the EasyEDA library, its symbol is in the functional style. But the 18F25K22 has a physical-arrangement style symbol. These are the same part, with different amounts of memory, so the pinouts are the same.

There might be a more direct way to do this, but I put the symbol for the 18F25K22 in my schematic then changed all of the info, including both the Microchip and LCSC part numbers to be the part I wanted.

Makes sense of course, but there are a lot of potential pitfalls in doing so, especially with the -4x parts since different packages have different pinouts. Since MrDEB may be having the boards fabricated, the risks (and frustrations) of suggesting he do the same are too great for me.

I don't really like the symbol for the 18F25K22 that much – it's needlessly wide. My schematic wasn't too crowded or I would have taken a couple minutes to edit the symbol.

 

[MrDEB]

I searched and found zip for editing the schematic symbol in Easyeda.
Diptrace is a piece of cake for editing the schematic symbol. Would be really nice to have the actual footprint in the schematic. Make life easier.
been editing my schematic to avoid too many traces crossing other traces. resorted to port tags to make reading the schematic easier to read.

 

[Visitor]

Where were you searching? Because editing symbols is simple, and you have the opportunity evey time you place a symbol.

It's hard to miss EDIT as it's right there next to PLACE.

Clicking EDIT opens up a new window with the symbol in it.

Click on a pin and drag it where you want it to go. Notice the physical pin number is right there by the pin. – you don't even have to look anything up. When you click and drag, be sure you've clicked on the pin itself and aren't just moving one of the labels.

You'll need to use the rotate and flip horizontal/vertical commands to get the pins oriented in the right direction.

Please note: My only association with EasyEDA, JLCPCB and LCSC is that of a satisfied customer. I haven't received any freebies or discounts beyond those given to every customer for my remarks here or anywhere else. I've had several boards made by JLC, and several more boards assembled there, all with good results.

I would hate for anybody reading about MrDEB's struggles to come to the wrong conclusion about EasyEDA without even trying it.

 

[MrDEB]

This is what I interpreted from post 41/42 disregard the leds etc Will look at schematic edit

 

[Visitor]

That's ....um..... interesting. What's it supposed to be?

It's not a schematic from EasyEDA, so you've given up on using this software?

If you've gone back to using Diptrace, I think you're going to have trouble supplying a correct BOM in the needed format as well as the centroid file needed for assembly. Good luck.

 

[Visitor]

Just as a point of order. To have boards assembled by JLC, you don't need to use their EasyEDA software. It will just make things simpler, and potentially lead to less errors and need for clarification.

What you do need to have JLC assemble boards:

¤ Standard Gerber and drill files. Differences in formatting, units, layer-naming conventions, etc., may result in delays.

¤ Components selected from JLC's library of parts for assembly. Any components not in their library simply will not be installed on the boards. Preferably, components will be selected from JLC's "basic" library to avoid extra setup charges.

¤ A BOM containing manufacturer, manufacturer's complete part number, LCSC's part number and reference designator agreeing with the schematic.

¤ A centroid file giving each component's location and rotation angle.

This is easy to do in EasyEDA. If someone doesn't have a good understanding of the above, generating the needed files may be difficult with other software packages.

JLC charges a $7 engineering fee for board assembly. Don't expect much hand-holding for that price! I've been very satisfied with the work JLC has done for me, but I do play by their rules.

 

[MrDEB]

I was experimenting with Diptrace and yes it will export the CPL file but the issue is having to draw the footprints for the components.
back to EasyEDA and edit the schematic as per post #44.
Was looking at and correcting my schematic (Easyeda) and thinking about what tumbleweed etc mentioned about the schematic footprints etc.
Hopefully get the design done in time for Christmas. And have decided to have everything on the top side of the board. Was planning on having the Pic and USB on back side.

 

[tumbleweed]

It was just a suggestion of how I do things... if it causes you too much grief then forget it.

I just find it hard to go from a "pretty schematic" to real life when trying to minimize routing issues
without having to draw things out by hand or guessing. Some folks are probably better at it than me.

 

[Visitor]

From the half-dozen pins I moved yesterday as a starting point, it took me 22 minutes to edit the symbol to the physical layout shown here. It's not difficult, and it's far quicker and easier than all the time MrDEB spends looking for short cuts and easier ways. Sure, you make a few fumbles the first time, but this is how you learn so it's easy to do next time.

