TL;DR: I'm recreating the Serial Loopback project from Make: AVR Programming on an ATmega328p. The UART echo works fine, but the LEDs on PORTB do not display the ASCII value of the ASCII received character. PB1 is always on, PB3 flashes for no clear reason, and the rest stay off. At this point, I’m stuck. Looking for advice on what I’m doing wrong. Obviously, I’ve missed something. I just don’t know what. Hardware setup MCU: ATmega328p on a breadboard LED driver: PORTB (PB0–PB7) drives the bases of 8 transistors. LEDs are wired as high-side switches — the long lead (anode) is connected to +V, the cathode connected to transistor base Transistors: 7× BC547 + 1× 2N2222 (same pinout) Programmer: USBasp, flashed via Programmer's Notepad USB–serial adapter: — possibly a counterfeit, but the UART side of things works, so I don't think it's the issue. Terminal: YaT on Windows The fritzing. I have created the circuit irl. This is not a simulation!…