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[Reply #15 on:]

reset and GND for external reset button. And the 2 standalone pins below the mini is the +5/GND pin header for the bluetooth module.

Ok, so that reset doesn't actually have live voltage on it, those two pins are just bridged, nothing else, right?

Yes it's to be a stacked shield. It's going to get power via wire jumpers from the logic board's 3V3 and ground. I have pass-through headers on the logic level for this reason.

If it's going to get stacked on top of the larger one, why use wire jumpers?  Why not pass voltage and ground through the headers?  Avoid the whole wire jumper mess all together.

You could take advantage of ground planes also, will give you more room for your thicker traces.

That's exactly what I'm going to do with the ground plane.  Gets rid of all the ground traces, leaving more room for the rest.

[Reply #16 on:]

If using Eagle, draw a polygon on both sides of the board, and name each one GND.
All you GND pins will connect to this, you will not need to drawa them out.
Gives you more flexibity for routing signals.

Example: You can see the traces, seperated by thin white trace, in the middle of the sea of red, which is the top layer ground plane.
Bottom looks similar, but in Blue (default colors). Pins the + across them are connected to ground.

[edit - I typed this up, submitted, then saw there was a page 2, so it looks out of order  ]

[Reply #17 on:]

He's not using Eagle ... he's lost in it.   I'm helping with converting his cad design into Eagle so he can get the gerber files for his fab house.

[Reply #18 on:]

This discussion just went over my head :blush:

Arduino Mini doesn't have 3V3 onboard to feed the shield. Have to get it from elsewheres. No easy way to get ground from..anywhere..to the IC, so have to get it from elsewheres as well. Thus 2 power wires going to nearest tappable 3V3 and GND (the logic level).

[Reply #19 on:]

Maybe these will help clear things up:

Arduino Mini V4: http://arduino.cc/en/Main/ArduinoBoardMini

LCD connection: http://ladyada.net/products/nokia5110/

74HC4050: http://www.mouser.com/ProductDetail/NXP-Semiconductors/74HC4050N652/?qs=sGAEpiMZZMutXGli8Ay4kE3wRMDwmh%2f%252bwxAjZ9wobYY%3d

RST (reset) pin of the LCD (orange wire) to pin 2 of the 4050
CS (chip select) pin (yellow wire) to pin 4 of the 4050.
D/C (data/command) pin (green wire) to pin 6 of the 4050
DIN (data in) pin (blue wire) to pin 15 of the 4050
CLK(clock) pin (purple wire) to pin 12 of the 4050.

Arduino pin 3 (orange) goes to pin 3 of the 4050.
Arduino pin 4 (yellow) goes to pin 5 of the 4050.
Arduino pin 5 (green) goes to pin 7 of the 4050.
Arduino pin 6 (blue) goes to pin 14 of the 4050.
Arduino pin 7 (violet) goes to pin 11 of the 4050.

Let me know if it's too hard to read these.

[Reply #20 on:]

This discussion just went over my head :blush:

Arduino Mini doesn't have 3V3 onboard to feed the shield. Have to get it from elsewheres. No easy way to get ground from..anywhere..to the IC, so have to get it from elsewheres as well. Thus 2 power wires going to nearest tappable 3V3 and GND (the logic level).

No, see this is where a ground plane comes into play.  Then it doesn't matter where you grab it from, ground is ground and will remain ground.

Ok, let me see if I can figure this out.  You are putting a mini onto the large board.  Then, you are stacking the smaller board on top of that?

[Reply #21 on:]

This discussion just went over my head :blush:

Arduino Mini doesn't have 3V3 onboard to feed the shield. Have to get it from elsewheres. No easy way to get ground from..anywhere..to the IC, so have to get it from elsewheres as well. Thus 2 power wires going to nearest tappable 3V3 and GND (the logic level).

No, see this is where a ground plane comes into play.  Then it doesn't matter where you grab it from, ground is ground and will remain ground.