This symbol for the pic18f46k22-I/PT, which has abundant stock for assembly, should show up in EasyEDA under user:jonchandler, but it may take a while to get through the system. MrDEB, message me your email address if you can't locate the file and I will send it to you.

This wasn't even creating a symbol - it was merely editing an existing symbol. I didn't need to look at the data sheet; all I had to do was move pins around. The hardest part was looking at the PCB footprint to verify the arrangement of the pins. If you start with something easy like this, if you ever need to create a symbol from scratch, you'll know what to do.

 

[MrDEB]

I found a 18f46k22 part # C89972. Didn't need to change anything.
Did find that doing the schematic this way was really easy and looks better.
Also discovered duplicate connections not needed and had to add one more resistor array and 4 leds
Will double check correct pinout but it should be good.

 

[Visitor]

It is always such a rewarding experience in my futile attempts to help you. For I am an idiot and will never learn.

 

[Visitor]

MrDEB, your "schematic" will work to build a board, and it's probably fine for what you're trying to do.

But it's not really a schematic, which should clearly show connections. Using your rather unconventional arrangement, you can't tell at a glance what's connected where.

Also, you missed another detail of making the board easy to lay out, as I suggested before. I assume white and blue LEDs will be more-or-less uniformly distributed (i.e., blues and whites spread across the board). For easier routing, most people would alternative the LED colors, and sort out in software which LED is what color.

A clear, concise schematic isn't difficult to make. This didn't take that long to do. I guess maybe you don't appreciate the art of the craft. A nice schematic and board layout is part of the reward of laying out circuit boards.

EDIT – BELOW IS AN INSET VIEW OF THE CYRSTAL I HAD INTENDED TO INCLUDE. USING A CRYSTAL IS MY PERSONAL PREFERENCE FOF REASONS.

 

[Pommie]

No LEDs sharing resistors? You've wasted 3 cent!

Mike.
BTW, thanks for getting me into easyEDA, it's very easy and intuitive to use.

 

[Visitor]

BTW, thanks for getting me into easyEDA, it's very easy and intuitive to use.

My old version of Eagle was getting pretty dated I tried Kicad and just couldn't wrap my head around it. I've looked at some of the other vendor-sponsored layout programs and found them lacking – either everything you did had to be public, or you could only have a handful of your own parts in a personal library or they require you to use their board fab. All unacceptable and not enough to lure me away from Eagle.

Then I tried EasyEDA. You can have an unlimited number of private projects, the library of components is huge and if you can't find what you need, you can easily add component symbol/footprints supplied by Digikey and Mouser. It truly is easy to use and after designing a couple boards with it, I decided to make it my go-to layout program.

There are a few idiosyncrasies to be sure and sometimes it takes a bit of experimenting to do what I want but overall, I'm truly impressed and happy with it.

Glad it's coming together for you.

 

[Visitor]

Should I explain to MrDEB that he needs some type of USB-B connector instead of the type A he has collected?

 

[Nigel Goodwin]

No LEDs sharing resistors? You've wasted 3 cent!

As each LED is individually driven by it's own I/O pin, then there's nothing to share

However, nice clear little diagram he's drawn.

 

[tumbleweed]

A few comments...

Put a cap on each set of VDD-VSS pins. A 0.1 ceramic right at the chip is fine.

Get rid of the LED on MCLR/RE3. That's an input-only pin even if you don't use it as MCLR.

You may also find that the LEDS on the ICSP RB6/RB7 programming pins are too much of a load for the PICKIT to program,
so if you can live without those two LEDs you'd be better off. I'd at least provide a way to isolate them from the LEDs just in case.

And finally... before you build this have you actually tested driving the blue and white LEDs you intend on using?
I'd be surprised if 470R would work well for both. I've had some blue LEDs that you can use several Kohms with
and are still bright enough to burn a hole in your eyes.

 

[dougy83]

This didn't take that long to do.

What's going on with RA6/7 in your diagram? Is there supposed to be a crystal there?

 

[Pommie]

As each LED is individually driven by it's own I/O pin, then there's nothing to share

I was comparing it to MrDEBs schematic in post #51.

Mike.