r/PrintedCircuitBoard

I've just completed the schematic for a custom STM32F405RGTx-based quadcopter flight controller in KiCad. This is my first full FC design and I'd love to get some feedback before moving to PCB layout.

**Overview:**

A full-featured flight controller targeting Betaflight compatibility, designed for 4S–6S LiPo (7.4–25.2V) input.

**Power Architecture:**

- VBAT → TPS54360DDA buck converter → +5V @ 3.5A

- +5V → SPX3819M5-L-3-3 LDO → +3.3V @ 100mA

- VDDA filtered via 120Ω ferrite bead

**Peripherals:**

- IMU: ICM-42688-P (SPI1)

- Barometer: BMP388 (SPI3)

- Magnetometer: QMC5883L (I2C2)

- GPS: SAM-M10Q direct mount (UART3)

- OSD: AT7456E with 27MHz crystal (SPI2)

- CAN Bus: SN65HVD230

- FPV camera input with ferrite filter

- USB-C with USBLC6-2SC6 ESD protection

- SWD debug connector

**Connectors:**

- 8-pin JST-SH motor outputs (DShot, TIM1/TIM8)

- 4-pin JST-SH receiver (USART1)

- 4-pin JST-SH VTX (USART2 + video)

- 2-pin buzzer

- 2-pin current sensor input with ADC filter

- XT30 ESC power and battery connectors

- Battery voltage divider → PA0 ADC

As this is my first PCB in KiCad, and it is a bit more complex, I thought it would be a good idea to ask for some feedback.

Mainly because I plan on keeping this open source, and I don't want to share something that's wrong.

The main IC is an STM32H745ZIT6.

PCB: https://github.com/alx-uta/Orthrus-TX/tree/dev/PCB

Schematic (PDF): https://github.com/alx-uta/Orthrus-TX/blob/dev/PCB/Orthrus-TX.pdf

(0 "F.Cu" signal "L1_SIG_TOP") -> Signal
(4 "In1.Cu" power "L2_GND") -> GND
(6 "In2.Cu" power "L3_POWER") -> Power
(8 "In3.Cu" power "L4_GND") -> GND
(10 "In4.Cu" signal "L5_ELRS") -> ELRS + Other signals
(12 "In5.Cu" power "L6_GND") -> GND
(14 "In6.Cu" signal "L7_ANALOG") -> Analog + Other signals
(2 "B.Cu" power "L8_GND") -> GND

I also had some good feedback from the KiCad community that I took into consideration.

(Please ignore the USB 3D model, as I couldn't find the right one.)

Thanks.

I have a pneumatic press connected to a couple of external PID controllers and timers, I have designed this schematic to allow a tidier solution than my current mishmash of wires.

The Arduino switches a bunch of relays, and then has a handful of 24V inputs, some sinking, some sourcing.

I'm hoping you could tell me if I have made any fundamental mistakes?

MCU - STM32L0

Battery - CR2032

Please check the schematic and the PCB and if there is any mistake please point it out. Thank You

Hey everyone,

I’ve been working on cramming a high end, battery-powered headphone amplifier and DAC into a tiny 70x30mm portable footprint. The goal is a good noise floor, 100mW into a 32-ohm studio headphones, and power switching.

I’m feeling really confident about the schematic and just finished the PCB layout (images attached). Before I send this off to the fab, you lot take a look at it for me please

This is my first time building something on kicad. I aimed to build a wearable smart watch. I got 0 DRC errors in the pcb editor. I think it's therefore, that it's flawless. Tell me why I am wrong and roast this as brutally as you can.

Hey everyone,

I’m currently working on an early prototype PCB for a wearable AI memory-capture device I’m building. The goal is essentially lightweight wearable hardware similar to the Meta RayBans that captures low-power audio/video and makes your life searchable with AI later (for work meetings, consent-friendly recording, etc). I want to emphasize that I am absolutely brand new to this, and I tried my absolute best to follow the strict review guidelines when making this post. Please call me out if I'm doing something wrong.

Schematic Link Here

This board is based around an ESP32-S3 and includes:

• camera interface
• microSD storage
• USB-C
• battery charging/power management
• microphone input
• status LEDs/buttons
• low-power sleep/wake behavior

I come from a software background & am an entrepreneur (Y Combinator), not EE/hardware, and this is my first PCB project. I had created a schematic and attempted basic routing, but eventually, I hired someone to help create the board/schematic in KiCad because I honestly didn’t know enough to do it myself at the time, but I’m now trying to learn PCB design properly so I can iterate faster and stop blindly outsourcing parts of the process. This PCB is the combination of my work & the outsourced hire. It's currently on its way from JLCPCB, but I am already thinking of many improvements I can make.

