i've created an all in one controller board for a turtle bot. it includes an ESP32-S3, two channels of audio in and audio out, two motor drivers, and an 25W USB PD output to power an rpi 5 at full power. all fit in a 4 layer 88.9mm x 88.9mm (3500 mils x 3500 mils) board.

i have tried my best to keep the power circuitry seperate from all the sensitive circuitry, and also keep the power traces thick enough to carry current for two waveshare DCGM-3865 motors.

the audio inputs expect an INMP441 module, i decided to go with an external module so that i am not ending analog signals through a long wire.

This circuit is supposed to enable communication between an ESP32 and Dynamixel motors. The TX_EN signal is supposed to be used to swich between sending / receiving data from the motors. I would appreciate it if someone could take a look at the circuit. TX_EN is supposed to be idle LOW. For now I am using a simple buffer to shift the TX_EN signal from 3V3 to 5V. Is this the best way of doing so or is there a better approach to this that also keeps the line idle LOW ? Any advice is appreciated!

Hi Team,
I've been working on making a PCB that goes from my 40pin Speeduino (Car ecu) connector to a AMP superseal connector (6437288-3)
The idea is to have a more robust mount than what i currently have, and 3D print a better enclosure.

I downloaded the footprint and symbol for the connector form Ultra librian, and made the other 2 myself.

It's a 4 layer board, with Power on layer 3, Ground layer 2, and signals Layer 1 and 2. Power and ground is 1.5mm, signals are .4mm

I gave it a go manually routing, but ended up using the KiCadRoutingTools plugin to make this.

I'm sure there might be a more optimal Pin to Pin order than what i've used, I played around with a few.

Any feedback is much appreciated!

Thanks

Hi everyone,

I've designed this PCB for an automotive project and I'd appreciate it if someone could take a look at the layout before I send it for manufacturing.

The board takes 12V from the car, filters and limits the input, and then steps it down to 3.3V using a buck converter rated for 1A.

The board reads a differential speed sensor, calculates the fuel level using a resistive sender (3 ohms when full and 61 ohms when empty), and uses a High Side Power Switch to power the fuel pump.

The estimated current consumption on the 3.3V rail is around 150mA.

I'm not entirely sure about the copper areas and power routing, so I'd like to get a second opinion on a few things:

• Do the copper regions look correctly sized for the expected currents?
• Is there enough copper around the power components for heat dissipation?
• Would you increase the width of the main 3.3V branch, even though the estimated current consumption is only around 150mA?
• Does the overall layout look reasonable, especially around the input protection, buck converter and fuel pump power switch?
• Is there anything in the layout that could cause problems with noise or interference when reading the differential speed sensor?

I'm still learning PCB layout, so I'd rather catch any obvious mistakes now than after ordering the boards.

I've attached the schematic and PCB layout for review. Any constructive criticism or suggestions would be greatly appreciated.

Thanks in advance!

High-res images

KiCanvas

GitHub

Hey! I've just finished up this SBC for my Linux audio player project. Reviews are really appreciated!

Components

• MPU: SAMA7D65, it can boost up to 1GHz, good audio subsystem and gpu
• RAM: Half a gig of DDR3L(MT41K256M16TW)
• EPD: Sharp MIP LS022B7DH03, can go up to 70Hz, 240x320
• Audio: TI TAC5212 CODEC, 192kHz 32bit
• Two Jacks: One single-ended 3.5mm with mic, and a balanced 2.5mm
• Wireless: Bluetooth 6 with LE audio and WiFi 6E (u-blox MAYA-W386-00B)
• USB: USB 2.0 with OTG
• PMIC: Microchip MCP16502AB
• BMS: TI BQ25640
• Fuel Gauge: Analog Device MAX17260
• Two Micro SD Slots: One for the OS, and one hot-swappable for media

PCB

• 0.8mm: I chose this for thinner pp so I can get thinner impedance-matched traces
• 6L Two Core
• SIG/GND/PWR/GND/GND/SIG
• 3h spacing for DDR 0.25mm

More info

This is my first PCB with DDR memory/an MPU, and this is my most complex design yet, so I might have messed up something basic

I do this as a hobby, and don't have a degree in EE yet

3 days ago I posted here asking for advice on my first PCB project and I received the most constructive feedback I've ever received on the internet. You guys helped me tremendously. Thank you.

