Author Topic: What are some good rules of thumb for making clean schematics.  (Read 6819 times)

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Offline dsharp02

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I've been playing around with EasyEDA, and I like it a lot.  However my schematics are a mess.  What can I do to clean things up?

I've attached a copy of one of my schematics for reference.

Thanks,
Dave

 

Offline mrpackethead

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Re: What are some good rules of thumb for making clean schematics.
« Reply #1 on: July 04, 2017, 05:57:17 am »
what in particular makes you think its a mess.
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Online RoGeorge

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Re: What are some good rules of thumb for making clean schematics.
« Reply #2 on: July 04, 2017, 06:04:52 am »
One step would be to use the GND and VCC simbols instead of drawing the power wires.

Offline ataradov

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Re: What are some good rules of thumb for making clean schematics.
« Reply #3 on: July 04, 2017, 06:11:56 am »
All power lines have to be changed to power symbols, that's for sure.

I also use broken lines with labels on each end for lines that are too long and go all over the place. Example: https://github.com/ataradov/free-dap/blob/master/hardware/d11_usb_mini.pdf
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Offline AG6QR

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Re: What are some good rules of thumb for making clean schematics.
« Reply #4 on: July 04, 2017, 06:14:44 am »
That's actually not bad.  The rules I hate to see violated senselessly are those that say: Power at the top, ground at the bottom, signals flowing from left to right.  But you respected those rules.  As RoGeorge points out, you could use symbols for power and ground, especially where you feed them into the ICs, to eliminate a bit of clutter. 
 

Offline tautech

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Re: What are some good rules of thumb for making clean schematics.
« Reply #5 on: July 04, 2017, 06:48:09 am »
That's actually not bad.  The rules I hate to see violated senselessly are those that say: Power at the top, ground at the bottom, signals flowing from left to right.  But you respected those rules.  As RoGeorge points out, you could use symbols for power and ground, especially where you feed them into the ICs, to eliminate a bit of clutter.
Yep it's neat enough but as each has said assign the GND and VCC nets and use net labels for connectivity that the package should sort out for you. You should be able to make the IC power pins invisible and the package just know that need connectivity when you come to the PCB layout.
The 75440 for example could have those 4 GND pins linked at the IC and either just one connection to GND or add a power net connection signifier and let the package sort it out. For this to work seamlessly the IC pin need have exactly the same name as the power net.
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Online CatalinaWOW

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Re: What are some good rules of thumb for making clean schematics.
« Reply #6 on: July 04, 2017, 01:29:05 pm »
Generally not bad.  One rule you haven't totally followed is to make the signal flow dominant.  Changing supplies to bus type connections as others have suggested will go a long ways toward this.  Move your input connectors to the far left of the page, and label the actual signal pin (pin 2) as signal.

Another minor changes would be to come up with a short name for the input connector type.  The mind equates area with importance and this name occupies space totally out of proportion to its actual importance.
 

Offline Gyro

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Re: What are some good rules of thumb for making clean schematics.
« Reply #7 on: July 04, 2017, 03:18:00 pm »
I've just spotted the wires crossing and joining on the diodes at the right hand side of the schematic, that's a definite No! Wires should either cross, or join (T-junction style), but never join on a cross.

Nip the habit before it sticks.  ;)

EDIT: An excellent example of why you don't do it is the misplaced connecting dot on the wire going to U1, pin 13. Do that on a cross and you'll be in a mess.
« Last Edit: July 04, 2017, 03:26:35 pm by Gyro »
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Offline rstofer

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Re: What are some good rules of thumb for making clean schematics.
« Reply #8 on: July 04, 2017, 04:28:18 pm »
You have duplicated the power and ground connections on the op amps.  I guess using power and ground symbols would remove a bit of clutter but, overall, I like it.  The power rails are in the right place, the logical flow is left to right, I don't have any heartburn with the dot connections but I do have a problem with the abandoned dot U1-13.

I don't really have a problem with the diode connections.  It clearly shows the intent.

Overall, I like it!  It's better than most of mine!
 

Offline TheUnnamedNewbie

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Re: What are some good rules of thumb for making clean schematics.
« Reply #9 on: July 04, 2017, 04:42:13 pm »
If we are going to nitpick, I prefer putting stuff like pullup resistors, decoupling capacitors, etc. close to the device they are pulling up for. Examples here would be C1 and C2, R4 and R5.

Also, I like when people group stuff. Net lables should be used sparingly - none of this "IC pin to netlabel stuff". I myself am still undecided if I like conectors to be the start of the "signal" or send the signal from the connector straight to a netlabel, and then start the netlabel somewhere else.

