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Please review first PCB attempt

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I have a BMP085 pressure sensor, an analog humidity sensor (HIH-5031-001), and a digital ds1820 temp sensor working on a breadboard.


I am trying to create a booster pack with a 6 pin header for the pressure sensor, two 3 pin headers for the humidity and digital sensors, and a 2 pin header for serial out along with two 10k pullup resistors for the pressure sensor.


Attached is my first attempt at Eagle.


Am I on the right track?


I appreciate any and all comments!







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while you placed the components on the board you didn't draw in any of the traces,  the yellow lines you see are the "rats nest" that show you what connects to what, you need to use the "route" command to connect up the things.


You will also need to place a "ground plane" on the top and bottom layers of the board (red and blue)  by drawing a polygon and naming it your ground signal name (GND) probably.


Since you are setting your "dimension" boundary using a part, you don't need to draw it in manually.


you can use auto route to give you a place to start from, set the grid to 20 ish, then let it run.  now you can go in and clean up and play with it rather than having to do it all yourself


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Not much that can go wrong here.  I did not check the pin assignements.  You have two pins on the 6 pin header unconnected.


I'm not certain about these headers.  Are these headers going out to breakout boards that are already made for these chips?


The only thing I see is that this board is a little too simple to even need to be made.  The only thing you have on it other than headers is two pullups.  If you are making this just as a test, that's fine, but it seems to me you can freehand wire this easier than making up a PCB in this case.


EDIT:  You've made your breakout board the size of the entire launchpad.  You probably want the dimension of your board to be much smaller.

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yes, this will be very expensive to fab for not much more functionality than a ribbon cable.  Do you have a specific use for this board, or is it just for fun?


I would personally work your pinout until you can shrink the board down to a much smaller size to make it cheaper.  I would also mount the sensors directly to the board instead of using breakouts.   Another thing to consider is add more functionality.  Maybe add some LED's or some seven segment displays to indicate the values of the sensors...maybe use a push button to cycle which sensor is displayed.  You could also add an RS232 transceiver to it, which would make running it as a stand alone remote sensor much simpler.


Another thing you might consider doing is abandoning the booster pack idea and build the micro and all of the sensors into the board itself, so you have a single, flash drive sized (or smaller) board.  It really is not much more difficult to do...you can even use the launchpad schematic as a guide.

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Sorry for the slow response, real life got in the way...


This is just for fun to get to know the tools.  I took a few EE classes in college 10 years ago and wanted to learn/re-learn some practical electronics.


The board was simple by design.  Wanted to start out slow and make sure I understood all the steps and increase the complexity incrementally.  Even the simplest projects seem to be harder than I expected.  Like getting the BMP085 to work.  How hard could it be to get i2c to work?  It was much more of a challenge than I expected.


I think I'll add another set of headers to connect an LCD and work on getting that working later.


Next project will be to put the micro and all components on their own board.  What additional components are absolutely required to put an MSP430 on a board?  Voltage regulator and what else... I am trying to make that transition from bread-boarding stuff with the launchpad to full blown integrated circuits.


Also, any rules of thumb about the size and location of ground planes?


Thanks for the great info!

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Yep, it is really easy to get an MSP430 running stand alone.  Just make sure the test and reset pins are connected with the proper passives (use the launchpad schematics as a guide) and you are all set.  You typically won't have to worry about ground planes and special routing unless you are dealing with high power or large thermal loads (e.g. h-bridge chips) or high speed signals.


Everything else on the board will depend on what else you plan on attaching to the board.  Figure out how you plan on powering and communicating with the board, and that will tell you what else you need.

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