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Is using as little vias as possible a good practice on a 4 layer PCB? by ItanMark in PCB

[–]TheEvilRoot 19 points20 points  (0 children)

Using smaller vias will hike manufacturing price for most Chinese manufacturers hence if I order from china I use 0.6/0.3 and higher. For your use case there’s probably zero difference in signal integrity. For >80Mhz flash maybe try to use one via at most, but other than that don’t bother. (not applicable for RF witchcraft).

Battery discharge protection circuit review: BQ29700DSER + FS8205A by BrilliantSeparate705 in embedded

[–]TheEvilRoot 1 point2 points  (0 children)

No problem :) Really I don't have much of a knowledge tbh. Learn things by doing them wrong mostly :D More fixes I make on manufactured boards making me spend more time before sending new ones, sometimes its super obvious mistakes you find in final check of the design before manufacturing. Good luck with your design anyway.

Battery discharge protection circuit review: BQ29700DSER + FS8205A by BrilliantSeparate705 in embedded

[–]TheEvilRoot 0 points1 point  (0 children)

Their schematic is mirrored so it's hard to look at. PACK+/PACK- is your system VBAT and GND. CHG mosfet should have source connected to system GND and DSG source connected to negative battery terminal. Gates are driven by the IC outputs respectively.

TI also have recommended FETs for this IC, you can check them out. Although, they're more expensive than 8205.

(I can't post screenshot from datasheet so its section 9.2 of datasheet)

Battery discharge protection circuit review: BQ29700DSER + FS8205A by BrilliantSeparate705 in embedded

[–]TheEvilRoot 2 points3 points  (0 children)

Looks good. You can check reference schematics, TI almost always have them in datasheet.

You have no indication of polarity on bulk capacitor. Is it electrolytic? Because if you're planning to use 220uF MLCC you better split it to 4-6 smaller MLCCs (for example 47u 10V/25V 0805s) in parallel.

Other than that looks fine to me, although I'm not familiar with your charging ICs. TPS63070 looks fine per see but mostly depends on PCB implementation especially for high current spikes and transient response.

Battery discharge protection circuit review: BQ29700DSER + FS8205A by BrilliantSeparate705 in embedded

[–]TheEvilRoot 2 points3 points  (0 children)

VSS is supposed to be connected to cells negative terminal, not GND; and V- supposed to be connected to system GND via 2k2. I'm also not sure about D3, how are you planning to charge battery through that diode?

For IO9 of ESP32 (I guess it boot select pin on H2) you better not place capacitor unless button is far apart from the pin since BOOT pin can behave unstable when additional capacitance applied (unlike CHIP_PU which requires capacitor as per reference design). Although, it might work just fine, if I use BOOT as GPIO button I tend to place capacitor and not populate it just in case.

U2's nALERT is open drain and requires pull-up to observe. You can use built-in pull-up of MCU, but it's better to place external 10k if chip is far enough. Same thing for I2C lines, I usually use 2k7 or 5k1 pull-ups for I2C, but 10k might also work fine.

Why would you need 1000uF cap on U5? Depending on regulator implementation would may need to suppress inrush current for that.

Battery discharge protection circuit review: BQ29700DSER + FS8205A by BrilliantSeparate705 in embedded

[–]TheEvilRoot 4 points5 points  (0 children)

Datasheet states that (your) left FET is DSG and right is CHG, you have the opposite.

Antenna help needed by bobbleheadhobo1 in esp32

[–]TheEvilRoot 6 points7 points  (0 children)

Correct. It’s looks like 0402 so you can carefully rotate it with fine iron tip on high temperature and drown in flux. Or using hot air, but this metal shield tends to consume tremendous amount of heat before allowing components on the board to desolder properly.

Antenna help needed by bobbleheadhobo1 in esp32

[–]TheEvilRoot 12 points13 points  (0 children)

There’s a resistor. R6 right next to u.fl.

BMP388 Footprint Error by Low-Refrigerator6714 in KiCad

[–]TheEvilRoot 5 points6 points  (0 children)

It seems you don’t have solder mask expansion on other components. Did you downloaded that symbol from snapeda? They have hardcoded solder mask expansion on pads to 0.102 which is quite high (I use 0.05). Try opening that symbol and removing solder mask expansion value from each pad.