I have implemented all of the suggestions I received and I am very pleased with the outcome. Instead of a massive, complicated, and extremely dense single-page schematic with no net labels, I now have an easy-to-read multi-page schematic that splits all of the different parts of the board into different pages. It is so much easier to read, and the use of net labels in the software simplifies things.

Doing this, I was able to find a few electrical errors in my original schematic, which I corrected in the process. I'm pretty sure that I have everything correct, but I would like the internet experts to review my schematic for any possible electrical errors, things I should add, or possible challenges.

To reiterate, this is a Transmission / Cruise Control Module designed for the Aisin AW4 transmission found in various Jeep and Toyota vehicles. It is powered by a Raspberry Pi Pico 2 and uses a 12-volt to 5-volt buck converter circuit to power the Pico. It has six 12-volt to 3-volt divider circuits for 12-volt input signals from the range sensor, brake switch, reed switch, and 4x4 switch. It also has six low-side MOSFET driver circuits to trigger relays that will activate shift solenoids for the transmission, control torque converter lock-up, and vacuum solenoids for the cruise control. I have eight logic-level inputs for paddle shifters and cruise control switches. I have also implemented a CAN module using SPI and a bidirectional voltage level shifter. There's also a breakout area for all of the leftover pins on the Pico where I will be putting a prototype area.

This board will be housed in a custom-built aluminum case next to my Speeduino ECM. Both the ECM and the TCM will be wired internally to the same ground-side-controlled fuel injection relay circuit from the key-on battery power. The TCM will receive multiple data points from the ECM over UART, where the Pico will translate everything over the CAN network.

One of my main concerns relates to fluctuation in battery voltage. Battery voltage can fluctuate between 12 and 14.5 volts, and the main 12-volt system could experience occasional heavy loads up to 400 amps with high inductive spikes up to 100 volts from a winch. I think this ultimately could be avoided by using a secondary battery for heavy loads, separated from the main system by a battery isolator.

Any advice would be greatly appreciated.

I submitted this board a couple weeks ago for review and got flamed for some questionable design choices, so I redesigned it, reducing the via count by 50.

This is a 4-layer design for a STM32f4 based flight computer intended for low-high power rocketry. The board has 4 pwm outputs for servo control, and pinouts for UART, SPI, I2C, and 3.3v. For sensors, the board uses two IMUs and an altimeter. The board also has two terminals to connect and light e-matches. These terminals have basic continuity detection, and power is toggled via a MOSFET.

Once again, any help will be greatly appreciated, thank you in advance.

Hello,

This is my first PCB, i am not fully done i still need to get the rest of the ESP pins to like a header pins or something so i can access them for LEDs and so on if i wanna add back and front light on the car.

But i would just like some feedback before i continue so if i can change something out for better performance or a cheaper part or if maybe my design just wont work i would like to change it now before it gets to complex?

I am a little lost and this is my first attempt so any tips even general PCB ones would help.

I have worked on ESP32s and L298Ns before to build a WIFI controlled car and not i am trying to design a board that is both of them in one. I decided to change the L298Ns to the ones on the Schematics because they are apparently a bit more modern and higher performance.

Thank you in advance !

Hi everyone!

This is one of my first more complex PCB designs, I would really appreciate it if someone could take a look and let me know if they spot any issues or areas for improvement.

Project overview

I’m designing an on the water rowing computer that provides information a rower will need when they are on the water

The main sensors are:

- GPS for measuring speed.

- IMU for calculating stroke rate.

Current PCB stack-up

1. Signal
2. Ground
3. Ground
4. Signal / 3.3 V

I would especially appreciate any feedback on the PCB layout, routing, grounding, power distribution, as this is my first time routing a 4 layer board.

Thank you so much for taking the time to have a look! Any advice would be massively appreciated.

Hi! First time designing a 4-layer board around an LGA SiP, so I'd appreciate a review before ordering (JLCPCB PCBA, both sides).

What it is: the electronics of a pen-shaped camera (16 mm tube). Press a button → ESP32-S3 wakes from deep sleep, powers the OV5640 (AF) camera, takes a JPEG, sends it over WiFi to the phone hotspot, powers the camera off and sleeps again. ~10–15 s per cycle, the rest is deep sleep.