I'll upload some pictures later when I have time.
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Offline ataradov

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Re: What are some good rules of thumb for making clean schematics.
« Reply #10 on: July 04, 2017, 05:30:50 pm »
I've just spotted the wires crossing and joining on the diodes at the right hand side of the schematic, that's a definite No! Wires should either cross, or join (T-junction style), but never join on a cross.
I din't personally see anything wring with this. Plus in this case the intent is very clear, and doing things otherwise will create more mess.
Alex
 

Online schmitt trigger

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Re: What are some good rules of thumb for making clean schematics.
« Reply #11 on: July 04, 2017, 07:02:04 pm »
Your schematic is actually very decent.  :-+

Other posters have already made their (good) comments, I won't repeat them.

Thus I'll only add that some times in very tightly drawn schematics, when one has several identical devices clustered together, it helps to do a global description like:
"D1 thru D8: 1N4007"
instead of listing each device:
"D1 1N4007"
"D2 1N4007"
"D3 1N4007"
and so on............

It may not matter on a short name like 1N4007, but nowadays some components have humongous part numbers, and it adds to visual clutter quickly.
« Last Edit: July 04, 2017, 07:04:35 pm by schmitt trigger »
 

Offline Len

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Re: What are some good rules of thumb for making clean schematics.
« Reply #12 on: July 04, 2017, 07:31:06 pm »
I've just spotted the wires crossing and joining on the diodes at the right hand side of the schematic, that's a definite No! Wires should either cross, or join (T-junction style), but never join on a cross.
I din't personally see anything wring with this. Plus in this case the intent is very clear, and doing things otherwise will create more mess.

I agree with "definite No!" I've seen schematics where crossed lines are sometimes connected and sometimes not. Or where it's hard to read whether there's a connection dot on the crossed lines. So I think it's good practice to never have crossed lines that are connected. I don't find this to be messy at all.
 

Online tggzzz

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Re: What are some good rules of thumb for making clean schematics.
« Reply #13 on: July 04, 2017, 08:17:48 pm »
General points...

Signal flow left to right and top to bottom, except for feedback paths.

Signals connected together should have a line between them; if you don't, how can you be sure that you have spotted everything on that net?

Many common "design patterns" (e.g. op amp integrator, or op amp current source) are traditionally drawn in a certain way. If you have such a block, draw it in the conventional way.

Circuit diagrams are read far more often than they are written, and are read by people that don't know the circuit in intimate detail. Draw whatever is necessary to allow other people to understand the circuit's intended operation.
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Offline dsharp02

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Re: What are some good rules of thumb for making clean schematics.
« Reply #14 on: July 04, 2017, 09:57:00 pm »
Thank you all for the advice.  I've tried to follow everyone's suggestions, and I have attached the result.  If you still see room for improviement, let me know.

Thanks,
Dave
 

Offline ataradov

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Re: What are some good rules of thumb for making clean schematics.
« Reply #15 on: July 04, 2017, 10:02:20 pm »
I like it. To me this is much more readable than the first version.

One note though: if you export to PDF, make sure that it is searchable. Those lose ends turn into total nightmare on a multi-sheet schematic without ability to search.
Alex
 

Offline ruairi

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Re: What are some good rules of thumb for making clean schematics.
« Reply #16 on: July 04, 2017, 10:29:13 pm »
I'm far from an expert but on a simple schematic like this breaking everything into sub sections is making things less clear for me, I like to see how the signal flows without having to make mental leaps (I could be in the minority).

I'm loving the thread though, some great ideas.



 
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Offline tautech

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Re: What are some good rules of thumb for making clean schematics.
« Reply #17 on: July 04, 2017, 11:03:50 pm »
Thank you all for the advice.  I've tried to follow everyone's suggestions, and I have attached the result.  If you still see room for improviement, let me know.
There is, ~1/2 way between your two versions.

For this design there is little need to break the schematic into each of the functional blocks, for higher density and more complex multi-sheet designs it's a good idea.
Firstly get rid of the multiple VCC paths to each part of the IC, sure show it on one part, you pick which.
You've got the other VCC's and Gnd's right.  :-+
Either C1 or C2 can be omitted, you don't need that much capacitance on each VCC pin....why 100uF ? Misprint ?
If one is a pull-up only then there is little need for capacitance on it.



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Offline ahbushnell

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Re: What are some good rules of thumb for making clean schematics.
« Reply #18 on: July 04, 2017, 11:27:38 pm »
Nice

Flip R3 vertically.
 

Offline dsharp02

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Re: What are some good rules of thumb for making clean schematics.
« Reply #19 on: July 04, 2017, 11:30:45 pm »
There is, ~1/2 way between your two versions.

