Summary datasheet, 249 KB PDF, for a group of mega parts listed as 640, 1281, 1280, 2561 and 2562, matching the Atmel AVR ATmega640/1280/1281/2560/2561 family; the final number in the name may be a typo for 2560. Given its size it is the short edition with features, pinouts, register summary and ordering data. It is handy for identifying pins on these high pin count controllers. Use the full family datasheet for electrical and programming details.
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