Ok, let me see if I can figure this out.  You are putting a mini onto the large board.  Then, you are stacking the smaller board on top of that?

doesn't solve the 3V3 problem....and yes. The Arduino Mini, Logic Leveler, power regulators, sensors, breakout pin headers, all go on the big board.

The small board is a shield for the Arduino Mini that holds a 74HC4050 (I just editted my post with that info) that controls the LCD display that's on the other end of a DB9 connector.

Does the ground plane not count as a layer? (Limited to 2 layer PCB, Laen doesn't have enough 4 layers to make an order yet).

[Reply #22 on:]

No, the ground planes do not count as layers. Ground just becomes everything that is not a signal.

Can you see it here? The pins that have + across them are the pins that are grounded. The thin strips that are separated with the white outlines are signals, the thick one are power. The yellow octagons are vias that connect the top layer to the bottom.

You can also see some areas that are isolated and not connected to a pad, or hole, or a via. 
If these were large areas, I would try to add a via to to connect it to the ground layer on the other side.

[Reply #23 on:]

Ok, I see what you mean about the 3V3 for the stackable board.  Is the attached picture of a mini the same as yours?  You need to tie those ground pins together (which a ground plane will easily handle, no need for traces all over the place.)

The single trace going to pin 5, is there a reason why you just have a single pin there, as opposed to two pins like everywhere else?

Also, you know your stacked board doesn't match the headers (by one row), right?  The headers are 0.1" wider ...

This would honestly be so much easier if you had an electrical diagram drawn out.  Not a board.

(forgot the board)

[Reply #24 on:]

Ok, I see what you mean about the 3V3 for the stackable board.  Is the attached picture of a mini the same as yours?  You need to tie those ground pins together (which a ground plane will easily handle, no need for traces all over the place.)

Yes, and I currently don't have the grounds tied....

The single trace going to pin 5, is there a reason why you just have a single pin there, as opposed to two pins like everywhere else?

breakout pin is optional for pin 5 since it's reserved for the frequency counter library

Also, you know your stacked board doesn't match the headers (by one row), right?  The headers are 0.1" wider ...

well shoot, I missed that. And I don't really know how to fix it, either...I can't flip the IC because that makes all the data lines cross in an ugly fashion...

Idea- bring the right side in 1 column, and sacrifice the +5V and A1 pins. I can clip off the wires after the solder joint, so they don't go into the headers on the Mini. I don't use them on this project anyways. And they're still broken out on the main PCB.

(ignore the dark green over light green- I can't draw the angles like you can to make them go around eachother)

[Reply #25 on:]

Yes, and I currently don't have the grounds tied....

Easily fixed with a ground plane.

breakout pin is optional for pin 5 since it's reserved for the frequency counter library

It's easier to simply plop a 2x12 header, as opposed to three separate ones, two of 2x and a single pin.

well shoot, I missed that. And I don't really know how to fix it, either...I can't flip the IC because that makes all the data lines cross in an ugly fashion...

Idea- bring the right side in 1 column, and sacrifice the +5V and A1 pins.

This is where having the actual electrical schematic comes into play.  Because you have the ability to run wires both top and bottom layers (and *through* the layers), it's easily fixed.  However, without seeing the schematic, without knowing what your constraints are (like, do the two boards need to be that size?), it's hard to make a proper design.

I'm assuming because you have headers, your sensors are on breakout boards, yes?

[Reply #26 on:]

see image added above. Fixes the alignment issue.

Sounds like ground plane will fix the common groundings.

Trying to keep footprints small, I'm already $200 over budget on this (eek). Right now this is @ 6 square inches = $30.

Yes, sensors are on boards.

[Reply #27 on:]

It can be made much smaller, can probably even be one single board instead of two stacked.

Tell you what, tell me what the regulators are that you're using (specifically).

You have an Arduino Mini (rev. 4)
You have an 74HC4050 IC Shifter
You have a logic level converter - do you have a link to this?