I’ve spent the last few hours trying to clean up the schematics/layout/images enough to make this reviewable according to the subreddit guidelines, but I’m sure there are still beginner mistakes here.

Main things I’d especially appreciate feedback on:

• ESP32 antenna/RF layout
• grounding strategy
• power routing / regulator placement
• USB-C routing
• decoupling / bypass capacitor placement
• manufacturability / assembly concerns
• anything that looks fundamentally wrong or risky

My goals:

• Reduce the overall length / size of the board
• Be very power conservative. Using a 500mah 3.7 LiPo battery & trying to get as much recording power as possible out of the wearable.

I attached:

• top copper view
• bottom copper view
• full routing/all copper view
• antenna + power closeups
• 3D renders
• schematic PDF

I’d genuinely appreciate blunt feedback. I’m trying to learn this properly rather than just treat hardware as magic.

Thanks in advance.

Hi All

Once again, I need a schematic review for sanity checking this supply. On the same PCB (though, electrically isolated if needed, see the jumpers on the top-sheet), I have three power supplies for an experimental setup we are making. One is a ±6V supply (directly from the manufacturer's eval board) for the Cremat Preamplifiers we are using, which I know works electrically. The second is a low voltage variable supply, from 0-24V (range is roughly, but should be precise to at least 0.1V). The third is a 0 to -4000V supply, precise to at least a volt.

The two variable supplies are used as biasing lines for the preamplifers (through AC Decoupling), and we are looking at, in theory, quite small signals, think hundreds of femtocolumbs, or 100mV signals on the highest gain amplifier. As such, both of these biases need to be extremely stable. This is the motivation for the design here, on both lines, as well as overall, and why you may notice a large number of components on the LV supply. Specifically, our expected rise times will be on the order of 10ns, so noise from 1/2 to 2x this value is what we specifically aim to remove, however, we still do not want kHz/GHz noise either...

Moreover, since I will be leaving the lab I'm working in, this is designed to be extremely serviceable, and as such is designed completely analog, and with only THT components where able.

I have a few specific questions:

1.) For the ±6V supply, do the components I have selected, assuming TO-220 THT packages, meet the thermal requirements for a 600mA overall load? My main concerns are, of course, the LM-317, which drops 24V to 16V, and the transistors. The transistors, unfortunately, look to be obsolete and are not THT, so I will need to choose something else of similar spec, but currently are (MMBT3904 and MMBT3906), which should be pushing the current. If needed, if these are TO-220's, I can attach heatsinks. I'm 99% sure they do, but a simple sanity check would be nice. Moreover, I also would appreciate THT suggestions for the transistors, if able.

2.) For the LV Supply, you may note that the voltage and current monitoring are on the output line... will this cause significant noise on my line? If so, is there anything I can do to mitigate this? Do I need to put the monitors somewhere else in the line, and if so, where?

3.) Furthermore, if able, for the LV Supply are there any THT replacements you can recommend for the OPA197? Not urgent, I can figure this one out myself if needed.

4.) For the HV Supply, which utilizes the HRC0524S4K0N as it's DC-HVDC converter, will the current filtering isolate the ripple noise? In theory, the HRC05 should keep it already down below 0.01%... In practice, though? The devices in aggregate should have, at most, a peak draw of no more than 50uA, for reference. If there is a issue, could you help me find a solution?

5.) Furthermore, assuming correct PCB design (which I know how to do), is this schematic safe to use? Are there physical safety concerns from the electrical connections, assuming an idealized implementation?

6.) Last, but certainly not least, are there any dumb errors you can see? Is something clearly not connected, or is there something I'll blow up if I plug this in?

Please let me know if you have any questions on components or specific requirements, etc, and I'll be happy to reply asap to the best of my ability. Thank you so much in advance!

This is a 2 layer motor shield for 6x brushed bidirectional DC motors, configurable from 4.5-25V (5A total) and 2x 5V servos (2A total), powered by 1S lipo or lifepo4 battery (charging circuit is off board).

Would appreciate a sanity check 🙏🏻

4.5-25V boost converter: https://www.ti.com/lit/ds/symlink/tps55340.pdf

5V boost converter: https://xonstorage.z8.web.core.windows.net/pdf/everanalog_ea2208t6r_apr22_xonlink.pdf

12x half-bridge: https://doc.awinic.com/doc/202312/832ca276-8e2d-4b06-8265-5702e7607ffc.pdf

Better resolution pictures in case reddit compresses too much:

kicad_screenshot: https://i.ibb.co/RkkSBBPV/blended.png render: https://i.ibb.co/XxRzm9sQ/motor-shield.jpg front copper: https://i.ibb.co/kV07mTQr/Motor-shield-f.png back copper: https://i.ibb.co/fVJDW3hL/Motor-shield-b.png schematic: https://ibb.co/xKXWb06C

Thank you!