Board: 27 x 10 x 1.6 mm, 4 layers (JLC04161H-7628: F.Cu / In1 solid GND plane / In2 signals + VSYS + GND pour / B.Cu), 0.1/0.1 mm track/space, 0.45/0.3 mm vias, LF-HASL.

Main parts:

• U1 ESP32-S3-PICO-1-N8R2 (LGA-56 7x7, 0.4 mm pitch, bottom side), 5 GND vias in the EP between 4 paste windows
• Camera: Hirose FH34SRJ-24S-0.5SH (J1, top), OV5640 24-pin DVP (Maix-Bit pinout), 2.8 V from SGM2036-2.8 (U5) enabled by GPIO35 (100k pull-down → camera fully off in sleep); SCCB pull-ups and the AF VCM supply go to the switched 2.8 V rail, not 3.3 V
• Power: TP4054 charger (100 mA, 200 mAh cell = 0.5C), power path AO3401A (battery → VSYS) + RB168MM-40 low-leakage Schottky (USB → VSYS), TLV75733 3.3 V 1 A LDO
• Sensing: VBAT/2 (1M/1M + 100 nF) → ADC1, CHRG → GPIO33 (10k pull-up), USB present divider 33k/47k → GPIO21 (RTC wake)
• RF: LNA_IN → 0R (L1) → U.FL, optional shunt C5 (DNP), external FPC antenna. Trace 0.18 mm on B.Cu over the In2 GND pour (h = 0.21 mm), ~6 mm (~55 Ω CPWG / ~70 Ω microstrip)
• Wire pads for battery, USB-C breakout board, button, RST/BOOT/3V3

Status: DRC 0 errors / 0 unconnected, schematic parity 0, ERC 0. Routed with Freerouting + scripted fan-out (the schematic is generated by a script, hence the label-heavy style — sorry).

Things I'm unsure about / would love feedback on:

1. LGA-56 0.4 mm on the bottom with HASL: OK for JLC, or should I go ENIG? Thermal pad: 4 paste windows (~49 %) + 5 via-in-EP (plugged).
2. RF trace is ~70 Ω microstrip (0.18 mm) instead of 50 Ω; only ~6 mm long. Worth widening near the U.FL?
3. Power path (AO3401A gate on USB_5V with 100k pull-down + Schottky): any issue with hot-plug or reverse current?
4. Only 2 x 10 µF (0402) + 1 µF/100 nF on 3.3 V near the SiP. Enough for WiFi TX bursts from a LiPo through a 1 A LDO?
5. Anything in the camera connector fan-out / pinout that looks wrong?

Hi,

I've been designing a castellated system on module style RP2350A board - much like the ESP32 boards you see from Espressif, that I've not really seen an equivalent of for the RP2 series MCUs. The closest would be the RP2350 stamp, and size-wise, closer to the Seeed Xiao, but with more pins available, and everything on the board edge.

This board is smaller and deliberately has less features, i.e. runs specifically off 3.3V, no on board LDO, no LiPo charging, no onboard buttons. No USB. But, it exposes all the relevant pins from the RP2350A, all the IO pins.

Basically, you provide 3.3V and GND, plus anything else you need, run the USB traces to the edge of your board, put in a bootsel or reboot button as required.

But it's 18x15mm. And it's designed with a number of my own projects in mind where I need a minimal footprint, but without having to deal with 0402 components! The idea is that these will be assembled by the fab house, (on a panel with appropriate fiducials).

This is a 4 layer stackup, L1 Signal/L2 GND/ L3 Power + GND/L4 Signal + GND. And I'm not exactly sure about that part. The relevant bits of GND plane are reasonably well stitched by virtue of the components, and I wanted there to be an element of reference plane for the signals on L4. I deliberately removed the plane from L1, as it was causing issues with the grounds I'd put into L2 with vias. I'm not sure about its presence on L4.

Due to the, particulars, required by the RP2350 around the internal SMPS and the inductor layout, I've laid this out to match the design guide examples as much as possible.

It's a small board, and to fit everything in, the power traces are 8mil and signal traces 6mil.

So largely, I'm looking for any feedback you might care to give functionally on the schematic, although I'm fairly happy with this matching the reference example. The layout, particularly about the ground planes, but also any concerns about component placement, routing etc. I've also attached a pinout diagram.

Thanks for having a look!

