Developing atmega2560 arduino compatible custom board still failed

hi guys!

i’m now developing my own board that running on atmega2560. Basically, i want to create my own custom PCB.

i take +5V to all of atmega2560 VCC,AVCC, and AREF pin and take the 0V to all of the GND, AGND pin. In my design, i didn’t give a lot of bypass caps. Only 10uf electrolytic caps between +5V and GND. In this state, i’m not install the external clock ,because i know that AVR will run on 8mhz internal clock in the first time.

i’m happy with my hand soldering. i’ve test it with my multimeter and there is no any short circuit.

Once i connect my board to the power source, it created some smoke. immediately i remove the power source and test it with my multimeter, and now it show about 7-20 ohm resistance between 5V and GND. it’s like a closed circuit.

i’ve re-check my soldering visually and there is no any join. i’m expecting this caused by the atmega2560 itself. Maybe i have some mistakes in my design or how the first time i need to handle atmega2560 incorrectly.

Really need help. Thanks.

Here is my own schematic

pss: sorry with my english

Problem found! It's located on my very simple power supply. AMS1117 5V broken when hit 2A 12V or when it does a shorting circuit power supply. So, it not putting out 5V. It just putting out 12V directly to microcontroller.

Can someone give me a better idea about power supply? Stepping down 12V to 5V with 2A? Thanks

12V to 5V at 2A? The LM2576 is very useful. The output is adjustable, but the 5V configuration is easy. It can handle 3A.