Hey everyone. First-time PCB design here for a homemade digital watch project that I am working on. My hope is to make a nice 3D printed digital watch with an ePaper display. Any suggestions, improvements, or answers to my questions would be greatly appreciated!

I currently have a 4-layer PCB ((1)signal, (2)GND, (3)PWR, (4)signal). To give some more background to what I am working with, here is a list of my major components, their intended functions, and datasheets:

1. ATMEGA328PB-AU-ND (U1): my MCU on the board.
2. LSM303AHTR (U4): digital compass module. Intend to use this for a compass direction display on my watch. https://www.st.com/content/ccc/resource/technical/document/datasheet/1b/a1/fd/09/9f/41/44/cf/DM00177690.pdf/files/DM00177690.pdf/jcr:content/translations/en.DM00177690.pdf
3. XC6206P182MR-G (U3): LDO to step my 3.3V battery source down to 1.8V to power the above digital compass module (yes I probably should've found a digital compass that runs off 3.3V to save me the trouble). https://product.torexsemi.com/system/files/series/xc6206.pdf
4. PCA9306DCTR (U2): Level shifter to allow I2C between my 3.3V MCU and the 1.8V digital compass. https://www.ti.com/lit/ds/symlink/pca9306.pdf?ts=1757540593801
5. RV-8803-C7 (U6): Crystal oscillator RTC with temperature compensation. Using this for low-power timekeeping that only wakes up the rest of the components (via INT) every minute to update the minute reading on the display. Won't show seconds unless the user holds the button in order to conserve battery. https://www.microcrystal.com/fileadmin/Media/Products/RTC/Datasheet/RV-8803-C7.pdf
6. TMP117MAIDRVR (U5): Temp sensor. Placed it near the edge of the board. Intend to put a small port covered with a Gore-Tex membrane (to waterproof) near it for higher accuracy. https://www.ti.com/lit/ds/symlink/tmp117.pdf
7. TL6340AF160Q (S1): Edge mount button. Intent is to have the display show the temperature reading, compass heading, and seconds when the button is held. May come up with some creative button pressing scheme to allow setting alarms etc. https://configured-product-images.s3.amazonaws.com/Datasheets/TL6340.pdf
8. 89898-303ALF (J1): 6-pin ISP connector. Using this to do the programming on the board. May remove it after to save vertical space during installation.
9. BU2032SM-JJ-GTR(BT1): Coin cell holder. Currently have on underside of board.
10. 24 pin ZIF connector (J2): This is what introduces most of the complexity into my design. It is the connector that connects to my eInk display (ER-EPD0154-2) via ribbon cable. The eInk display has an on-board Display Driver (SSD1681) which requires an external voltage booster circuit. That is what necessitates the 3 diodes, transistor, inductor, etc near the 24 pin connector. https://www.buydisplay.com/download/manual/ER-EPD0154-2_Datasheet.pdf?srsltid=AfmBOoqM5LeeL7_UdtmfCszjST-iRqtlVPpcBnYFIvL_sQ7yFUJ9JqX6 https://cdn-learn.adafruit.com/assets/assets/000/099/573/original/SSD1681.pdf

Main Questions:

1. Does my voltage-booster circuit look correct? Are there any EMI concerns with it and the close proximity to all the signal traces nearby?
2. I resorted to running a lot of the signal traces between the 24pin connector and my MCU through VIAs and to the underside of the board so that the voltage booster lines could cross on the top signal layer. Is this a fine practice?
3. My second layer is an uninterrupted GND plane, and my third layer is 3.3V PWR plane. I've also poured ground on both signal layers. Is this best practice?
4. I drop some traces through vias to run through the PWR plane for a few connections. Is this best practice, or would I be better off dropping these to the bottom signal layer?
5. In a couple places I run traces underneath some components. Is this fine? I've heard a lot of different things from different people online regarding this.
6. I also placed some pull-up resistors and decoupling caps from the 24 pin connector onto the bottom signal layer in order to clear up clutter and fit everything there. Is this acceptable?

Thank you in advance for any help or advice! Excited to hopefully be get this printed sometime soon.

Hey everyone,

I'm currently working on a custom soundbar that is designed to be fully integrable into a smart home system. The main board features a total of four MCUs: one for a low-latency wireless subwoofer link, one exclusively for Bluetooth (with AAC codec support), one ESP32-S3 as the main Wi-Fi hub for Home Assistant integration (ESPHome), and finally, an RP2354 acting as a dedicated hardware DSP.

