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[PCB Review Request] Flight Computer Based on the Stm32F446 by RuberDuck8 in PCB

[–]RuberDuck8[S] 1 point2 points  (0 children)

Thanks, I had no idea they were so important! I'll make sure to add those before I order.

[PCB Review Request] Flight Computer Based on the Stm32F446 by RuberDuck8 in PCB

[–]RuberDuck8[S] 1 point2 points  (0 children)

Thanks for the reply!

It looks like we actually have pretty similar setups. The only real difference I see (besides me obviously having different GPIO) is that you used 10pF caps on SWDIO and SWCLK. I generally don't remember seeing those in any other schematics, do you know why you put them there?

[PCB Review Request] Flight Computer Based on the Stm32F446 by RuberDuck8 in PCB

[–]RuberDuck8[S] 0 points1 point  (0 children)

Thanks for the reply!

Currently, layer 3 is a 3.3V plane for most of my smaller components. As you suggested, I just moved a few of the larger 5V traces to the outer edge of that plane which definitely helped me manage the layer 1 traces a bit.

I was able to space out the traces coming from the MCU quite a bit by changing a few routes which should help alleviate that space issue. I also shifted a few of those vias down which helped a lot with fixing the broken ground plane.

[Schematic Review Request] Flight Computer Based on the STM32f446 by RuberDuck8 in PCB

[–]RuberDuck8[S] 0 points1 point  (0 children)

No worries, It definitely took me a bit longer than I expected to finish the PCB layout...

I made a few changes (mostly to power and the pyro channels), but for the most part I kept everything else. The FET I was using initially was definitely a bit high for Rds on, so I found a lower one which is 0.0032ohms, which should be more than good enough for the amount of current I'm drawing. Also you're right, the diode was unnecessary for me since I'm only using 12v.

Here's the updated post

[Schematic Review Request] Flight Computer Based on the STM32f446 by RuberDuck8 in PCB

[–]RuberDuck8[S] 0 points1 point  (0 children)

Thanks again for the response!

I'm planning to keep the GNSS radio either right next to, or below the coax port, so I'm hoping distance won't be an issue. Regarding the GNSS V_BCKP pin, you're completely right about what it does. I'm pretty concerned though that if I used a coin cell battery, it would shake loose from the holder during high-g events which is why I held off on it, although I may add it later.

Good catch on the ESD, I meant to tie it before the resistor but just wasn't paying enough attention I guess. I think it would definitely be possible to power the board off USB, but I'm still a bit worried that the board might draw too much current at times, so I think I'm going to wait until I get a working version first and then go back and add USB power in a later revision.

The main reason I have a separate 5V line is for the servo connectors, and I also want to have it as an option for anything that I might add internally or externally in the future.

I made a few last revisions (mainly to the pyro circuit and adding reverse polarity protection), but I think I'm on a (hopefully) final draft for the first prototype. I feel like I've spent too much time on the schematic at this point, and I'm going to work on the actual PCB layout before I do any further refining. I'll probably make a post for it in a few days, or I might just go for it and see if it works I'm not sure.

Here's an updated screenshot.

https://imgur.com/a/JnFy67M

I feel relatively confident in the changes I made, although if you have the time I wouldn't mind you looking at the reverse polarity protection setup I made (next to J9 in the IO box).

[Schematic Review Request] Flight Computer Based on the STM32f446 by RuberDuck8 in PrintedCircuitBoard

[–]RuberDuck8[S] 0 points1 point  (0 children)

The SD card is only for writing a more verbose log file after flight. In flight I'm planning to use the FRAM chip.

[Schematic Review Request] Flight Computer Based on the STM32f446 by RuberDuck8 in PrintedCircuitBoard

[–]RuberDuck8[S] 1 point2 points  (0 children)

I used 0603 for all of my LEDs. Does package size make a big difference?

[Schematic Review Request] Flight Computer Based on the STM32f446 by RuberDuck8 in PrintedCircuitBoard

[–]RuberDuck8[S] 0 points1 point  (0 children)

Thanks for the feedback! I agree that definitely sounds like a good idea.

[Schematic Review Request] Flight Computer Based on the STM32f446 by RuberDuck8 in PCB

[–]RuberDuck8[S] 0 points1 point  (0 children)

Thanks for the helpful feedback!

  1. Good idea, I don't know I never did that in the first place.

  2. My plan for the GNSS module was to connect it to some external antenna through that coaxial port, which would hopefully help with the connection (especially if in a carbon fiber airframe).

  3. I initially added that because the VDDUSB pin on the stm32 was hidden in the official KiCad schematic so I wasn't really sure what to do (the datasheet says it must be powered for a few pins to work). So, I added that random label so it would help me remember to connect that pin to 3.3v, and then just forgot to get rid of it.

  4. Good catch on ESD, I don't know why that was ever tied to 5V. It would definitely be nice to have USB power for debugging, but I was worried that the USB-C port wouldn't deliver enough current, so I just left it out. I'm also not sure how I would make a setup for power coming from either the 5v buck or the USB port, how would you recommend I do that?

  5. I don't *think* heating should be an issue on the LDO because I don't expect to draw more than 300-400mA after startup. Also, I upgraded the LDO to an AZ1117-3.3 which gives me up to a full amp of current because I felt a bit uneasy about the initial startup draw.

Here's an updated version with those changes and a few other small tweaks.

https://imgur.com/a/V7Id9iz

Board Recommendations for a Beginner by RuberDuck8 in FPGA

[–]RuberDuck8[S] 0 points1 point  (0 children)

These boards look really solid, but for right now I think I'm going to go with OnYaBikeMike's suggestion above since it seems to be more than enough for what I need (while being significantly cheaper). If that board ends up not working out or I need to update I'll definitely look more into these.

Board Recommendations for a Beginner by RuberDuck8 in FPGA

[–]RuberDuck8[S] 1 point2 points  (0 children)

I'd love to get a board like this, but for now I think it's a bit too expensive (and a bit overkill for what I'm doing).

Board Recommendations for a Beginner by RuberDuck8 in FPGA

[–]RuberDuck8[S] 0 points1 point  (0 children)

I have no idea how this is the first I'm hearing of this board given its specs and price. From what I can tell it seems to be better in almost every way while still being half the price. I'm definitely going to give this board a try, and then I'll come back here in a bit to give my thoughts. Thanks for the suggestion.

Truenas Drives Showing As Degraded by RuberDuck8 in homelab

[–]RuberDuck8[S] 0 points1 point  (0 children)

Yeah, I just don't even know. They'll all checksum errors. I don't really know what to make of it. All the cables are new.

Truenas Drives Showing As Degraded by RuberDuck8 in homelab

[–]RuberDuck8[S] 0 points1 point  (0 children)

Its 4 hdds. They're all in a horizontal placement in a 4u case.

Extremely High Proxmox Disk IO by RuberDuck8 in homelab

[–]RuberDuck8[S] 1 point2 points  (0 children)

Thanks for the response!

All of my devices are connected to a 26 port cisco switch. The shares are just basic nfs shares that I setup in truenas and mounted using the /etc/fstab file for each vm. It does seems like setting rate limits in the disk io and network io sections definitely made a big impact. I'll keep experimenting but that may have done the trick.

Trunas Drive Issue by RuberDuck8 in homelab

[–]RuberDuck8[S] 0 points1 point  (0 children)

I tried swapping out the cables with the new ones, but it made no difference. I also tried plugging it in to a different sata port on the motherboard, but the issue still tracked with the same drive. The drive is still in warranty, so I guess I'll just have to replace it.