Problem with autorouting in eagle..!

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Im using eagle 5.7.0 light version for windows. I made this line follower circuit, uc atmega328, l293d chip, voltage regulator ic, the circuit is this simple, still i cant finish autorouting.. Please help..!
heres the schematic..

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So what does Eagle have to do with AVR's? I am sure there is an Eagle Forum or at least post it in the General Electronics area!
Perhaps wait for a Moderator to shift it, before starting another one.

Charles Darwin, Lord Kelvin & Murphy are always lurking about!
Lee -.-
Riddle me this...How did the serpent move around before the fall?

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Autorouting is an excellent way to produce never working pcbs.

Peter

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seriously, I had a hard time choosing the right forum section to post my query. :S Now should i post this in general electronics?

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One of the Moderators will probably shift it. There is also a eaglecad group on YahooGroups.
Tried to open the attached file, but it is neither in .zip or .sch format.

Charles Darwin, Lord Kelvin & Murphy are always lurking about!
Lee -.-
Riddle me this...How did the serpent move around before the fall?

Last Edited: Tue. Mar 1, 2011 - 07:59 AM
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It may go to off-topic. I have Eagle too and you have to accept the FACT that an auto-router sometimes fails to hit 100% even on simple ( to us ) layouts and there's usually nothing you can do about it. I got to the point of just NOT using it. Or let it do its best and YOU finish up.

Your best option if you don't believe me is call Cadsoft and see what helpful advice they give you to improve it to 100% ( it may work for your specific layout, but generally I know what I'm talkin' about with its 'router ).

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

Last Edited: Tue. Mar 1, 2011 - 09:49 PM
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Quote:
I have Eagle too and you have to accept the FACT that an auto-router sometimes fails to hit 100% even on simple ( to us ) layouts and there's usually nothing you can do about it.

Agree...

Have to manual re-route.
Also you could used pad to jumpers the unfinished routes.

I'm using Eagle too.

Jeckson

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No professional PCB designer I know use autorouting, and they use much more expensive layout tools than Eagle. They might have used it for simple designs, but then it's so simple its just as fast to do it by hand :-)

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The eagle autorouter is horrible, freerouter is a lot better.

http://www.freerouting.net/index...

But beware if you use ground pours, freerouter does not consider it at all, so you may end up with unconnected ground areas after the route, that needs correcting in eagle.

(Click ratsnest untill theres nothing to do, use zoom-unrouted script to find the small ones)

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To get a working layout, you must tell the autorouter all the routing rules, which you have into your brain.
E.g. which wires may have which which resistance, which voltage to which others, which current, which voltage drop and so on.

A men need only less than a second to see, if a wire was critical in which parameter and to which other wires and change width and clearance accordingly.
But writing down a rule accordingly may cost minutes.
So writing down all the needed rules may cost more time than routing by hand.

Also a special problem was the topology, e.g. a big output current on the GND plane may not flow over the same wire as the input voltage.

Peter

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Sorry Patrick, wasn't talking bad about Eagle. My friends might have used the autorouter on simple designs. But as Peter just wrote it takes quite some time to configure it, so it's just as fast to do the routing by hand. And my point with the more expensive tools was that tools you are paying alot of money for (and for some of the tools I really mean alot) have an obligation to work better than the free ones. But nobody seems to trust the expensive autorouters either.
As far as I know Eagle is a decent tool.

-Jan Egil

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Thanks guys for helping me out. I manually routed with some help with auto router as well.. Im a total newbie at this and not pretty good at soldering as well, so please have a look at the layout and tell me if this is okay.
thanks

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How wide are those traces ?
Looks like there is plenty of space to upgrade them, or at least the power.

Is this for a home etch or real pcb ?

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width of the trace is 16mm.

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Is this for a home etch or real pcb ?

Yes im making a real pcb for my line follower robot, if thats what you asked.

Is there any chances that the board wont work?
thanks.

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I think you mean mil, not milimeter (16mm=630mil, 100mil=standard 2.54mm spacing)

If the connections are correct and the etch goes well, then it will work (if the required current is below what your traces can handle).

I would use atleast 24mil for signals and 50mil for power if its a home etch, since you dont have soldermask to protect the traces.

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Thanks for the heads up. Shall change it. :)

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Powers runs need to be much wider.
Motor runs need to be much wider.
Crystal needs to be close to micro, the runs from crystal need to be short.
The caps need to be close to the crystal, also with shorts runs.
The ground side of the caps need to run directly to the ground on the micro, don't share the path between caps and micro with other devices.
No programming header?
Why do you have the resistors so far away from their LED's? You have a lot of copper looping all over the place for those paths.
Why is one resistor mounted axial and the other flat?
No pullup on reset.
Should your sensor header also have power and ground on it? How do the sensors reference a common ground?

