How to Make a Good PCB - Design Problem

[Zoe313]

Good day, all
This is my first attempt at doing this. I want to try my hand at creating a consolidate PCB. Also I am using Eagle for this, again a first time user.
My Goal: a single compact PCB with the Atmega32u4 & BNO080 connected together via I2C, an ICSP header for programming the 32u4, a buzzer as the output, and two 2032 coin cells to drive it. This will be a 3.3V board.

Would someone be willing to review my schematic for errors/omissions?

 

[MacIntoshCZ]

difficult to read

 

[Diver300]

I agree with MacIntoshCZ. Please post a clear image.

Do you want an On-Off switch?

I would suggest that you should be able to run from a single CR2032. The BNO080/BNO085 will work from 1.7 to 3.6 V, and the ATmega32U4 will work down to 2.7 V.

A CR2032 is about 80% depleted at 2.7 V, so you will have to throw away the battery having used 80% of its capacity.

If you put two CR2032s in series, you will be able to use them to the point where they are completely flat. However you are using two, not one, and taking the same current from each that you would take from one, so the half of the energy in the batteries will have ended up just heating the voltage regulator.

Just put two in parallel, or use a larger cell, like a CR2450, and don't bother with the regulator.

 

[MaxHeadRoom78]

Why the N.C X's on the 3V3 and the GND? , I don't use Eagle, but the program I do use uses a Power Flag to denote this.

 

[Pommie]

If space is at a premium then consider making everything (except battery holder) surface mount. If you go to easyEDA then you can design your board using their free software and get a quote to have 5 made from JLC PCB with all the surface mount components soldered onto the board. They don't have the BNO085 but do have the BNO055 which might suffice. There are a few threads here about using the service.

Mike.

 

[Pommie]

For compact size and a nice capacity, I like the sparkfun rechargeable batteries. That'll give about 50 hours of use if you can fit it.

Mike.