For this design there is little need to break the schematic into each of the functional blocks, for higher density and more complex multi-sheet designs it's a good idea.
Firstly get rid of the multiple VCC paths to each part of the IC, sure show it on one part, you pick which.


I tried connecting VCC and GND only on op-amp 1.1 but the PCB software seemed to have issues with it.  I ended up with wierd issues where the GND pin of the LM324 wasn't connected to anything.  So my work-around was to connect every op-amp to both VCC and GND.

Either C1 or C2 can be omitted, you don't need that much capacitance on each VCC pin....why 100uF ? Misprint ?
If one is a pull-up only then there is little need for capacitance on it.


Pins 8 and 16 provide the power for the h-bridge on left and right side of the chip respectively, so I put in caps for those pins, not for the pull-ups.  As for why 100uF, it was just a number pulled out of thin air. :D  I used the same amount for C3 to minimize the number of different parts.

Thanks,
Dave
 

Offline tautech

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Re: What are some good rules of thumb for making clean schematics.
« Reply #20 on: July 05, 2017, 01:02:09 am »
There is, ~1/2 way between your two versions.

For this design there is little need to break the schematic into each of the functional blocks, for higher density and more complex multi-sheet designs it's a good idea.
Firstly get rid of the multiple VCC paths to each part of the IC, sure show it on one part, you pick which.


I tried connecting VCC and GND only on op-amp 1.1 but the PCB software seemed to have issues with it.  I ended up with wierd issues where the GND pin of the LM324 wasn't connected to anything.  So my work-around was to connect every op-amp to both VCC and GND.
Gotcha.
If there's any discrepancies in the net names it'll probably spit the dummy, recheck assignments and names.
You can get caught out with these, some devices call their power supply VCC and other VDD. To reduce the chance of error I how rename all power nets to +5, +12 or whatever.
This is a pretty basic requirement of PCB software and I after checking the IC pin power assignments are correct make the power connections to the IC invisible. (not shown)
It makes for a much tidier layout.

I'm no real expert, much of what I've learnt has been through some little experience and is primarily based on mimicking the beautiful schematics of yesteryear. Grab some service manuals of test equipment and study the layout formats used in those schematic.
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Online CatalinaWOW

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Re: What are some good rules of thumb for making clean schematics.
« Reply #21 on: July 05, 2017, 02:18:44 am »
Good job.

You are on a tough boundary as far as breaking this thing into subsections as you have in your second effort.  As a couple have commented the circuit is not complex enough to normally warrant this.  But it eliminated a lot of criss-crossing wires which is a big positive. 

Some schematics can have a lot of components with very little crossing topology.  Others turn to spaghetti with just a few.  There is no single rule for them all.

At this point, pick what works best for you (and the rest of your team if you are working in a group situation).
 

Offline Audioguru

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Re: What are some good rules of thumb for making clean schematics.
« Reply #22 on: July 05, 2017, 03:04:08 am »
Can't the grid in the background be turned off?
 

Offline jh15

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Re: What are some good rules of thumb for making clean schematics.
« Reply #23 on: July 05, 2017, 04:48:59 am »
i like that you are using the "common" symbol rather than the ground or earth symbol.

Funny everyone here is saying "ground".

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Online tggzzz

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Re: What are some good rules of thumb for making clean schematics.
« Reply #24 on: July 05, 2017, 06:16:59 am »
Thank you all for the advice.  I've tried to follow everyone's suggestions, and I have attached the result.  If you still see room for improviement, let me know.

Without connecting lines, how do I know I've spotted everything connected to IC3 pin 6? Arguably it is possible on this small diagram, but it becomes impossible on larger diagrams.

Consider scalability of your approach; for larger circuits, have hierarchical diagrams. Each diagram then shows a separate conceptual subsystem, e.g. analogue input, motor driver, controller, and there is a higher level showing just the subsystems and their interconnections. Analogy: in software you have a main() function which calls other functions, such as the pseudocode
Code: [Select]
controlMotor() {
  setPoint = readVoltage1();
  position = readVoltage2();
  correction = pid(setPoint, position);
  pokeMotor(correction);
}
int readVoltage1() {
   ...
}
int pid(int sp, int p) {
   ...
}
etc

How does the grid aid understanding? It doesn't, so delete it.

The schematic serves two purposes: to help engineers and technicians, and to generate a netlist. Sometimes those purposes conflict, e.g. with having "too many" power connections. Where necessary, have multiple different names, e.g. AGND and DGND.

"Generic" decouplers, especially for digital ICs should be grouped away in a corner, since they don't aid understanding and during layout are "sprinkled" across the PCB. OTOH, decoupling arrangements for analogue ICs are often shown on the schematic next to the relevant IC.
There are lies, damned lies, statistics - and ADC/DAC specs.
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