The purpose of circuit is: A person hit/press or lightly touch a piezo sensor, it creates an interrupt to our pin. Device likely be an esp32 or stm32 I did not decided yet, with usage of hardware timer on interrupt pin. My piezo is capable of giving out as much as 100V and as low as 1-2V as I measured from oscilloscope.

So I wanted to protect it from overvoltage via BT54S Schottky, and because of I used single supply comparator as I understand I should make piezo not 0V. So I added that circuitry for that.

The dual 22k resistors(R3,R4) is LLM's idea, as i understand it wanted me to create a physical seperation and because our current is so low but voltage is high, low value resistors is not a problem.

Hello, this is the third time I have had to remake the PCB, due to insightful feedback. And I will do it as many times as it takes.

The duration of this project is getting embarrassing, but I have genuinely learned a fuck ton, enough to fly past a hardware design interview and become a Level 1 Hardware Designer in this soulless job market.

I'm once again pleading for a review to continue my journey toward true competency in Hardware Design.

Project: 60–65 W Isolated AC/DC USB-C Power Delivery Wall Adapter

The objective is to design, manufacture, and validate a functional USB-C wall adapter. I have been using manufacturer reference schematics and datasheets to understand the reasoning behind each component selection, electrical connection, and PCB layout decision.

Electrical Specifications:

• Input: 90–265 VAC, 50/60 Hz
• Output: USB-C Power Delivery, 5 V / 9 V / 15 V / 20 V, up to 3 A
• Maximum output power: Approximately 60–65 W
• Topology: Isolated flyback converter with synchronous rectification
• Main controller: Power Integrations INN3879C-H801 (InnoSwitch3-PD)
• Transformer: Custom flyback transformer, ETD29/16/10 ferrite core (3C97)
• Target primary magnetizing inductance: Approximately 220 µH
• Switching frequency: Controller-dependent; approximately 70–140 kHz was considered during preliminary transformer design
• Secondary synchronous rectifier: AONS62922 MOSFET
• Primary protection: Fuse, MOV, NTC thermistor, bridge rectifier
• EMI filtering: Common-mode chokes, X-class capacitor, and Y-class capacitor across the isolation barrier
• Primary clamp: RCD clamp network to manage transformer leakage-inductance voltage spikes

PCB Specifications:

• Four-layer PCB
• 1 oz copper
• Dedicated primary and secondary ground regions
• Reinforced primary-to-secondary isolation, targeting approximately 8 mm creepage where applicable
• High-current nets routed using wider copper traces and polygon pours
• Attention to high-dV/dt switching nodes, high-dI/dt loops, thermal management, and EMI
• Design and layout completed in Altium Designer

A significant portion of this project has been learning how to properly interpret component datasheets, understand transformer behavior, select semiconductor devices, calculate current requirements, design snubber networks, enforce PCB design rules, and distinguish between electrical connectivity and an electrically sound layout.

What I specifically need reviewed:

1. Primary-side layout: Placement of the bridge rectifier, bulk capacitors, controller, transformer, and RCD clamp. Are the high-frequency current loops sufficiently compact?
2. Transformer and isolation: Primary-to-secondary creepage and clearance, copper separation across all four layers, transformer pin spacing, and placement of the Y-capacitor.
3. Secondary-side layout: Synchronous rectifier placement, transformer secondary connections, output capacitor placement, and whether my high-current polygon pours are appropriately sized without unnecessarily increasing EMI.
4. Grounding: Separation of primary and secondary returns, secondary ground distribution, and whether any copper pours create unintended coupling or compromise isolation.
5. USB-C PD circuitry: CC1/CC2 routing, ESD protection, VBUS distribution, and connector implementation.
6. Thermal performance: MOSFET heat dissipation, current-carrying capability of traces and vias, and whether the board has sufficient thermal copper.
7. EMI/EMC: Input filter layout, switching-node copper area, transformer coupling, and anything likely to cause conducted or radiated emissions problems.
8. Component selection: Voltage/current derating, capacitors, diodes, protection components, and anything that looks questionable before I spend money manufacturing this thing.

THANK YOU IN ADVANCE. I used IPC-2221, the clearance table. The PCB was designed with a target of approximately 8 mm primary-to-secondary creepage separation, following reinforced-insulation design principles under IEC 62368-1

following this datasheet: https://www.power.com/sites/default/files/documents/RDR-838_60W_USB_PD_3point0_3point3-21V_PPS_output_InnoSwitch3-PD_PowiGaN_INN3879C-H801.pdf

Hello everyone,

I hope you are all doing well.

