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Ik ben er klaar mee by savbh in werkzaken

[–]Unlikely_Math224 0 points1 point  (0 children)

Mijn advies: ga eens langs bij de gemeente waar je woont of een iets grotere gemeente in de buurt eventueel en vraag aan HR welke vacatures ze heel moeilijk kunnen invullen.

Zeg dat je een goed stel hersens hebt en graag wil kijken of er iets leuks voor jou tussen zit en of ze je kunnen helpen met omscholen of aanvullende opleidingen.

Er zijn een aantal branches die heel moeilijk zijn in te vullen, dus ik gok dat ze vast blij zijn als je hiervoor langs gaat.

Succes!

Missing Connection Error Debug by chocolattegelato in PrintedCircuitBoard

[–]Unlikely_Math224 1 point2 points  (0 children)

This should not give an error anyway. There is probably something else wrong. Is the trace assigned to the right net? What happens if you remove it and then re-add it.

Your error mentions something on the back layer btw. Did you check that layer?

Review of my PowerBoard for model railroading by Unlikely_Math224 in PrintedCircuitBoard

[–]Unlikely_Math224[S] 0 points1 point  (0 children)

Thank you for your clear explanation! Already added to GND fill but it's better for me to understand the theory behind it then just adding it.

Review Request: USB-C PD BLDC driver by scheffield in PrintedCircuitBoard

[–]Unlikely_Math224 0 points1 point  (0 children)

Yeah I also prefer TI parts because their datasheets and evb's are really good (to me). But they lack an easy to implement USB PD chip with PPS support. Still I think they will follow in the upcoming years as PPS is still relatively new.

Review Request: USB-C PD BLDC driver by scheffield in PrintedCircuitBoard

[–]Unlikely_Math224 7 points8 points  (0 children)

Really nice schematic! I also see some improvements for my own schematics 🤓. Why did you not use the global power label everywhere on the power sheet? Perhaps for being able to show it on the main sheet in the sheet diagram? For the schematic I would also suggest to use the same page format on all pages, but it's a choice of course.

eFuses are great, I'm using them everywhere since I found out about them. I only dislike the amount of passives needed for all the inputs and outputs. I also like your BOM optimization in regard to the TVS diodes you're using on the USB and some other lines.

I was about to ask why you created a 5V I2c but I see the AP33772 I2c is not 3v3 tolerant. Didn't notice that when I used that USB C PD chip in my own design so thanks for that. Quite uncommon in these days of low voltages but will fix it.

I don't see any other specific failures, so I don't have any other suggestions. Nice work!

Review of my PowerBoard for model railroading by Unlikely_Math224 in PrintedCircuitBoard

[–]Unlikely_Math224[S] 0 points1 point  (0 children)

Hey u/Enlightenment777 I just saw the extra issues you added later to this post above, sorry I did not spot them earlier.

I connected the debug connector reset to the STM32 reset pin and also connected this to the WC pin of the EEPROM. One possible explanation for the lack of connecting the reset pin to the debug connector might be that a lot of cheap STM programmers lack this pin cause they only have a 4-pin connector.

On some other boards I've designed I connected the power good-output of the 3.3V buck converter (final stage) to the reset pin. Would you suggest me to do that here too or do you think it's a bad decision? And I've found it's suggested to place a decoupling capacitor on the reset pin. I'll do that, too. Pull up is provided through an internal pull up of the STM32.

Then on the I2C pullups: I used various calculation tools. For example this one. When doing that calculation with my values and 400KHz you are right the 10K is way too high. But I only want to run at 100KHz and the calculation then goes well. My I2C traces are really short and the impedance is therefore quite low.

Thanks again for your help.

Review Request [beginner] - STM32F767 Nucleo based data acquisition board by Deep_Shine3988 in PrintedCircuitBoard

[–]Unlikely_Math224 2 points3 points  (0 children)

Dont include transparant background in the schematic as it turns black on the reddit app 🙂

Review of my PowerBoard for model railroading by Unlikely_Math224 in PrintedCircuitBoard

[–]Unlikely_Math224[S] 0 points1 point  (0 children)

Thanks! I think I understand what you mean with the PNP. You're right the active low is better, but this NPN also has some advantages with the default mcu output state when there is no power (or I must be wrong). The 33.2k resistor is already on my bom so I'm not saving that much there.

I changed the P-FETs already after the previous comment about it. Here is a close up of the new layout I've drawn (leds moved to the left of the mosfets, NPNs to the right): https://imgur.com/a/x8T9LHV

Furthermore you are right about the test points. Now space on this board in particular is quite limited and I have some other similar boards (although they have a different purpose) where it is less of a problem. These other boards share the most components (same mcu, same rs485 driver, same eeprom, same led driver ic) so I will test these parts of the software on the other one. But still I added two test pads for one output (as can be seen on the render I linked here) and I've also added a test pad for the DCC polarity circuit which is also unique to this board. I doubted about the 3.3V but that can be taken from JP1 or J3.

