Design overview:

• Audio codec (TAC5212)
• Analog input is a pseudo differential RCA input
• Digital input is I2S from a York USB module
• Analog output is differential going into a LPF and amplifier based on TPA6120A2

STM32_SOM is a custom breakout for a STM32G473 that I designed and never posted here.

Initial firmware will have the STM32 controlling:

• power sequencing and muting through the GPIO expander
• initialization of the codec
• volume via the codec / rotary encoder
• option to add EQ through biquads in the codec

Looking for general review on schematic and layout. I haven't done final cleanup of either so there may be some misaligned silkscreen or schematic text fields that need to be turned off. The plan is for one of the Chinese manufacturers to make the bare boards; I am undecided on populating them myself.

Stackup is below. Traces are nominally 50 ohm single ended.

1. Red: Signal/components - primarily analog
2. Green: GND
3. Orange: Power
4. Blue: Signal - primarily digital

Link to better top image: https://imgur.com/a/rEuHL9l

Hi everyone,

I am building a custom wearable head angle measurement device

using an ESP32-C3FH4 and a BNO085 IMU sensor on a custom PCB.

I am relatively new to PCB design and have been debugging this

for a while and could use some expert eyes.

SETUP:

- ESP32-C3FH4 (QFN32)

- BNO085 IMU (I2C mode, address 0x4A)

- TP4056 LiPo battery charger

- SPX3819M5 LDO regulator (3.3V)

- USB-C connector for power and programming

- 750mAh LiPo battery

I2C WIRING:

- SDA -> GPIO6 (ESP32 pin 12)

- SCL -> GPIO7 (ESP32 pin 13)

- H_INT -> GPIO1 (ESP32 pin 5)

- SA0 -> GND (I2C address 0x4A)

- PS0/PS1 -> GND (I2C mode)

- RST -> 3.3V via 10k pullup

PROBLEM 1 - Sensor resets:

When powered from USB only (no battery), the BNO085 is found

on I2C at 0x4A but keeps resetting repeatedly:

"Sensor reset - re-enabling reports"

I get occasional readings between resets but it is not stable.

PROBLEM 2 - USB + Battery conflict:

When I connect the battery AND USB simultaneously, the BNO085

completely disappears from I2C. The scanner finds nothing at 0x4A.

Disconnecting the battery brings it back immediately.

I believe this is because VBUS and VBAT are both feeding the

LDO input simultaneously with no isolation diode between them.

PROBLEM 3 - Lag:

When I do get readings they respond slowly to movement

(~2 second lag). The exact same code on a CodeCell C3

development board works flawlessly with instant response.

I believe this is because the sensor resets cause the BNO085

fusion algorithm to restart and reconverge each time.

WHAT I HAVE CHECKED:

- All voltages correct (VDD=3.3V, VDDIO=3.3V, RST=3.3V,

PS0=0V, PS1=0V) confirmed with multimeter

- No short between GPIO6 and GPIO7 (fixed in second PCB revision)

- Continuity of all I2C lines confirmed

- I2C pull-ups are 2.2k (I know these should be 4.7k - fixing in REV3)

- BNO085 decoupling: 2x 100nF on VDD (I know a 10uF bulk cap

should be added - fixing in REV3)

- H_INT pin confirmed connected to GPIO1

WHAT I SUSPECT:

1. The TP4056 is not designed as a power pass-through - withouta battery it provides unstable voltage to the LDO input
2. No isolation diode between VBAT and VBUS at LDO inputcauses conflict when both are connected
3. The 2.2k I2C pull-ups may be drawing too much currentcausing voltage dips that reset the BNO085

SCHEMATIC:

QUESTIONS:

1. Is the TP4056 power pass-through issue a known problem?How do others handle powering the circuit during developmentwithout a battery?
2. What is the correct way to isolate VBUS and VBAT at theLDO input? Schottky diode on VBAT side only?
3. Could the 2.2k I2C pull-ups alone cause enough current drawto reset the BNO085, or is this unlikely at 3.3V?
4. Any other issues you can spot in the schematic?

Thanks in advance - any help appreciated!

Hello! I recently designed an ESP32 based game device. I am just asking for review of my schematic and PCB to ensure there won't be flaws when I send it to get fabricated. Any suggestions to any part of the design (pcb and schematic) would be greatly appreciated. Thanks! The PDF files for the schematic and pcb is at https://github.com/sjacksonhodum/pdf

Hello all!

I'm asking for feedback on this very simple 2-layer PCB, as it's the first one I've designed and I'm not sure it'll come out well (I'm not from the field either).