I am currently working on a project schematic/layout and would really appreciate it if experienced engineers could take a quick look and review it.

Since I am eager to learn and improve, any feedback, advice, or suggestions from your practical experience would mean a lot to me.

Please let me know if you’d be willing to take a look, or feel free to leave your comments below.

Thank you so much for your time and help!

I feel silly asking basic questions having been in the electronics industry for 10 years, but I'm more on the systems side and trying to get back into the hardware stuff as a hobby.

I'm trying to design some test equipment. The DUT reads a resistance across two terminals and determines whether it is in a good range or not. The test equipment is basically as serial controlled relay board. Nothing complex.

Because the range I am trying to emulate is as close to dead short as possible up to about 7 ohms. I made a first design which works great but I used too thin traces and having some of the relays up to 100mm away from the connector meant the variance between channels was unacceptable (dead short was reading in the DUT low resistance range etc.). I need to fit 16 channels on a board. So there will have to be some distance on the traces. (I've measured the relay coil resistance and its minimal compared to the trace).

My steps for rev 2 have been:

• drop an intermediate connector and go straight to a DSUB connected to the DUT
• move to 2oz copper on the outer layers
• up the trace width to 1.5mm
• move to a 4 layer board to optimize traces for control lines, to not disturb the feed and return of each channel (top and bottom layer).

My question is, I need to fan out the DSUB row, I know this is only a very small distance but I want to do everything I can to reduce resistance. Can I do as I've done in the picture above, neck down between the pins, use copper on both sides of the board, and run vias to link them together for the short distance? Am I opening myself up to issues? Is there any other advice? Everything I'm finding about increasing trace width is all about carrying more current, but I'm only looking at a few milliamps, its the resistance that matters to me!

(Blue bottom layer, Red top, Kicad standard colours!)

Adding information for clarity:

The DUT is doing the resistance measurement, it provides 2 pins, feed and return and I am varying the resistance to test all states. Basically it provides a diagnostics state

• Anything under 0.7 Ohm = Short
• 0.7Ohm - 1.7Ohms = Low Resistance
• 1.7Ohm - 3Ohms = Value Good
• 3Ohms - 7Ohms = Resistance High

My main issue was the trace resistance impacting the measurement between Low Resistance and Short and for the very relays, Good and Low Resistance. I can't do large pours as there is 16 of these simulators per board. (32 traces for feed and return). How do the vias impact resistance? Does the current pass through just one, or can I stitch top and bottom traces together?

Ima high schooler who is designing my first dev board (and kicad project really). Any suggestions / issues would be greatly appreciated!

Hi all, it's my first attempt at designing a PCB of this scale, I've made this schematic and designed it according to this Instructables Guide and referring to the datasheet. I want to get this manufactured, but since the main STM32 H7 IC itself is a tad bit expensive, I didn't want to jump to manufacturing it without knowing for sure if it'll work or not.

I don't have that much experience designing PCBs, and this is a pretty huge deal for me, so I'd definitely appreciate your opinions on my choices, or check of there's any obvious mistakes you can spot.

Thank you!

Edit: Thank you all, I've gotten a lot of amazing feedback from a lot of you, I've made some changes that are hopefully better.
Top Layer
Bottom Layer

Major changes include:

1. Changed VBUS capacitance to 10uF
2. Moved both oscillators to the bottom layer, I know it isn't the best decision to do so but that was the closest they could be moved to the pins.
3. Poured ground over the top layer too, and stitched it as much as possible.

Let me know if there's something else to add!

Hi, this is my first more complex PCB project and I would apriciate a review before ordering from JLCPCB (I know the layout is kinda messy)

What it does:
Battery powered device that measures time of run with ToF sensor, the results are shown on 1.3 OLED display and android app. The communication is made with the android app, few LEDs and ESP-NOW (there are 2 measuring blocks, one for start, one for finish). The whole PCB will go into plastic ASA box.

