Datasheet in PDF form for the Atmel ATmega323, an older 8-bit AVR microcontroller with in-system programmable flash, EEPROM, SRAM and JTAG interface. The 2.10 MB document describes pin assignments, clock options, fuse settings, peripherals such as timers, USART, SPI and ADC, plus electrical limits. Repair technicians consult it to locate power, crystal and reset pins, verify signals with a scope, and set up a programmer for reading or rewriting firmware. Check the chip marking and package before relying on pin numbers.
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