Could someone suggest a place where I could request people to look over my schematic/board design?

If this is the place, here it is: https://easyeda.com/be.mihai22/project-hawk


As I see people started looking at this, here's what my thing looks like: enter image description here enter image description here enter image description here

The three diagrams will form a circuit that will fly a quadcopter. It contains 3 ICs (accelerometer/barometer/magnetometer/gyro) for drone stability, one IC for detecting current/voltage.

What is more, it has an interface for raspberry pi zero which will generate + communicate a PPM signal (like a receiver) from 4G/Wifi.

I will also keep a list of things that you have suggested for change in this header:

1. Sourcing 12V directly into ATMEGA328P Many thanks to Ron Beyer

  • 1
    \$\begingroup\$ Not sure this is the place, but why are you running 12V directly into an ATMega328? \$\endgroup\$
    – Ron Beyer
    Commented Jan 21, 2020 at 13:54
  • 2
    \$\begingroup\$ Upload a screengrab or image here so we don't have to follow a link. It might help to explain what the circuit does and what your concerns are. \$\endgroup\$
    – Transistor
    Commented Jan 21, 2020 at 13:58
  • \$\begingroup\$ Try the EEVBlog forum: eevblog.com/forum Indeed feeding 12 V directly into an ATMega328 is a recipe for disaster. The ATMega will be destroyed on the spot! \$\endgroup\$ Commented Jan 21, 2020 at 13:58
  • \$\begingroup\$ Great spot. I have updated the question and I will keep a list of problems encountered and by whom. \$\endgroup\$
    – bem22
    Commented Jan 21, 2020 at 14:22
  • 1
    \$\begingroup\$ One of the ICSP pins must be connected to the reset pin directly, not through a capacitor \$\endgroup\$
    – Sim Son
    Commented Jan 21, 2020 at 15:48

1 Answer 1


I'll add it as an answer, since the comments are getting big...

  • You should not supply 12V to the ATMega328. 3V3 would be a better choice here so you don't have to use level-shifting on the I2C lines.
  • You are pulling up the reset to 12V, change this to 3V3 as well.
  • You have 2 different grounds defined. This can cause problems and you should probably decide to name them the same or connect them with a 0R resistor.
  • No reverse voltage protection on the voltage inputs
  • VDDA (analog reference voltage) should be filtered, you can use a ferrite bead for this
  • The LED's are using 10K resistors, which may be too high for the 3V3 voltage, they will probably be so dim you can't see them.
  • The Inhibit pin on the LDO should be connected directly to 5V.
  • The input capacitor on the LDO should be between 5V and ground, not Inhibit.
  • 10K pull-ups for the I2C lines are probably too big. You should be using something in the 2.2K-4.7K range.
  • If you run the ATMega and the current monitor chips on 3V3 instead of 5V, you can eliminate the I2C level-shifting.
  • The HMC5883L should have a 4.7uF polarized capacitor on the C1 line.
  • VDD on the HMC5883L should have a capacitor placed close to the power pins.

Also, check the availability of some of your parts. The CSTCE16M0V53 looks to be obsolete/End-of-life.

  • \$\begingroup\$ This is great feedback mate. \$\endgroup\$
    – bem22
    Commented Jan 22, 2020 at 7:24
  • \$\begingroup\$ I started implementing and I have some questions. a) Why polarized capacitor for C1? b) Can you confirm that my level shifter is 2N7002DW? ( I copied this part at my best knowledge). Also, how should I submit my result for more feedback? I think reposting this is not really advised on stackexchange. Again, thank you so much for all the feedback. It's invaluable. \$\endgroup\$
    – bem22
    Commented Jan 22, 2020 at 8:45
  • \$\begingroup\$ Also, what properties should the ferrite bead have and why filtering VDD is necessary? \$\endgroup\$
    – bem22
    Commented Jan 22, 2020 at 9:43
  • \$\begingroup\$ The polarized capacitor is required by the datasheet, the device may use it for some internal circuitry so it's best to use the kind/size it recommends. I honestly believe you should get rid of the level shifter and run everything at 3.3V. The ferrite bead is required for analog circuitry inside the chip to run correctly with a good reference. You will have a noisy voltage source (with motors) so you want to filter the analog side. You might want to ask on meta about how to repost. \$\endgroup\$
    – Ron Beyer
    Commented Jan 22, 2020 at 13:06
  • \$\begingroup\$ Eliminated the level shifter. Running everything on 3V3 now. It was a great idea. Also realized my current sensor was mislabeled. My intention was to use that with the raspi bus (so I will have a separate bus). Here it is. easyeda.com/be.mihai22/project-hawk \$\endgroup\$
    – bem22
    Commented Jan 22, 2020 at 13:14

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