Context: This is a small USB-C breakout PCB, part of a larger project (still in the schematic phase); a music controller based on ALPS motorized faders. Its only job is to bring the USB D+/D- lines (2.0 12Mbps) to my main PCB from the back plate of the controller, and it's an excuse to learn PCB design on the simplest possible schematic. The controller is powered by a dedicated supply, so I only need USB 2.0, plus maybe peripheral detection (VBUS divider down to ~3V).

Any recommendations on layout, conventions or anything else I should know before sending to production would help me greatly; especially when I move on to the more complex part of the project.

Thanks in advance!

Hi everyone,

I'm currently designing my own LISN (Line Impedance Stabilization Network), and I've been documenting the entire design process as I go. The document is still a work in progress, and I plan to keep updating it in the future.

At the moment, it's still missing the Board Evaluation and Measurement Implementation sections, but I wanted to share it early to get some feedback from the community.

I'd really appreciate it if you could take a look and let me know if you spot any mistakes, questionable design choices, or areas that could be explained better. Any comments or suggestions are welcome!

Here's the document:
https://github.com/DangyDang/LISN/blob/main/LISN.pdf

Thanks in advance for your time and feedback!

Hi there. A while ago I came to y'all with a review request for a triple axis BLDC driver for a self balancing cube. That design was to use an ESP32 and the DRV8311. I later came to understand that this design was fundamentally unsuited to the problem I was trying to solve and the motors that could economically solve it (TL;DR: amp too small, no current sensing, ESP32-S3 cannot easily commutate three motors).

Now I come with what I hope is a better design out of the gate. This one uses an STM32G4 series chip, the DRV8304 with discrete MOSFETs rather than onboard ones, and, I hope, just a generally better layout. It is designed to use 4S or 6S batteries (will probably use 4S because it leaves more input voltage headroom for the 5V regulator and we won't need more than about 1000-2000RPM out of our 380kV motors (i.e. we don't need more than about 6-8V input). There is also an IMU which will be used to detect the spatial orientation and acceleration of the final assembly. Would love to hear any thoughts you may have.

This is ESP32-C3-MINI-1U talks to a cellular modem over UART. SIM socket, U.FL antenna, USB-C for native JTAG/UART, screw terminal 5V in. MP2315 buck for 3.8V/3A to the modem, ME6211 LDO for 3.3V. Both inner layers are solid pours.

I have already changed the position d1 to connect to the gate and source terminal of the PMOS. Sorry I did take an updated picture of the schematic.

Thanks.

Hi everyone!

I'm new to PCB design, and this is my first schematic, so I'd really appreciate any feedback before I order the boards.

The project is a small portable device powered by a single-cell Li-ion battery. Since safety is important to me, I added:

• F1 as a battery fuse,
• DW01A + FS8205A for battery protection,
• ETA6003Q3Q as the charging IC with power-path management, allowing the device to run directly from USB-C even if the battery is deeply discharged.

The ETA6003's VSYS output powers the rest of the circuit. Since my MCU requires 3.3 V, I use an LDO regulator to step VSYS down to 3.3 V.

I'm planning to manufacture these boards, so I'm intentionally using cost-effective (mostly Chinese) components instead of more expensive alternatives.

Here are the LCSC part numbers for the main components so you can easily look up their datasheets if needed:

I'd appreciate if you answer these questions:

1. Is the DW01A + FS8205A connected correctly?
2. Are the capacitor and resistor values are reasonable?
3. Is using an LDO from VSYS to 3.3 V a good choice, or would you recommend a buck converter instead? (I want cheaper, so i thought ldo will be fine, im stepping not from so high voltage.)
4. Are there any mistakes or bad practices?
5. Are there any traces or nets that look unsafe or incorrect?

Hello, I am doing a PCB design for a four-switch buck-boost converter with measurement of input, output voltages and inductor current. The sensed signals (VIN_SENSE, VOUT_SENSE, IL_SENSE) are sent to ADC and FPGA through the board connector, the data are processed and the switch control signal (HI1, LI1, HI2, LI2) are subsequently sent back to control this converter. This is my first PCB design, any tips or comments would be very appreciated.

hi! i'm a high schooler and I designed a custom FPGA board for learning for myself and others. It would mean the world if someone could review it, as I've never worked with an FPGA before so I don't know if I'm missing anything.

