ATMEGA328P-AU by Microchip: 8-bit RISC CPU, 20 MHz clock, 23 I/O lines. Ideal for industrial applications with SPI, TWI, USART connectivity and low power mode. Features include 2048 RAM bytes, 1024 EEPROM size, and 16384 ROM words.
SMMBT3904LT1G by Onsemi is a NPN BJT with 3 terminals, 0.3W power dissipation, and 40V max collector-emitter voltage. Ideal for small outline applications requiring a transistor with hFE of at least 30, it operates up to 150°C and has a transition frequency of 300MHz.