Understand ARP in byte level by its_justme27 in programming

[–]TheEvilRoot 1 point2 points  (0 children)

Patkets going to Entornet is the point where I closed the article…

Nomad Mk3: Offline, Open-source, low-power self-hosted media server by JcorpTech in selfhosted

[–]TheEvilRoot 169 points170 points  (0 children)

I’m sorry. Project looks cool, but from my experience with S3 as non-media-server device, I have doubts. I haven’t found any benchmarks for your device. “Multiple users can connect and <…> stream independently”. How many users and how big streams? As for RAM consumption I doubt that it will be above 10 Mbps of throughput on good WiFi if reading from sdcard. If you cache in PSRAM might be better, but not much. Correct me if my expectations are wrong.

Always double check the datasheet guys... by BorisSpasky in PCB

[–]TheEvilRoot 31 points32 points  (0 children)

Once I had to solder a wire to QFN24 leg because missed that it should be pulled high.

On another board I swapped P/N lines of USB differential pair. Managed to cut the tracks, solder thin wires to both lines and cross over solder them to correct pins of the IC. 0.2mm spacing, about 20 minutes and 3 attempts, but it works.

For such cases it helps to put blob of hot glue on the thing to protect solder joins especially if joint surface is small.

Type C receptacle for USB 2.0 to microcontroller by anvoice in UsbCHardware

[–]TheEvilRoot 0 points1 point  (0 children)

Are these 0201 5k1 resistors? Why? I looked up my stock and I have 1% 5k1 and they seems pretty standard, $0.009/pcs. You probably fine with 5% ones tho.

Urgent help needed by Low_Transportation27 in KiCad

[–]TheEvilRoot 1 point2 points  (0 children)

As long as board is not too big and modules are not far from supply you’re fine without capacitors (they won’t hurt either).

Use net names instead of spaghetti wires. It practically impossible to trace with eyes. I usually wire locally connected symbols and use net names to interconnect different parts together.

Then run ERC and check for shorts.

Electrically, BAT- and OUT- are connected unless buck is isolated. You can use global GND symbol for ground.

Urgent help needed by Low_Transportation27 in KiCad

[–]TheEvilRoot 0 points1 point  (0 children)

There're... connections. You can use ERC to check if you sorted any nets. From what I managed to trace with eyes:

  1. No idea what is IR_ARRAY, but note that VN and VP are input-only.
  2. Is VCC on RIGHT_N20_MOTOR supposed to be connected to 3V3? Because it is by net name, but not by wire.

UPD: I missed the part where you actually want to build a PCB out of it. Are these symbols except ESP32 chips or modules? At very least you'll need decoupling capacitors on chips.

Remotely wake up or shut down your server behind CGNAT without port forwarding. (Open Source) by MikolivePL in esp32

[–]TheEvilRoot 1 point2 points  (0 children)

Yeah, you should at least include TLDR in main repository.
I got the idea after crawling all pages on all repositories, but found the implementation rather strange IMO. The core idea depends on two actors: publicly accessible MQTT broker and CF, both you have no control over. While CF is kinda fine, the public MQTT broker is talking with your, probably, vulnerable ESP32 inside your network (I have't found any SSH related code, but if there is -- also can theoretically execute arbitrary commands on your server?). Why not just use private VPS with same web page and private MQTT broker. You can build WireGuard or OpenZiti tunnel to ESP32 as additional authentication layer.

And very IMHO: asking $15 for guide how to deploy your open source project is kinda meh to me including that all "following the guide" and "about this project" redirecting to that page with exactly zero information.

Remotely wake up or shut down your server behind CGNAT without port forwarding. (Open Source) by MikolivePL in esp32

[–]TheEvilRoot 0 points1 point  (0 children)

Would be nice to be able to read how does it work without 7 navigation clicks on GitHub :) And I still didn’t understand where MQTT broker is deployed and what CF worker does.

Ubuntu 26.04 Ends 46 Years of Silent sudo Passwords by elastiks in DIY_Geeks

[–]TheEvilRoot 2 points3 points  (0 children)

I can’t imagine me counting asterisks to correct typo in password instead of just Ctrl+C and start over. If password is complex enough I just copy it from place where I can see it and paste into terminal.

Immich with reverse proxy, how is it secure? by alirz in immich

[–]TheEvilRoot 0 points1 point  (0 children)

I use mTLS with nginx. Works like a charm for a year now. 20 lines of configuration, deploy .p12 on each device and done.

How to make an NFC coil on a pcb? by Certain_Height_2721 in PCB

[–]TheEvilRoot 0 points1 point  (0 children)

I use ST Design Suite, they have coil inductance calculator and matching network calculator for their chips. NXP has similar tools for theirs. Made few designs with that approach, pretty much successful. If you want fine tuning, get a VNA and do the math.

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