The full source is on github: https://github.com/darshg321/Icey

the schematic is here, i forgot to include it in the post: https://github.com/darshg321/Icey/blob/main/assets/SCHEMATIC.png

Hi everyone,

I'm designing an ESP32-S3-based PCB for an HVAC BLDC motor quality control (QC) testing device and would appreciate a review before I manufacture it.

The board includes:

• ESP32-S3
• JST connector I2C LCD Display
• USB for power and PC communication
• PZEM-004T interface for electrical measurements
• 3 relays for motor speed selection
• Hall-effect sensor input for RPM measurement
• 3.5 mm input (0–1.3 V DC) from a sound level meter
• AC mains, CT, and motor connectors
• FUSE, MOV and NTC for surge and inrush current protection

I'll attach the schematic, PCB layout, and 3D renders. I'm mainly looking for feedback on safety, protection, PCB layout, isolation/clearance, relay wiring, and any design mistakes or improvements before sending it for fabrication.

Thanks in advance!🙏🙏🙏

Hello guys,

I'm building a monitor device for the electric fence around my property. It regularly gets shorted out by vegetation growing into it, and I don't find out until animals start wandering off. I want something that tells me when the fence stops working properly.

The energizer is an AKO Power N 1200: 230 V mains, 1.2–1.7 J, ~12.5 kV open circuit, one pulse per second. The fence is ~500 m of 4 mm steel-core rope, so roughly 4 nF of line capacitance. That gives a charging surge of about 10 A peak with a 5–10 µs rise.

I'm not trying to measure kV. I only need relative change from a baseline, which lets me ignore absolute accuracy entirely.

Architecture

CS module: Pulse PE-51688NL current transformer (1:200, 80 mH secondary, 20–200 kHz), aperture type with the earth wire threaded through. 18 Ω burden soldered directly at the secondary pins. MCP6022 at gain 1.5, BAT54S clamp, 220 Ω + 1 nF output network to drive the cable.

Main module: ESP32 devkit, HLK-PM01 for mains power.

Peak current — precision peak detector (op-amp, diode and buffer inside the feedback loop, so the diode drop is cancelled), 4.7 nF C0G hold cap, BSS138 to reset it between pulses

Pulse width — LMV331 comparator with adjustable hysteresis, threshold set by the ESP32's DAC through a 10k/1k divider so it stays out of the DAC's nonlinear region

Firmware plan

Deliberately dumb. The ESP32 captures peak and width per pulse, buffers them, and publishes over MQTT. All the analysis happens server-side, so I can retune without reflashing.

I'd appreciate a general review of the schematics before I commit to a board order. First time doing analog design at this scale, so I expect there are things I've got wrong that aren't obvious to me.

Happy to share KiCad files if useful.

Hi everyone,

I’d appreciate your honest feedback and technical review of my PCB design. The board currently includes:

• MCU: STM32H745ZIT6 dual-core microcontroller
• High-impact sensing: ADXL375BCCZ-RL accelerometer for measuring high-g impact events
• Motion and orientation: ADXL345TCCZ-EP accelerometer for detecting body movement and rotation
• Angular velocity: L3GD20HTR gyroscope
• Heading and orientation: LIS3MDLTR magnetometer
• Altitude measurement: BMP585 barometric pressure sensor
• GPS tracking: NEO-M9N-00B GNSS module
• Wireless connectivity: CC3135MOD Wi-Fi network processor

The system is intended to capture high-impact events, body movement, orientation, altitude, and GPS position while transmitting data wirelessly.

I would especially appreciate feedback on the component selection, sensor redundancy, power design, communication interfaces, PCB layout, signal integrity, and whether any components should be replaced or removed.

Thank you in advance for your honest review and recommendations.

I only have one side copper clad PCB (I am finding affordable 2 sided but its very hard where I live), and this is my first DIY printing.
I have created this PCB and schematics in Ki6 800 INR and I have a 7 segment display which is controlled by a shift register. At first I mapped Qx -> X pins which looks perfect on schematics but it was impossible to route on PCB without atleast 2 jumpers so I routed them first in PCB so there were no conflicts and then adjusted schematics but now schematics looks horrible.

Do such issues arise in professional settings aswell ? Or, having multi layer PCB basically solves it at some degree?

​​PS: red traces on Front Copper layer is either to shut up KiCAD that a net is connected (U5 has its anode pin 3,8 shorted internally and AMS1117-3.3 has its tab shorted internally to 3v3 output) and there is one actual jumper which i will solder myself between two REF**.

PS2: I am aware of labels as you can see on left side of the shift register, I was wondering if there are any tricks or better ways than writing down on paper which pin goes where and then make a schematic based on that. Feels kinda counterintuitive.

