finishing project, smart way to do bus

Go To Last Post
15 posts / 0 new
Author
Message
#1
  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Hello,
I am finishing my project a I would like to create PCB.

In Eagle, there is a possibility to draw a bus. This is nice. And now I would like to create bus that will be wired by the most natural way by autorouter, such that the wires(paths) wouldnt "cross each other". It is bus for 7 segemnt display, so I could easily define pins in source code. I dont care if PA0 connect to segment A or B for example. It would be better to do layout at first.

Picture is not that important..

How to do it?

Regards
Lukas

Attachment(s): 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Don't use the autorouter is my suggestion. Do it by hand like most of us would.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Any PCB design for an eight 7-seg LED display with six momentary push-switches, five LEDs, a display controller 40-pin IC, a ribbon-cable heade, and (possibly) an Arduino board is going to be a big undertaking.

Assume that you are going to be putting the final assembly into a plastic enclosure. So the PCB for the circuit needs to be designed around the enclosure box. PCBs are priced by the number of square inches and not by the complexity of the circuit inside the square inches. Can you get the 40-pin IC in a smaller package such as quad flat-pack? And, can you use smaller 7-segment displays that perhaps don't fit on a 0.1" spacing breadboard? This will save a lot of cost for the individual PCBs.

How many of this circuit are you planning to make? One or two? Ten or twenty? Ten or twenty thousand? The projected design quantity also goes a long way in determining the various PCB design trade-offs.

This design on the breadboard photo could be done on a single-side PCB with few difficulties.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

From your prototype, that should NOT be a board that needs autorouting.

The most important concern is to simply layout the components effectively. This will be far more important to reducing crossovers. And, if not laid out effectively, then even the autorouter cannot do a reasonable job.

In about 10 years with EAGLE, I have never used the autorouter and I have no intention of using it.

Jim

 

Until Black Lives Matter, we do not have "All Lives Matter"!

 

 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I can't answer your Eagle question, but a suggestion would be to put the crystal as close to the crystal pins on the micro as possible, don't connect it via long wires to another breadboard.

You may have erratic operation with the crystal where it is on your breadboard layout, and then you don't know if the problem is hardware or software.

Also, for your PCB, be sure to put the crystal very close to the micro's crystal pins.

JC

Attachment(s): 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Thanks for tips,

The XTAL, I will definitely do it.

The main problem is that only PCB development method available to me is to do it with alcohol-fix on one side board. This like: http://upload.wikimedia.org/wiki...

Edit: Everyone is advising me to do it manually but how when I need to define connections in schematic, (fixed connection in schematic), ex. "PA0 i connected to segment A, PA1 i connected to segment B". When I switch from the schematics to board I see that by switching connection of segments A and B paths would be more simple for paths, and easy to do in code. But when I try it rewire, "Please do it in schematics." msg appears.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

auto routers don't work with 1 side boards

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

???

Attachment(s): 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

I use Eagle and IF your PCB parts placement is simple enough and they have enough space between them, I've found the autorouter can do it. Read your user guide for how to work the autorouter and give it a try. IF it doesn't do it first time...do it manually.

1) Studio 4.18 build 716 (SP3)
2) WinAvr 20100110
3) PN, all on Doze XP... For Now
A) Avr Dragon ver. 1
B) Avr MKII ISP, 2009 model
C) MKII JTAGICE ver. 1

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

ok
I mean they don't do a good job.
you often end up with a lot of 0 ohm on the top side.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

If the autorouter is good for simple project only, then it is useless. If it is simple, then it is simple to do it manually. The only algorithm known is probably only O(k^n), I think. When using dual-side PCB with via holes, we have more space for possible solution, if I understand well.

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

...

Attachment(s): 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

Autoroute does not work well:

Attachment(s): 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

In Eagle, you make CONNECTION changes on the schematic. They will automatically be reflected in the board if the board is open at the same time the schematic is.

That part is dead simple.

On auto-routing: it DOES have its place. But, truth be known, it works best either for very simple boards or for very complex ones. The reason why auto-routing is discouraged for simple boards is that if you do that, then you don't learn the skills that help you make good boards. snigelen & maksim's example, above, shows why auto-routing is often less than optimal, even for simple boards.

From the layouts that I see above, you would be helped by learning how to do ground flood.

Another hint: lay out the parallel bus first. then, fit everything else around it, Don't be afraid to move parts. Don't be afraid to change mcu pins that drive single-function (not parallel bus) lines. Its all part of making a board that works.

Another hint: board layout is a lot "engineering", but its also a lot "art". There is no one right way. Nor even one "best way", There may not even be a "best way". The way that gives you predictable desired operation is the way that works.

Jim

 

Until Black Lives Matter, we do not have "All Lives Matter"!

 

 

  • 1
  • 2
  • 3
  • 4
  • 5
Total votes: 0

maksim wrote:
Autoroute does not work well:
I didn't say it worked well. I said that it worked (without words ;-)).

And if you use it (I usually don't), it's easy to afterwards do the changes you did.