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No programming header?

I already have an arduino board, so i though i could program my uc using that and then put it in pcb.
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No pullup on reset.

same reason as above, i could reset the chip using the arduino board.
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Should your sensor header also have power and ground on it? How do the sensors reference a common ground?

the sensors take power from J6 on the board.
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Why is one resistor mounted axial and the other flat?

sorry, i dint get you..

Others i have cheanged their positions such that i could make traces, will make those above told changes.
thanks

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I would also avoid 90deg turns in traces, especially when etching.

Ground from the crystal caps going underneath the motor driver is also a very bad idea.

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Quote:
Why is one resistor mounted axial and the other flat?

sorry, i dint get you..


One is standing up, the other is lying down.

"Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it"

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Make sure the analog grounds only connect to digital gnd. at ONE point. Motor traces as far away from digital lines as you can get them.

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

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Unfortunately the board has many problems and funnies:
- The rightmost trace from the Mega to the LM293 fall off the board
- The trace from the mega via R7 to LED L looks to me like an odyssey
if you use / mode R7 intelligently you can shorten it by 70%
- The 7805 is to far from the edge to be mounted vertically and attached
to a heatsink or metal housing and too close from it to be laid flat
- The connectors are sprinkled across the board instead of lined up
nicely along the edge
- R7, even though shown as flat will probably not fit as the holes are too close
- There are no mounting holes for the PCB
- It looks to me like you are supplying power from Power3 to the pushbutton and
from there to the input of the 7805. Do you want to rest your finger on the
pushbutton all the time while the device is operating ?

I'm really sorry, but there are tons of problems, I doubt the thing will fly as it is. Why don't you publish the whole thing (attach the schematics as image and zip up all files in the eagle project folder). You should also provide a description what the project should accomplish.

You'll get help !

Markus

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Thanks for all the replies, i really appreciate it..

Quote:
It looks to me like you are supplying power from Power3 to the pushbutton and
from there to the input of the 7805. Do you want to rest your finger on the
pushbutton all the time while the device is operating ?

Actually i thought the switch would stay on once you press it.

My circuit is a line follower robot, it uses 4 infra red sensors which takes power from J6 connector, analog input is fed into the SENSORS connector. Ive not put a program header coz i have an arduino board which i could use for programming the chip. I kinda deleted the other connectors in the digital ports, the reset button, so as to make tracing easier(since i had arduino, reset button in my pcb wont be necessary)..

Please have a look at the schematic...

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The schematics don't look that bad. There are thing to add or to verify:
- Replace the pushbutton s2 with a switch, or leave it out completely
- Add a some 10nF caps to Vcc and Avcc (will have to be close to the chip on the PCB later)
- Verify the pinout of the L293D, It does not match what I see on the datasheet at st micro
- You might not need the reset button (power-on reset may be sufficient)
- You may like additional buttons wires to spare pine (like ISP pins) for future use, you don't actually need to add them in if not needed
- You may like additional LEDs wires to spare pine for future use
- You may want to wire the enable input of the L293D to a PWM output pin, allowing you to use PWM later for slow motion
- Define the size of the PCB you really want, I think you can get away with half the original size
- Define where on the PCB you want the connectors for ease of wiring and ease of access
- Define where on the PCB you want mounting holes to attach is safely to the robot

There are many things, if thought out beforehand, add no cost to a PCB, but make it flexible and future-proof.

Do you have a AVR programmer in any form or shape or think about getting one. Then add an ISP header, you don't need to use it.

Markus

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Before you start auto route, lay a thickish track right around the periphery of the board & rename it ground.
Orient connectors around the board so that they will be close to this earth track.
When the auto router starts it will connect to this track.
The track is also a handy place to attach oscilloscope & logic probe earth leads.

Charles Darwin, Lord Kelvin & Murphy are always lurking about!
Lee -.-
Riddle me this...How did the serpent move around before the fall?

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Another thing that's going to need fixing. C4 is labeled as a 100uF capacitor, but the board layout is for a small ceramic capacitor. It's unlikely that a 100uF capacitor will fit into that space on the board. You'll probably want to change the package size to one that will fit the capacitor. C5 is going to have a similar problem.

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I note that you have an indicator on the ISP SCK line. My suggestion is that it certainly is not required for ISP, so it is a good idea to have nothing on the ISP line when programming lest it causes problems with ISP.
This will avoid future posts such as.

Quote:
Help, ISP does not work

Charles Darwin, Lord Kelvin & Murphy are always lurking about!
Lee -.-
Riddle me this...How did the serpent move around before the fall?