You need breakouts for:
DS1307 RTC (5 pins I²C)
HH10D Humidity Sensor (5 pin I²C)
BMP085 (6 pin I²C)

Are these all SparkFun breakout boards?  If not, can you give me direct links to them from whatever vendor you got them from, so I can make sure i have the correct foot print?

It will be fed from a 9V battery going into the two regulators which regulate down to 3V3 and 5V respectively.

Did I forget anything?  Oh yeah, does the board need to be that specific size?  What if it can be made smaller?  What about specific shape?  There are cheaper options to making a board by the way.  Just takes time.

[Reply #28 on:]

Arduino Mini (rev. 4)
74HC4050 IC Shifter (NOTE: cannot use connections as given on linked page. See below)
logic leveler -> http://www.sparkfun.com/products/8745 (using Tx pins)

DS1307 RTC (5 pins I2C) -> http://www.sparkfun.com/products/99
HH10D Humidity Sensor (5 pin I2C) -> http://www.sparkfun.com/products/10239 (Freq MUST go to pin 5. This disrupts the 4050, see below)
BMP085 (6 pin I2C) -> http://www.sparkfun.com/products/9694

BlueSmirf RP-SMA -> http://www.sparkfun.com/products/158 (is case mounted, connects via wires to pin headers)

3.3VDC Regulator: http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00000544.pdf

5.0VDC Regulator: http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00000443.pdf

The 4050 is set up to use pins 3, 4, 5, 6, 7. Due to the HH10D, this cannot happen. I am using 2, 3, 7, 8, and 9 instead.


The LCD is on the other end of a 16 ft DB9 cable. So the respective pins just need to be headerized.

RST (reset) pin of the LCD (orange wire) to pin 2 of the 4050
CS (chip select) pin (yellow wire) to pin 4 of the 4050.
D/C (data/command) pin (green wire) to pin 6 of the 4050
DIN (data in) pin (blue wire) to pin 15 of the 4050
CLK(clock) pin (purple wire) to pin 12 of the 4050.

Arduino pin 2 goes to pin 3 of the 4050.
Arduino pin 3 goes to pin 5 of the 4050.
Arduino pin 5 goes to pin 3 of the HH10D.
Arduino pin 7 goes to pin 7 of the 4050.
Arduino pin 8 goes to pin 14 of the 4050.
Arduino pin 9 goes to pin 11 of the 4050.
Arduino pin A4 goes to pin 1 of the logic level board
Arduino pin A5 goes to pin 6 of the logic level board
Sensors SCL go to pin 7 of the logic board (check me)
Sensors SDA go to pin 12 of the logic board (check me)
Rx of Bluesmirf goes to Tx of Arduino
Tx of Bluesmirf goes to Rx of Arduino

BMP085, HH10D, 4050, and LCD are 3.3VDC
DS1307, Arduino, Bluesmirf are 5.0VDC

The idea, is that everything is socketized for easy swap-out in event of <insert anything that can happen to an electric circuit here> without using a soldering iron.

The HH10D and BMP085 I both have set up so they hang over the edge of the PCB.

The DS1307 stands up on end using right angle headers.

The enclosure is 4" x 6". The battery is the full 6" long. So there is plenty of room in the box, just trying to stay small for $$ reasons.

[Reply #29 on:]

Ok, let me mull over this tomorrow and play with it.  As for the cost of the board, how quickly do you want it done?  If you don't mind waiting, you can get ten (10) 50mm x 50mm boards for $9.90 + s/h.  It just takes upwards of two weeks to get.

Personally, I prefer not to have breakout boards hanging off of the edges, I'd rather place them over an open area on the main board for support.  But we'll see what I can come up with.  The majority of the space will be taken up by the Mini as it is.

Another question, you want everything to be through hole, right (since you mentioned you already have it working on breadboard, I'm assuming you're just going to transfer from one to the other)?