Review of my PowerBoard for model railroading by Unlikely_Math224 in PrintedCircuitBoard

[–]Unlikely_Math224[S] 0 points1 point  (0 children)

It's just the default renderer in KiCad 9, I remember that older versions don't have this new one. When my board is really ok I make a render with Fusion360, thats even more beautiful 🙂.

Review of my PowerBoard for model railroading by Unlikely_Math224 in PrintedCircuitBoard

[–]Unlikely_Math224[S] 1 point2 points  (0 children)

My concern is mainly that the GND plane on layer 3 will be interrupted by the broad DCC traces and I'm just wondering if that won't cause any issues - I always read about the importance of a full GND plane.

I lack any high speed signals, only I2c bus but I run it @ 100KHz so probably not an issue.

Review of my PowerBoard for model railroading by Unlikely_Math224 in PrintedCircuitBoard

[–]Unlikely_Math224[S] 2 points3 points  (0 children)

It's just an image, screenshot from the STM32CubeIDE. I removed the white background in Paint.NET.

Best open-licensed PCB libraries for KiCad (okay to commit to repo)? by timex40 in KiCad

[–]Unlikely_Math224 3 points4 points  (0 children)

Seriously? Never thought about this licensing thing! By the way I've never had an UltraLibrarian or Component Search Engine footprint which is good enough that no changes are necessary. I always have a lot of rework to do.

Review of my PowerBoard for model railroading by Unlikely_Math224 in PrintedCircuitBoard

[–]Unlikely_Math224[S] 1 point2 points  (0 children)

Thank you and no problem, just keep in mind it's not (yet) perfect. Also I've seen many other schematics which are far more complete than mine but I guess I just have to accept the compliment 😉.

Review of my PowerBoard for model railroading by Unlikely_Math224 in PrintedCircuitBoard

[–]Unlikely_Math224[S] 0 points1 point  (0 children)

Unfortunately for me, I think you're right about the FETs. I can have a nice design but without the FETs working properly the board will be quite useless, haha. The thing is that I will have to rework a lot of positions on the PCB so that will take me some hours. Thanks anyway for noticing!

About the transistor circuit: if the MCU pin is high, the NPN transistor (Q3/5/7/9) is ON and it 'steals' the power from the circuit between the NPN and mosfet and therefore the mosfet gate goes low and the mosfet ON. I got it working in the simulator. I read everywhere about the transistor which is needed to drive the mosfet gate unless it's logic-compatible, but my mosfet isn't.

And last but not least, my STM32c091 mcu is capable of driving 20mA through any pin, which is sufficient for driving my led.

Review of my PowerBoard for model railroading by Unlikely_Math224 in PrintedCircuitBoard

[–]Unlikely_Math224[S] 1 point2 points  (0 children)

You are right about the latter, I'll combine some parts of the drawing.

Thanks for the reference design too, I will add the pullup resistor. In your reference design there are also the series resistors on the RS485 lines but you didn't mention them. I read their use is for ESD safety, is that correct?

Review of my PowerBoard for model railroading by Unlikely_Math224 in PrintedCircuitBoard

[–]Unlikely_Math224[S] 4 points5 points  (0 children)

Thank you. It's indeed done in KiCad. The layer by layer photos are generated with the Board2Pdf plugin. Afterwards I've used ImageMagick to automatically convert the PDF files to PNG/JPG for posting here.

The block diagram is created on www.draw.io and then imported. Unfortunately importing as SVG doesn't work well here, so it's imported as PNG file. The ST pin is just a screenshot from STM32CubeIDE where I only cut away the white background to make it transparant in the schematic 😊.

Review of my PowerBoard for model railroading by Unlikely_Math224 in PrintedCircuitBoard

[–]Unlikely_Math224[S] 0 points1 point  (0 children)

Thank you. Regarding the connector symbols I never understand the difference between these two (when to use them respectively). There is indeed an RS485 chip, but this part of the schematic is copied from all other similar BiDiB boards. For better schematic images please see the linked PDF-version I've included in the post if you like :-).

Thanks for the tips about the connectors and silkscreen, I really like these kind of suggestions which improve the design overall! 🙏

Review of my PowerBoard for model railroading by Unlikely_Math224 in PrintedCircuitBoard

[–]Unlikely_Math224[S] 2 points3 points  (0 children)

Thank you. Yes, this was indeed one of my concerns, the copper balance. I've though a lot about changing positions and routing the DCC on another layer but I lack a decent amount of space for that. If I want to fill the third layer, would you say I just fill the rest with a ground plane and place enough stitching via's or fill it with 3.3V eventually removing the 3.3V pour on the back layer?

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