Microchip family datasheet for the PIC18Fxx2 group, a 5.74 MB PDF covering several PIC18 microcontrollers that share one architecture, with the xx standing for the different memory and pin-count variants. It documents pinouts, oscillator modes, peripherals, configuration registers and electrical characteristics. Technicians use it to find ICSP connections, verify supply and clock pins and understand configuration bits before reprogramming a controller. Identify the exact part number on the chip, since flash size and package vary within the family.
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