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First eagle board....would someone mind checking?


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I've used eagle to map out circuit diagrams, but this is my first time building a board up to be fabricated.  The board is a simple bidirectional logic level converter with a buck/boost converter so I can run 5V sensors off of the launchpad (and everything else not-arduino).

 

I've spent some time reading tutorials and design guides and followed as many 'best practices' as I could remember as I worked, but would someone mind just glancing at it and telling me if I did something glaringly bad?

 

Thanks in advance

shifter.sch

shifter.brd

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You are missing all vias. Place them where the Xs are. JP2 missing connection. Lots of other tracks that are not connected all the way (yellow lines.) REG711's pin 4 on the schematic is not connecte

When you connect tracks to pins of a package that is not using your grid measurements, you should start the track from the actual pin, that way it is centred exactly on the pin and you move out from t

It will add them automatically if you use the net tool, do not use the wire tool unless you are manually connecting something it doesn't ratsnest for you.   Tapatalk Mobile Device    

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When you connect tracks to pins of a package that is not using your grid measurements, you should start the track from the actual pin, that way it is centred exactly on the pin and you move out from there.  If you are going pin to pin, start from one pin, go half way, and then restart on the other pin and connect in the middle.

 

Usually you don't need a 5v level shifter for I2C.  Since it uses pullups and just sinks current you can use 3.3V pullups and it will work with 5V devices.

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Datasheet for reg711 suggests surface mount ceramic for all of the capacitors to avoid ripple.  It's just a suggestion, not a requirement, but since you are already doing smt board, you might as well just take the plunge and go all SMT.

 

Also they have a suggested layout on the datasheet as well, which includes no ground plane around the chip and capacitors.

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When you connect tracks to pins of a package that is not using your grid measurements, you should start the track from the actual pin, that way it is centred exactly on the pin and you move out from there.  If you are going pin to pin, start from one pin, go half way, and then restart on the other pin and connect in the middle.

 

Usually you don't need a 5v level shifter for I2C.  Since it uses pullups and just sinks current you can use 3.3V pullups and it will work with 5V devices.

Well, not really. At 3.6v it works, 3.3v is a bit beyond the standard Vcc * 0.7 for VoH that is standard. At 5v, a device will, on average, only register a logic high at 3.5v or above. Below that, it might, it might not. i2c has plently of logic shifters because of that.

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Thanks for all the suggestions guys.  I fixed the vias...I thought Eagle added them automatically when you jumped layers and not just told you where to place them.  I also cleaned up the routing some and I think I fixed the random connection issues....although on my screen, I didn't see many missed connections.

 

 

When you connect tracks to pins of a package that is not using your grid measurements, you should start the track from the actual pin, that way it is centred exactly on the pin and you move out from there.  If you are going pin to pin, start from one pin, go half way, and then restart on the other pin and connect in the middle.

 

Can you expand on this?  I've been trying to get this to work with zero success.  It keeps snapping to the grid and not on the pin.

 

Good to know about I2C working with 3V pullups.  I'm also making this for a 5V bluetooth UART adaptor which would need translation at least in one direction.  I should probably change the buses to read A and B instead of SCL and SDA.

 

I thought about using all SMTs...it would certainly let me shrink the board and make it cheaper.  I just don't have a collection of smt resistors and caps on hand, so I would spend more on extra parts than I would save by shrinking the board...unless you guys know of a cheap place to buy low quantity parts.

 

 Do the data lines on SPI work the same as I2C?  I'm trying to think of the best way to extend SPI to this to make it more universal.

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Can you expand on this?  I've been trying to get this to work with zero success.  It keeps snapping to the grid and not on the pin.

 

Good to know about I2C working with 3V pullups.  I'm also making this for a 5V bluetooth UART adaptor which would need translation at least in one direction.  I should probably change the buses to read A and B instead of SCL and SDA.

 

I thought about using all SMTs...it would certainly let me shrink the board and make it cheaper.  I just don't have a collection of smt resistors and caps on hand, so I would spend more on extra parts than I would save by shrinking the board...unless you guys know of a cheap place to buy low quantity parts.

 

 Do the data lines on SPI work the same as I2C?  I'm trying to think of the best way to extend SPI to this to make it more universal.

 

When a net is unrouted between two points, just click on the point closest to the pin on the chip with the route tool and your routing will start from there.  If you find the trace is moving to the side rather than straight out from the pin, then right click the mouse to change the routing method.

 

It's worked for me with 3.3V pullups, but I have not used it often.  ED up there pointed out that 3.3V is outside the spec though, so it is not guaranteed to work so a level shifter would be useful.

 

The SMD were not for shrinking the board, they are recommended by the spec to shorten the path to the caps.  Unfortunately you don't have your location listed so the stores I post might not work for you.  You can buy SMD caps and resistors from Digikey/Mouser for cheap in tens or hundreds.  It's just the shipping that will be annoying if you are doing such a small order.  If you can wait, then ebay and dx.com both have selections of SMD caps/resistors.  It takes a few weeks to get them here, though.

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Jeremy Boyd has a very good 2 part series on YouTube dealing with routing and using the net tool over the wire tool. I purchased a MezzoMill to do prototyping on (arrived broken by the courier, so that plan went south) and have been practising using those techniques. We have a local fabrication place (PCBZone) that is set up to help out small board runs so I'll try that out, but you guys are really amazing with your level of help!

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Okay...

 

Try 2.  This time with smd caps with layout following data sheet.  I left the resistors as through hole to reduce the number of vias.  This board checks out in DRC except it complains about the restrict layer I used to kill the ground plane around the IC's, as I actually have components in it.

 

One question....how do I edit the silk screen for the components?  Do I need to edit it in the library itself or can I modify it just for this board?

shifter_SMD.brd

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One question....how do I edit the silk screen for the components?  Do I need to edit it in the library itself or can I modify it just for this board?

 

You can modify library if you only need to change one out of dozens of components (but do create your own library when doing that, will make upgrading to newer version a lot easier and you will not loose your changes.)

If you want to change all or almost all components, add your text in a new layer, then processing job, disable all text layers and enable your new layer

 

However, some parts will have text in Place or other layer. In that case your only option is to edit the library.

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