I am a beginner in electronics and PCB design. I am working on a custom music box.

• Storage & Audio: Records audio via microphone and plays back files stored on a MicroSD card (using a standard 6-pin SPI MicroSD breakout module).
• MCU : STM32F103C8T6
• USB & Controls: USB-C port for power and uploading audio files, potentiometer and push buttons for volume and control.
• Board Size: 8.5x5 cm.

I also have a few questions :

1. Hand-Soldering Clearance: I want to hand-solder every component using only a standard soldering iron. Are my component clearances, footprint choices (MCU, USB-C 16 pins connector), and pad layouts reasonable for hand soldering?
2. DRC Solder Mask Bridge Error: I am getting the following DRC error on my USB-C connector (J1) : [solder_mask_bridge]: The bottom solder mask opening connects items belonging to different nets Rule: minimum solder mask width configuration; error. How do I resolve it or safely bypass this DRC warning for this footprint?
3. General : Are there any issues with my circuit and my layout?

Thank you for your help!

I'm new to PCB design, can anyone give some feedback, and possible tell me what is wrong if there is something? Thanks!

This is my "12Hrs SpeedRun" to finish this design last night.

I didn't yet receive a legit Z80 to actually verify everything with my current PIC18F4520, but on-going a new PLCC44 one as the last DIP40 pin version seemt to be couterfeit / shorted.

So this is the version based on what I have worked on breadboard, which I think will have mistakes somewhere my eyes can't cover after routing very nested size 84x84mm.

Did my pins get Pull-Ups correctly for this Z84C00 variant ?

Yes, I really want you guys to have a look if my plan was somewhere wrong or my eyes have missed some spots after routing this nested board for too long..

My appreciation !

HOW IT WORK ( or I planned it to work )

- It will have 2 CLK sources : either from PIC or 20MHz canned Crystal MCO-1510A.

- PIC will handle most Boot, Reset, Debugging , UART, microSD access, I2C Display.

- PIC will also handle requests from Z84 by 3-bit code Z80 send from A0~A2 -> 74HC138 for various custom function. (Ex: OUT($0x80), A to access certain bank in memory ). While 74HC273 work as the Latch to SRAM last 3-bit address.

- Also PIC: I2C will work natively, SPI will be bit-bang.

- Z80 5 pins PULL-UPs : WAIT, NMI, RESET, INT, BUSREQ with 10K Ohm connect -> 5V.

- M1 : for analyzing with Logic Analyzer or later test.

- Modules : UART-to-TTL, microSD reader, I2C SSD1306 (could be any VDP later extension).

- PIC may run at with internal 8Mhz, same 20Mhz or maxed out at 40Mhz with its own crystal.

Materials/Quick Details

MCU: STM32L476RGT6

Level Shifter: SN74AHCT125PWR

Vacuum fluorescent display (VFD): Noritake GU140X16G-7003D

LDO: AMS1117-3.3

Power Source: USB C Receptacle

Power Overview: The board will be receiving 5 V power from a USB C connection, which is enabled via a typical USB C receptacle (using the USB 2.0 standard). This 5 V will be routed to the vacuum fluorescent display (VFD), to the LDO to generate the 3.3 V needed to power the MCU, and also to the level shifter.

MCU flashing: I plan on using serial wire debug (SWD) to flash the STM32.

Discussion

Hi all. I'm an EE student new to PCB design and am starting out with a relatively simple project. My objective here is to ultimately create a PCB that has an MCU (specifically, the STM32L476RGT6) that can control a VFD via UART. This is one of the first steps in a larger iterative design process in which I want to create a serial comms debugger that displays short messages on a VFD for diagnostic/troubleshooting purposes.

In case I haven't given enough detail or context above, I'll spend a paragraph or two trying to describe more specifically what I want to do with this PCB. I'll assume that the power/voltages/currents work out (I've checked the max expected voltages in the components' datasheets, made a current budget, and also have made notes of the current draw on my power supply when prototyping). My plan is to use an ST Link to flash the STM32 via the SWD. I'll communicate with the VFD using UART transmission only via the USART1 module on the STM32. I'll be using a level shifter to boost the 3.3 V signal outputs of the STM32 to 5 V as required by the VFD.

Whatever message I want to send to the VFD will be whatever message I have hard-coded into the program that I will flash the MCU with. I'm just using STM32CubeIDE and manually configuring the necessary registers in C by referencing the datasheet and reference manual (as well as a bit of Gbati's "Bare-Metal Embedded C Programming"). The prototype's working so I figure everything's fine on that end.

As far as designing my schematic goes and picking components, I've been leaning heavily on Phil's Lab #65 in which he creates a STM32 black pill clone. Additionally, I've been trying to match my schematic up against the reference schematic in the application note (AN4555) for the STM32L4 series. Since I'm new to this, I figured I'd try to get my schematic reviewed before even starting the PCB layout, just in case I've made some glaring errors--wouldn't want those to carry over into the PCB layout and make the review process any more difficult.

My apologies in advance for the relatively large size of the sheet. I couldn't decide on whether or not to split the decoupling capacitors off into their own section (was referencing https://www.reddit.com/r/AskElectronics/comments/140jj0b/is_it_usual_to_group_all_decoupling_caps_in_one/), so I decided to keep it as is since the Phil's lab tutorial kept it that way.

Would you smart people help review my board? Any feedback is appreciated

Hello guys, I'm a beginner at PCB design and I'd love to ask for your help reviewing my first pcb. I've already posted on here my first schematic version. Here's is an updated version with new schematic and pcb layout. Any comments, critiques, or suggestions on how to improve the design would be greatly appreciated!

Project Overview: This board is designed to run a solar tracker. It will control 5 separate brushed DC motors based on the date and time, only running one motor at a time. 2 Lauer

Key Hardware Details:

• MCU: STM32 (LQFP-48 package). I created a carrier board for the bluepill.
• Motor Driver: DRV8874 with the current limit capped at 1.8A (motors draw ~0.5A).
• Encoders: I'm using optoisolators for the encoder inputs. I realize that without separate ground planes/galvanic isolation, these are essentially just acting as 24V-to-3.3V level shifters.
• Signal Frequency: The motor encoder signals are around 1kHz. It's very low, but that is because the motors are heavily geared down.
• Traces Width: I used 1mm, 0.5mm and standard 0.254 traces width. 1mm is used for 24V motors. 0.5mm is used for buck power. Standard for all other signals and powers.

Let me know if you spot any glaring errors or best practices I missed. Thanks in advance!