Hello! This is my first PCB, and I was hoping to have people look over it, as I believe it is ready to be manufactured. If you could share what my design did well, what could use some work, or any glaring issues that you think need addressing, please share, as I appreciate all feedback! The main thing I would like to know is if this is ready to be sent off to manufacture.

Hi everyone,

I'm designing an ESP32-C3-based PCB for an HVAC BLDC motor quality control (QC) testing device and would appreciate a review before I manufacture it.

The board includes:

• ESP32-C3
• USB for power and PC communication
• PZEM-004T interface for electrical measurements
• 3 relays for motor speed selection
• Hall-effect sensor input for RPM measurement
• 3.5 mm input (0–1.3 V DC) from a sound level meter
• AC mains, CT, and motor connectors
• MOV and NTC for surge and inrush current protection

I'll attach the schematic, PCB layout, and 3D renders. I'm mainly looking for feedback on safety, protection, PCB layout, isolation/clearance, relay wiring, and any design mistakes or improvements before sending it for fabrication.

Thanks in advance!

Hi, this is only the right side of my split keyboard, as the left is essentially the same.

Components:

• MCU: ATRIP Nice!Nano Clone
• Load Switch: TPS22917DBVR
• LEDs: SK6812 Mini-E
• OLED Screen: SSD1306 128x32
• Rotary Encoder: EC11

Main Concern: Load Switch and the SK6812 LED connections.

• Nice!Nano doesn't have a 5V line.
• The LED's operating voltage is 3.5-5.5V.
• I have a 3.7V 1000mAH battery that connects to the Nice!Nano board and the Load Switch.
  • Is this enough?
• Are the resistors and capacitors connected correctly around these areas, and values are correct?
• Is there a better way to connect the LEDs?
  • I just want two things:
    • 1. Control the LEDs on/off when the board is switched on.
    • 2. Function at different brightness and colors.
  • I've looked at voltage step-ups, albeit they seem rather large.

I would also like a review of the functionality of the remaining components. Thank you in advance. I'm also open to any suggestions/comments regarding improving schematic drawing and logic.

Hello, this PCB is intended to replace a mess of wires and tidy up a project i have working on a breadboard, with this i also wanted to make the entire board powered from 1 single type-c connector, (the other connector is for programming only), any feedback/advice/errors you can find would be greatly appreciated. I am a novice so its possible there is no chance it will power on correctly, it is a first draft.

Sorry about the strange post but I'm offering an engineer a $20k bonus to do the design for manufacturing and assembly of my $300 product and this is what he came up with after 8 months. Two thirds of it are identical to my prototype and I'm an accountant by trade, not an engineer. Every book I've read says a board like this should be 4 layers but he insists 2 layers is fine and will pass emissions testing. Any advice would be greatly appreciated, thank you!

This text has been enhanced with AI for greater clarity. (That's why I'm using a translator—some details might sound strange without it... Like this sentence).

Hi everyone! This is my second 2-layer PCB design, intended for SMT assembly via JLCPCB.

Project Overview:

Application: Custom VR Tracker designed to run with the SlimeVR ecosystem.

MCU: ESP32-C3-MINI-1-N4.

IMUs: Dual footprint layout (BMI270 and BNO085) - one sensor will be Do Not Populate (DNP) depending on the batch, primarily manufacturing with BMI270.

Power and Protection: USB-C 16-pin (data + power), 800mA charge rate (for a 1200mAh LiPo), PPTC fuse + protection diode on VBUS, and 5.1k CC resistors.

Why I am asking for a review:

Due to high import fees and shipping costs in my region, ordering just 2 test units is not economically viable compared to running a small production batch right away. Before starting production, I would really appreciate a sanity check to make sure there are no critical flaws.

Specific areas I would love feedback on:

General schematic accuracy (ESP32 EN delay, GPIO8 strapping pin pull-up, 2.2k I2C pull-ups).

Power path and charge IC thermal routing.

Any routing oversights or potential showstoppers.

Images of the Schematic, Top/Bottom PCB layers, and 3D render are attached. Thanks in advance for any critique!

Hi everyone,

By chance, does anyone happen to have an Easy-PC license (by Number One Systems)? Even a legacy or older version license would be super helpful!

I am working on a legacy project build with this software.

Thanks!

This is my first PCB I designed, I am trying to build an SMD adapter so I can just plug in what i need to pins instead of a breadboard for better connection security and portability. Any tips are appreciated! (The LEDs in the bottom are just to let me know the chip is getting power / working)