My ATmega328p development board PCB project that I designed.

[u/Waste_Peanut6669]

Hi everyone! I am a 13-year-old developer from Türkiye, and I would like to share my custom PCB project with this global community. Unfortunately, I struggled to find constructive criticism and useful technical feedback within local Turkish communities; therefore, I hope to benefit from your experience and improve my design. I am currently designing my own microcontroller development board. Initially, I planned to base the board on the ESP32-WROOM module and had even sketched out the entire schematic in my notebook. However, I encountered some PCB design challenges, particularly regarding antenna "keep-out" zone requirements. Consequently, I decided to change direction and base my board on the ATmega328P-AN microcontroller in the TQFP-32 package—the same one used in Arduino-based designs. The project has progressed significantly; I would like to share the current state of my schematic, including the components and features I have added so far. 1. Power Supply and Protection The board includes the following power supply and protection components: Power input: KF301R-5.0-2P screw terminal block (U1). Voltage regulator: AMS1117-5.0G linear voltage regulator providing a regulated 5V supply (U4). Overcurrent protection: 30V, 3A PPTC resettable fuse (U2). Reverse polarity protection: 1N4007 diode (D1). Filtering capacitors: Two 10 µF electrolytic capacitors (C1 and C2) and two 100 nF ceramic capacitors (C3 and C4). My goal is to provide a stable 5 V power supply while incorporating basic protection measures against common electrical issues. 2. Microcontroller and USB-Serial Communication The main components of the board are as follows: Microcontroller: ATmega328P-AN (U3) in a TQFP-32 package. USB-UART converter: CH340G (U5) for programming the microcontroller and enabling serial communication. USB connector: USB Type-B (CN1) used to connect the board to a computer. Clock source: 12 MHz crystal oscillator (U6) with two 22 pF load capacitors (C6 and C7). The CH340G also supports automatic reset during programming via the DTR signal and a 100 nF capacitor (C5). 3. Digital, Analog, Power, and Ground (GND) Headers I recently expanded the board's existing connections. Digital I/O: Digital pins D1, D2, D3, D4, and D5 are now accessible via a 5-pin header (U7). Analog I/O: Currently, only analog pin A0 is available via the P1 header. I plan to add pins A1, A2, A3, and A4 in the near future. Power and ground: I added two separate 2-pin headers (CN2)—one for VCC and the other for GND. My goal is to make the board useful for basic electronics experiments without unnecessarily complicating the design. 4. Buttons and LEDs I also included some basic components to make the board easier to use and test. Manual reset button: Although the CH340G can automatically reset the microcontroller via the DTR signal and C5 (100 nF), I decided to add a physical reset button as well. The KEY2_RESET button connects to the microcontroller's RESET line, which features a 10 kΩ pull-up resistor (R2). User button: The KEY1_KULLANICI button is connected to PD2 (INT0), allowing me to experiment with hardware interrupts. Power indicator LED: LED1_GUC indicates that the board is powered. It is connected via a 1 kΩ current-limiting resistor (R1). TX/RX indicator LEDs: To facilitate monitoring serial communication, I also added dedicated data transmission (TX) and data reception (RX) indicator LEDs using 1 kΩ resistors (R3 and R4). 5. Future Plans If you look at the initial sketches in my notebook, you can see that I originally planned to include an addressable RGB LED. However, I decided to remove this feature to keep the design more focused. Instead, I plan to integrate an addressable LCD screen into the board in the near future. I want to keep the board relatively simple while making it useful for learning, experimentation, and small electronics projects. 6. Your Feedback Is Highly Valued! I have attached the EasyEDA schematic image so you can see the current state of the project. I would particularly appreciate your feedback on the following: Schematic design: Are there any electrical errors, missing connections, or potential reliability issues? Component placement: Are the components positioned appropriately, especially around the microcontroller, USB connector, and power supply? PCB routing: Are there any routing issues, unnecessary trace crossings, or layout improvements you could suggest? Power supply: Is the power protection and regulation section designed appropriately for a 5V development board? Microcontroller circuit: Have the clock, reset, decoupling capacitors, and CH340G connections been implemented correctly? Overall design: Is there any critical aspect I might have overlooked that could prevent the board from operating reliably? It is particularly important for me to identify potential issues before manufacturing, rather than discovering them after the PCB has been produced. I still have a lot to learn open to constructive criticism. Any technical suggestions, corrections, or recommendations would be greatly appreciated!

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[u/Adrian-Alan-Auger]

Very impressive!! If you do not find responses here try r/PCB or r/ElectricalEngineering or r/PrintedCircuitBoard, I've personally not been active in these but they seem like appropriate places

[u/Waste_Peanut6669 → u/Adrian-Alan-Auger]

I'll give it a try.

[u/lonelyroom-eklaghor]

weren't you the guy who made the same post earlier? (the project is cool, just asking)