Custom Flight Controller Board design - Suggestions and Criticisms

Thread Starter

TommasoB

Joined Nov 26, 2023
27
Hello community,

My name is Tommaso Bugliesi and I am currently designing a custom flight controller board.

It's not just one board, but rather two boards to be stacked on top of each other using rubber dampers. The hole spacing is 30.5mm, and the overall dimensions of the two boards is 34mmx34mm.

The project is based on the ESP32-WROOM-UE, while the chosen sensors include a Bosch BMI323 IMU, a Bosch BMP280 barometer, an LIS3MDLTR magnetometer, and a u-blox NEO-6M GPS.

The first board includes the ESP32, a voltage regulator, and the CP2102N chip. The second board incorporates the sensors and interface pins with the ESCs of the brushless motors.
The two boards communicate with each other through a 32-pin ribbon cable.

As the first board I soldered was not working, I am looking for criticism about the electric schematic that may prevent the boards to work correctly and suggestion related to the PCB layout, as I am new to this field.

Thank you in advance for your help!

Kind regards,
Tommaso
 

Attachments

LowQCab

Joined Nov 6, 2012
3,957
Purchase a Commercially available Flight-Controller.

You can't make one yourself that has any advantage over the commercially available ones,
and, they are relatively cheap, and they come with a warranty.

The success of your project depends completely on
it's total compatibility with existing, standardized, Firmware.
.
.
.
 

Thread Starter

TommasoB

Joined Nov 26, 2023
27
Purchase a Commercially available Flight-Controller.

You can't make one yourself that has any advantage over the commercially available ones,
and, they are relatively cheap, and they come with a warranty.

The success of your project depends completely on
it's total compatibility with existing, standardized, Firmware.
.
.
.
Thank for your reply LowQCab.

Actually, the goal of this project is to get into PCB design and learn how to work with micro-controllers.
I expect to develop my own firmware and controls logic putting into practice what I have learnt in 5 years of university.
 

LowQCab

Joined Nov 6, 2012
3,957
In that case ...........
I would purchase some popular Commercial offerings just to see
how, and why, they did it the way that they did.

Or,
many manufacturers provide general Schematics that may be enlightening.
.
.
.
Holybro Kakute F7 V1.5  c FLAT .PNG
.
Complete Wiring Schematic FLAT .png
.
 

Attachments

Thread Starter

TommasoB

Joined Nov 26, 2023
27
In that case ...........
I would purchase some popular Commercial offerings just to see
how, and why, they did it the way that they did.

Or,
many manufacturers provide general Schematics that may be enlightening.
.
.
.
View attachment 308714
.
View attachment 308716
.
Please stick to the thread question: "I am looking for criticism about the electric schematic that may prevent the boards to work correctly and suggestion related to the PCB layout"

See attachments for schematics and boards layout.

I know how a flight controller works and mine integrates all the components you mentioned in your reply. Gps is integrated in the board as well as receiver/transmitter (I expect to use ESP NOW protocol with a custom remote controller). PDB is the third board of the 3 boards stack and I already have it. Power input from PDB is done via the JST connector on the board. Board 1 integrates a voltage regulator to supply Board 2.
 

Ya’akov

Joined Jan 27, 2019
8,975
Hello community,

My name is Tommaso Bugliesi and I am currently designing a custom flight controller board.

It's not just one board, but rather two boards to be stacked on top of each other using rubber dampers. The hole spacing is 30.5mm, and the overall dimensions of the two boards is 34mmx34mm.

The project is based on the ESP32-WROOM-UE, while the chosen sensors include a Bosch BMI323 IMU, a Bosch BMP280 barometer, an LIS3MDLTR magnetometer, and a u-blox NEO-6M GPS.

The first board includes the ESP32, a voltage regulator, and the CP2102N chip. The second board incorporates the sensors and interface pins with the ESCs of the brushless motors.
The two boards communicate with each other through a 32-pin ribbon cable.

As the first board I soldered was not working, I am looking for criticism about the electric schematic that may prevent the boards to work correctly and suggestion related to the PCB layout, as I am new to this field.

Thank you in advance for your help!

Kind regards,
Tommaso
Hey, Tommaso.

I expected you to get more responses by now. Maybe if there is a bit more activity on the thread it will provoke people to look so I will give you my not-very-important feedback as I don’t have th expertise on PCB layout and your BoM seems basically unassailable.

Here’s my take:

I know that 2.54mm pin headers are “industry standard” for this application, but they shouldn’t be. They are easy to bend, much higher profile today than when they were settled on (everything has gotten a lot smaller) and lack keying so are easily to install backwards or offset.

Though it would mean at least putting adapters on the external components (they would be pigtails going from pin header to new connector, and covered with heat shrink to make unplugging them improbable), or replacing the pin header connector with the new one, it would reduce the board’s footprint and make the connections more reliable and less prone to human error.

I know that’s not very helpful, but there you go. I hope this helps attract more opinions for you.
 

