Hello everyone!
I’m new here, I’m a software engineer but I started to learn more about PCB design and electronics given the fact that I worked with PCB / electronics designers in my previous company.
I designed my FIRST schematics that “apparently” should work. I just want to be able to boot ESP32-S2 MCU and upload a program over the USB (I don’t need SPI, I2C or whatever).
So, please, is there a possibility someone could point me what (and why) is wrong with schematics (both the power supply and MCU design) and also what and how to fix if possible, please?
I also tried to replicate my first power supply (3V3) in Multisim and according to Multisim, it should work. I used LM1117DT and similar Schottky diode in Multisim as there is no AMS1117-3.3 component and no SS14 diode but it should be close to it.
I do have a ground connection on regulator (blue line).
VBUS will be USB input. ESP32 should have USB power supply 5V to 3.3V and also it will be used for programming the MCU.
Can you, please, check the other things? Would this work the way I imagined it should work?
And yes … +3.3V above PIN 2 on regulator is what I saw on internet (for KiCAD), I’m actually not sure if this needs to be here.
You mean that both MCU (ESP32) and power supply should work?
ESP32 as I mentioned must be able to boot and be programmed, that’s all what I want for now.
P.S.
I added capacitors on USB connector between VBUS and GND for noise supression.
And additional question: how reliable is National Instruments Multisim for simulating “real” circuits?
I wouldn’t want Multisim to show “everything OK” but when I make PCB to make it explode.
I think the resolution on the image is not adequate to show the fine line.
I am not sure I can see the problem. As for lighting the LED, what is the forward voltage rating on that LED? Some white LEDs may need > 3V forward voltage.
What are U2 and U3?
What is the purpose of the schottky diode D3? Might the power supply at VBUS be reversed (negative?)
IMO it’s a waste of time and money designing yet another MCU module based on a popular chip such as the ESP32 series when you can buy them mass produced for not much money. Remember too you would have to design the antenna as this MCU implements WiFi, and also assemble the board with SMD components. If you’re getting it assembled you’d be up for parts procument and assembly costs. Better use your money and effort towards designing some sort of peripheral board connected to the ESP32 module if IoT interests you.
Nobody simulates a simple circuit such as a LDO regulator, unless you’re the LDO chip designer. Just copy the circuit from the reference design in the datasheet or application note. In fact those commercially available ESP32 modules with a barrel socket would already have a regulator on board.
Finally this topic is starting to stray into advice for circuit design, and away from the use of KiCad wihch is the focus of this forum.
Ooops, I did not see that I switched + and - on USB.
It has bulk capacitors (but they are not seen on the picture).
1k5 resistor is connected to 3V3 line (so ‘pulled up’).
Also, its no 1n but 100n capacitor that is connected to CHIP_PU PIN over that 100n capacitor to the ground for resetting the ESP32.
As I said, I’m a software engineer so I’m often doing some hobby projects at home
(which you could also call “waste of time”) …
SMD components will be soldered by JLCPCB, why would I do that manually?
It doesn’t cost millions. Even if I spend 100$ it’s not much if I learn something given the fact I’ve never done it. I have some electronics knowledge from school but I forgot alot of things.
The purpose of this circuit will be learning first and secondly I want to make a temperature regulator for my central heating. I have an old Vaillant VRT30 temperature regulator which I want to replace with my own designed PCB which will have a relay and ability to be remotely controlled.
I know I could buy an assembled device and just mount it, but that’s not what I want.
I’d have more satisfaction if I make my own product that works!
Also, forum is about KiCad (that is a PCB / circuit designer) and I did not see that is forbidden to ask from the people who obviously know more than me what is wrong with my circuit and ask for help.
Better check the price of assembly and components with your fabricator and compare with the price of modules out there and see if you are willing to pay the premium.
This is not a general electronic design forum, even if the tool for design is KiCad. We have to concentrate on questions about the use of KiCad otherwise we would be flooded with questions about design. There are other forums for that.
OP and people who are willing to help with design questions can continue using the private message facility of this forum.
I’m here since 2017. Because all people asking here electronic questions were send mainly to go to EEVblog few months ago I decided to be also there.
At the beginning it looked that you have typical KiCad users problem with PWR_FLAGs (I don’t have problem with them as I never run ERC) but later it turned to not connected in any way with KiCad electronic problems.
No one mentioned it yet, but…
I have never seen capacitor being connected by switch to microcontroller pin !
How times are changing?
When I was young it could be my budget for several years of learning electronic. Then later working as academic teacher it was more than my half year salary and
Well, regarding capacitor connected to PIN over the switch … I’ve seen it on Google and they said something about parasitic something that it is used … I’m not sure …
I always put my bypass and bulk caps at the chip symbol. I find it annoying when they are off in a page corner. That’s just my ocd practice, but then I can see at a glance that things are correct:
My point about the pullup is that 3.3 should point up – it is a positive voltage. Ground and negative voltage symbols always point down. They never point sideways either. It is just good practice for readable schematics. Signal flow should be left to right when possible (eg: analog filter page of opamps…).
On digital stuff it is a bit squishier as signal direction varies. I make symbols for micros and such to group ports together as I like them, and signal directions vary of course:
Your wacky cap/pb reset is an antenna just asking for creating random chip resets as it picks up noisy crap or esd sparky-sparky events. Don’t do that. A chip reset usually has a weak internal pullup (eg 100k or so). It is bad practice to leave them open. I like to add a 10k or so pullup, and optionally a 0.01 or 0.1uF cap to ground (which holds reset low for a little bit at power up). Pushbutton is optional across the cap. An open-drain supervisory chip is another option you can add which resets when 3.3 sags during a brownout:
Yeah, sometimes folks here try to shut down electronic design questions, and many times the questions asked are just goofy and the posters have no idea what they are doing and don’t implement suggestions. But hey, everybody starts somewhere. I have designed electronics and pcbs since the 80s, but when I go to the freecad forum where I am asking newbie questions about an area that is new to me, I appreciate the thoughtful help from the experienced people there.
I think this question leads easily into kicad schematic design practices and it is an opportunity for us to show examples of how we do things to help new folks learn.
Also, don’t forget to add a place to clip scope gound – I like to use a 2-pin 0.1" header. Don’t forget mounting holes. Add descriptive labels on silkscreen for connector names… Always have some ground plane.
Not sure who you are asking, but the regulator is fine with the 22 and 0.1 caps on in and out. Schottky not really needed unless you add a second one from a second 5V input (then the diodes isolate the two supplies, like usb and a dc barrel jack). Verify that in and out pins on the layout match the datasheet as the ams1117 has a goofy pinout (with tab being output)…
Where did you get this esp32-s3 symbol? I always make my own so unsure what is in the provided libs. I didn’t check all of your symbol pinout but I don’t see pin 3 (second VDD3P3) or pin 56 (second VDDA). You are leaving the pin-29 VDD_SPI pin open – it can be an in or an out, so I will presume you are planning on using it as an out. You do need some bulk cap (one or two of the 22 uF) and a 0.1 at the power pins.
You need to fix the d+/d- thing (one end is wrong). Adding 22 or 24 ohm series resistors in those lines is also normal.
And you need to fix that reset circuit as mentioned above.
and 
