Aaron,

This is an epic little project. I'd love to help out. I won't be able to
make the design review on Tuesday. However, I glanced over your schematic
and wanted to point out a few things I saw.

1. Since you aren't using the AC adapter on it, get rid of that LiPO
Charger. You are paying like an extra dollar just for that. Here's a
Cheaper LiPO charger: http://www.digikey.com/product-search/en?keywords=
MCP73871-2CCI%2FML-ND
2. Apparently there is a version of your IMU chip that is like 3 bucks
cheaper? http://www.digikey.com/product-detail/en/
stmicroelectronics/LSM9DS1TR/497-14946-1-ND/4988079. And if you can't use
that one, maybe consider this bosch part (cheaper, got 4 less pins so
potentially smaller/less headache): http://www.digikey.
com/product-detail/en/bosch-sensortec/BMX055/828-1060-1-ND/6136311.
3. That xtal is stupid large compared to a surface mount equivalent. It
will be a little more expensive (like 60 cents a piece) but maybe the space
is worth it? I'd use something like this: http://www.digikey.com/
product-detail/en/abracon-llc/ABM3-8.000MHZ-D2Y-T/535-10630-1-ND/2344632
4. If you are really hurting for space, you can switch to smaller pin
headers. Personally, I like the .1 in pin headers because I've got tons of
jumpers for them so I wouldn't make the switch but its food for thought.
5. Literally all your parts need an attribute with a part number for the
manufacturer and distributor/vendor (digi-key in this case). This makes it
much easier to generate the BOM, trust me.
6. I think you might be able to find a smaller and cheaper slide switch
then the one you are currently using. I didn't have time to dig around for
you but I'm sure if you search for a SPDT slide switch on digikey or mouser
that is rated for 500mA (usb spec) that you'll find something.
7. The LDO and Voltage comparator schematic symbols need to be redone.
8. You can save additional space by switching to 0402 surface mount parts
where possible. If you are worried about how difficult those might be to
solder, you shouldn't be. Stencils are cheap and can be purchased from
here: https://www.oshstencils.com/. You can print out the tcream, tplace,
tnames, and dimension layers at a 1.0 scale then tape the paper flat on
like a spare piece of wood or something and spray it with spray adhesive
(which I think we have somewhere? or can at least buy some of) then place
your parts on it. Lay the stencil on the PCB then use a spreader (comes
with stencil) to spread some solder paste over it, then pick the parts off
the paper, place, and bake! I'd be willing to show you if you like.

Not related to the board/schematic, but the firmware could use a facelift.
I'd love to help if that is ok? I can get started on it asap just let me
know.

Anyway, hope this all helps. Awesome job and let me know if there is
anything else I can help with!

->Will

On Sun, Dec 11, 2016 at 5:19 PM, Aaron Baker <bitmapve...@gmail.com> wrote:

> My practicum class has built an Arduino-based avionics board intended for
> use in the "Introduction to Rocket Science" class next term. The git repo
> is here <https://github.com/rusinek/ECE411_RocketAv>.
>
> We need to do a post-mortem on rev 1 to generate suggestions for a rev 2
> over winter break.
>
> The focus is on:
> -Reducing cost
> -Reducing board size
> -Ease of manufacturing
>
> If you'd like to help, the design review will be
>
> 6-7 PM, Tuesday December 13
>
> (before the regular meeting).
>
>
>
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