Papabravo

Joined Feb 24, 2006
21,029
When you ask for free help, you need to accept whatever comes your way. Admonishing people to " Please stick to the thread question " will most likely deter them from even looking at the problem. If we fail to meet your expectations it will be on to the next option for you.
 

sghioto

Joined Dec 31, 2017
5,369
As the first board I soldered was not working, I am looking for criticism about the electric schematic that may prevent the boards to work correctly and suggestion related to the PCB layout, as I am new to this field.
Were the circuits ever tested on a breadboard to verify operation either separately or combined?
 

Thread Starter

TommasoB

Joined Nov 26, 2023
27
Hey, Tommaso.

I expected you to get more responses by now. Maybe if there is a bit more activity on the thread it will provoke people to look so I will give you my not-very-important feedback as I don’t have th expertise on PCB layout and your BoM seems basically unassailable.

Here’s my take:

I know that 2.54mm pin headers are “industry standard” for this application, but they shouldn’t be. They are easy to bend, much higher profile today than when they were settled on (everything has gotten a lot smaller) and lack keying so are easily to install backwards or offset.

Though it would mean at least putting adapters on the external components (they would be pigtails going from pin header to new connector, and covered with heat shrink to make unplugging them improbable), or replacing the pin header connector with the new one, it would reduce the board’s footprint and make the connections more reliable and less prone to human error.

I know that’s not very helpful, but there you go. I hope this helps attract more opinions for you.
Thank you for supporting the post and for your feedback. I agree that 2.54mm pin header are today clumsy if compared to other connectors and I may consider to change them in the next version of the PCB. For this version I opted for them, to avoid modifying the ESC connectors which are all based on that 2.54mm pin header, but this is actually a good point :)

I apologize if my previous answer sounded harsh, my only thought was not to deviate from the original purpose of the thread.
 

Thread Starter

TommasoB

Joined Nov 26, 2023
27
Were the circuits ever tested on a breadboard to verify operation either separately or combined?
The problem I faced was related to the CP2102 module, I was not able to connect the board to the computer. For this issue I opened a dedicated post ESP32 based Custom Flight Controller - Drones
The Board 1 you see in this post is the second design version, the first one had a different layout but the same electric schematic.

In order to test the functionalities of the GPIO I also designed an expansion board that can be connected to a breadboard. Unfortunately I could not test it.
 

Thread Starter

TommasoB

Joined Nov 26, 2023
27
Hi T,
I'm also intereted in this type of thing, and am learning as I go, but I'm much older so not as mentally agile, as I imagine you are.
I'll suggest my thread for some ideas, and you may learn something, or at least learn what not to do :)
https://forum.allaboutcircuits.com/threads/remote-control-by-location-pic-in-oshonsoft.148795/

I'll try to check your PCBs if i can.
Cheers, C.
I started reading your post and it seems there is a lot to learn from that. Currently, I don't have much time to read the all 65 pages of the thread, but I would be happy to help you with the code if you need.

You find attached the kicad_sch and the kicad_pcb of the first board in the zip file as requested. It's nothing particularly special, just and esp32-wroom-UE with connectors and a USB to UART chip.
 

Attachments

camerart

Joined Feb 25, 2013
3,652
I started reading your post and it seems there is a lot to learn from that. Currently, I don't have much time to read the all 65 pages of the thread, but I would be happy to help you with the code if you need.

You find attached the kicad_sch and the kicad_pcb of the first board in the zip file as requested. It's nothing particularly special, just and esp32-wroom-UE with connectors and a USB to UART chip.
Hi T,
Hopefully you will overtake my skills, with your more computer literate and agile brain, which is why my posts are so long.
Perhaps it's best if you ask me questions, and I can I can point to to the similar question and answer I had in the thread.

I'll see if I can find anything in board 1 that may cause a problem, but I'm far fro being an expert.
I'll let you know whether or not I find anything.
C
 
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camerart

Joined Feb 25, 2013
3,652
The problem I faced was related to the CP2102 module, I was not able to connect the board to the computer. For this issue I opened a dedicated post ESP32 based Custom Flight Controller - Drones
The Board 1 you see in this post is the second design version, the first one had a different layout but the same electric schematic.

In order to test the functionalities of the GPIO I also designed an expansion board that can be connected to a breadboard. Unfortunately I could not test it.
Hi T,
I haven't been able to open your SCH and PCB into Kicad yet, perhaps you have to send me the whole PRO?
C
 

Thread Starter

TommasoB

Joined Nov 26, 2023
27
Hi T,
I still can't open it properly, will you try again, but post all of the files within the PRO please?
PRO, PCB, NET, SCH, cache.lib, rescue.lib in fact all of those files.
C
Before uploading the zip I tested that it was working. I am using a kicad v7 and I sent you all the files needed.
 

camerart

Joined Feb 25, 2013
3,652
Before uploading the zip I tested that it was working. I am using a kicad v7 and I sent you all the files needed.
Hi T,
Ok, I also have V7, are you sure it wasn't associating with the files I mentioned?
I'll try again
EDIT: It's now working
C
 
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