Main Parts:
ESP32-WROOM-32
Li-ion 21700 cell (maybe i will use different one)
TP4057 (battery charger)
DW01A + 2 MOSFETS (battery protection)
TPS62A02 buck converter 3.3 V
CH340C USB-UART with two-transistor auto-reset
ToF sensor
OLED display
Battery tempeature control system (NTC + NTCR1)
Battery % system (ADC, R16, R17 => code will decide the %)
Buzzer, LEDs

Specific things I am not sure about:
Buck convertor layout
Battery protection
Auto-reset circuit
ESP32 antenna placement
SCL and SDA pins (AI told me to connect it like that but I am not 100 % sure about it)
Anything else that could make the PCB not work

Finished my very first schematic design! What do you think? All suggestions and comments welcomed. Looking to improve.

I'm currently designing my first purpose built PCB for a Raspberry pi project that I'm working on. I'm looking for some internet experts to scrutinize and review my schematic. Does it look okay? Are there any errors? Is it going to be functional?

This is a transmission control module with six divider inputs to drop 12 to 14 volt inputs down to about 3 volts.

It also has six low side mosfet driver circuits with flyback protection to control 6 external relays that will operate transmission solenoids and cruise control vacuum solenoids.

It has a 12 volt to 5 volt buck converter to power the Pico 2 and provide 5 volt reference

It uses a can transceiver with a 4-bit bidirectional voltage-level translator IC.

It uses a molex MX 150 20 pin connector to connect to the vehicle harness and we'll use a screw terminal block for 12 volt power and ground.

There is a breakout area where I have access to the CAN, 12 volt, 5 volt, 3.3 volt, and ground rails as well as the remaining pins on the Pico.

There are also several inputs for cruise control buttons and paddle shifters.

This unit will be housed in a custom built aluminum case paired with a speeduino ECM. They will both share grounds and be powered by an external fused ground side controlled relay circuit from their screw terminal lugs wired together inside the case. The main power and ground will enter the case through the main plug that is not on this board.

Everything is going to be through hole packages except for the voltage level translator integrated circuit. I'll have to sharpen a piece of copper wire and wrap it around my soldering iron to mount the integrated circuit.

Any advice would be greatly appreciated. 😁

Hi all, I'm designing a test board for a 160 W BLDC fan motor. It uses an ESP32-S3 with three temperature sensors, a differential pressure sensor, a display, an SD card, and an RS485 Modbus connection to a Selec energy meter. Speed is set by three triac channels (low, medium, high) switching the mains through optocouplers. Power comes from USB 5 V through an AMS1117-3.3.

The schematic is attached. I'd like feedback specifically on:

RS485

• Transceiver wiring (MAX3485), DE/RE# control, and termination
• Bias resistors for an idle bus and whether they're needed on a short run
• TVS placement and ground reference

Mains section

• Fuse and varistor order, and the NTC for inrush from the BLDC controller
• Triac and optocoupler choice (MOC3063/BT136 vs. 800 V parts), and the gate resistors
• Snubber placement across the triac (I've left them unfitted for now)

EMI, clearance and leakage

• Clearance between mains and low-voltage nets, and whether my slot and spacing plan is enough
• Creepage and leakage on the optocoupler and triac side
• Common-mode and radiated EMI risks from triac switching, and any filtering I should add

General

• Are the connections right? Anything you'd change before a PCB spin?

I'm not an EE, so plain feedback is very welcome. I'll post the PCB layout once it's routed. If anyone wants high-resolution photos of the board or the schematic, here’s my Drive link: https://drive.google.com/drive/folders/1faougHNje7w3B6eu84qCuEpPya0Ccdzw?usp=sharing

Hi! Reposting with some changes as well as pictures that actually attached lol. I'm looking for a review of my 4 layer board designed to characterize the charging and discharging of battery packs. I'm getting it fabbed and assembled.

Main architecture/functionality:

• A LV battery pack connects to the board 12s/50.4V max (this board does not replace a BMS or charger)
• A raspberry pi acts as the master for the board and communicates over USB 2.0
• An automotive relay selects a load path. This allows the battery to be discharged via an onboard electronic load or an external load
• The battery begins discharging at 25A max, and pack voltage and current are measured. Optional 12 external thermistor channels for the battery pack.
• Data can be stored over NOR flash or streamed over ethernet
• The electronic load is 4 parallel NMOSes with active control in the linear region. It can dissipate 300W maximum. The zero drift op amps must be powered with an additional 12V power supply.
• The STM32G474 is responsible for datalogging, as well as controlling the electronic load when it's in use. It controls the electronic load via a DAC signal. The analog read of the total current measurement is also used to implement hard OCP (hardware on STM) and soft OCP (FW based).
• The hard OCP is based on a comparator signal of the current that is compared against an analog signal generated by the STM as well. This means the hard OCP threshold can change, and allows flexibility in changing the hard protection to be constant OCP, varied OCP, or even hard protection from dissipating too much power through the electronic load (set mathematically, current * vbat)