Since populating this finished board isn't exactly a cheap undertaking, I’d really appreciate it if some of you could take a look over the schematics and the PCB layout. This is strictly a passion/hobby project—I am neither an academic nor a professional EE.

The entire project, including the corresponding RX module for the subwoofer, is hosted here: https://github.com/babeinlovexd/Insane-Soundbar

Thank you in advance for any criticism, spot-checks, and feedback!

Hey all, a review for this project would mean the world to me.

The board is designed to hold a soft-core 6502 microprocessor, with plenty of peripherals to mess around with. The BIOS/code for the MCU will be appended above the FPGA config bitstream. The iCE40HX4k is capable of running USB with the nand2mario project, and it also has VGA and HDMI video output. I have used USB-C with a power-negotiation chip to deliver up to 10W, alongside a TPS54386 dual buck converter for deriving the 3.3V and 1.2V power supplies. I also use a diode to get 2.5V since it's flexible unlike the 1.2V supply. PS/2 uses level shifters to translate the 5V bus to 3.3V for the FPGA. I'm also using a 4M x 4B x 16Bit SDRAM for the on-board memory.

I've done my best to follow datasheets and best practices. Feel free to be picky with your review, and tell me anything that might need to get changed.

Thanks!

Hello!

I'm mostly finished with this DDR routing for the Allwinner A33. I'm only done and wanted to ask some questions.

The stackup is as follows:

L1-SIG

L2-GND

L3-PWR

L4-SIG

L5-GND

L6-SIG

A few questions I have are:

1. What's the simplest way to make a reference voltage for the VREFCA and VREFDQ pins on the DRAM chip?

2. Do I need extra components on the CK/CK# lines?

3. Will the signals on L4 be badly interfered with by the power islands on L3?

4. Will crosstalk be a large problem with the long parallel traces?

Thanks!

Hello everyone,

This is a continuation of my previous post asking for a review of my first PCB Design for this project. Like I said in my previous post, I am very new to PCB design and have been learning as I go, would love some feedback on my design, especially regards to the power circuit I have.

Stackup:

-Top Layer Signals + Components:
-GND Plane
-VCC (3.3V) Plane
-Bottom Layer Signals

Main changes:

- I realized from the EByte LoRa datasheet that 3.3V input would not achieve maximum transmission range and that I would need a 5V input to do so. Therefore I added in a boost transformer to have a consistent 5V supply for the LoRa, sine my input voltage from the LiPo battery is only ~3.7V. My concern with this is the length of the 5V trace and the BAT line from the LiPo connector cuts through the width of the board and might interfere with other bottom & top layer lines when peak current is reached during transmisson, ~1200mAh per datasheet.

- Is it a good idea to route the 5V trace as I did? I tried avoiding routing anything underneath the LoRa as per the datasheet as well. I did consider completely redoing the layout but thought I would close off this version as is then V2 would be focused on layout and routing improvements.

- I moved the GPS closer to the center edge as recommended by the datasheet. I plan on using a ceramic antenna to place directly underneath the GPS, hence the opening next the the U.FL connector.

- Double checked the GPS & LoRa datasheet, a GND copper pour underneath them is fine and with limited effect.

- Changed the Boot & Reset buttons to 90° mounted buttons for better access and smaller size.

- Added a via fence to the RF trace of the LoRa and checked with JLCPCBs impedance calculator to match the RF trace thickness with the 50 ohm impedance requirement, about ~1.5mm trace width.

- Made sure there was enough space for standoffs to be placed for a future enclosure.

- I made other changes as specified in my previous post by a few commenters, much appreciated!

A few question/concerns of mine now:

- Will the 5V trace be affected by the surrounding VCC copper pour or vice versa? What would be a good work around to this? I did consider a 6 layer stackup with 5V and GND2 as the 2 extra layers to avoid the long trace and use blind vias to connect the inner layer, but seemed like overkill.

- I have a few small copper pour GND "islands" but all are connected with at least one via to the GND plane, is this good enough to avoid parasitic interference? Or would proper via stitching be advised? Again, they are small, I pasted an image of the pour for reference. Would via stitching be advised for other reasons such as, for e.g., the 5V line cutting through the VCC plane

- Is there a general rule on spacing between traces of different types? Ive been following guides online, but they sometimes seem arbitrary?

Of course, any other suggestions or changes is much appreciated and thank you in advance!!

Edit: Just realized one of the LoRa corners overlaps with one of the screw holes of the OLED screen, will fix that!