An ATMega developer works on the ATMega microcontroller series of Atmel Corporation, now owned by Microchip Technology. They design, program, and implement embedded systems using C, C++, or Assembly language. Their responsibilities include creating and debugging firmware, interfacing with various hardware such as sensors or actuators, and optimizing system performance. They also work on power management for low-power applications and ensure system reliability and security. Additionally, they often collaborate with hardware engineers to develop circuitry compatible with the ATMega microcontroller. They may also develop software tools to assist in microcontroller programming and testing.