Review Request:

I am a student and this project has a lot of new things I have never done before, so any advice is welcome. However, I am especially interested in the following:

1. I have a lot of analog on this board as well as high current. Do my return paths look okay? Do I have too many via transitions on sensitive lines? Is it too messy under the MCU?
2. How problematic is the ground loop off-board caused by grounding from two different power supplies (12V PSU + Raspberry pi) do I need to isolate one of them?
3. Additional checks: Ethernet layout and routing, QSPI, the absolute mess under the MCU (that inevitably violates clearance for USB and QSPI?), stitching
4. Foresight into potential MCU and firmware hardware issues (first time using an STM32 and little FW experience)

Additional info/clarifications:

• SIG/GND/PWR/SIG, though there are some signals on L3 under the MCU and GND is poured on all 4 planes
• There is a thermal design for the 300W dissipation and the load switch
• Battery discharge path happens on the left side of the board.
• The intention behind the extra protection circuits on the relay switching is that it is an automotive relay that is rated for high enough current but not voltage. The D latches are protection to make sure that the relay does not switch paths while the load switches are closed, which would cause it to fail by arcing voltage.
• The values for the type 1 compensator are more than likely not correct. I need to rerun the loop shaping model since the last time I did that part and I plan to tune values once I have board in hand anyway

Thank you!!!

Schematic: https://drive.google.com/file/d/1GnCGz3uy6ZfRXx3ex427GVQWzzrVI01y/view?usp=sharing

I am designing a control and switching board based on an ESP32-H2 to control the navigational lights on board of an old boat which I am renovating.

For reference and orientation I have included overview schematics in order to show the final project in its operating environment. The projects consists of two physically separated parts: the control board and the load-switching board. They belong together and their design needs to be coordinated.

The control board realizes a finite state machine (FSM). Upon pressing one of the illuminated push buttons on the front panel, the ESP32-H2 transits into the corresponding state, enables the confirmation LED of the push-button and disabled/enables the navigational lights for that operating state.

The load-switching board receives the signals of the control board and actually drives the navigational lights. The load-switching board uses high-side switching as the electric net on board is a minus-grounded DC net, i.e. the minus/ground must remain connected at all times.

The power supply is a 12V nominal LiFePO4 battery. The real supply voltage varies between 12.5V (when battery is depleted) and 14.5V (during bulk charging). There is no engine starter nor alternator connected to the battery, hence cold cranking is not an issue. Still wires runs extend up to 15m and hence voltage spikes and induced voltages may be a concern (especially as some wires run along the main sailing mast).

The entire system consists of two self-designed parts:

1. The control board
   • It is placed near the helmsman at the stern
   • It is mounted in the same enclosure as the front panel with the push buttons and confirmation LEDs
   • In essence, it contains
     • a step-down converter from ~12V to 3.3V based on the TI TPS62933P
     • multiple bidirectional input/open-drain output lines with level shifters; those receive the push button events and also drive the signals to the load-switching board
     • PWM outputs for the confirmation LEDs within the push button
       
2. The load-switching board
   • It is placed near the load center and battery
   • It drives the actual navigational lights
   • It contains the high-side switches which are driven by the control board

The cable between the control board and the load-switching board is 11m LiYY 12×0.5mm² (AWG20). The wires from the load-switching board to the navigational lights is up to 15m SIF 2x2.5mm² (AWG14).

The attached schematics are as follows:

1. An overview drawing (for reference only)
2. The top level schematics of the control board
3. The step-down converter/voltage regulator
4. The MUC
5. One of the eight level shifters (LS); it is used in 2. as LS 0, LS 1, LS 5, LS 11-14, LS 25
6. One of the five PWM outputs; is is used in 2. as PWM 1-4, PWM 22
7. The front panel with the illuminated push buttons (for reference only)
8. The load-switching board
9. One of the six high-side switches used in 8.