Introduction

PIC series of controller high performance, low cost RISC controllers. It is based on Harvard architecture allowing use of separate instruction and data buses. The architecture allows a typical 14 bit wide instructions word length and 8-bit data width. Being RISC controller, it supports only 35 instructions and all instructions except jump and branch instructions execute in single cycles. It has large number of registers arranged in banks of register. The number of register banks depends on the PIC family and the type of controller. A quick comparison is given below:

PIN Diagram of PIC16F877 controller

PIC 16F877 comes in 28, 40 and 44 pin packages. Table below shows different types of packages, pin count and the pin diagram are shown in table:

PIC16F87x packages, Ref: http://ww1.microchip.com/downloads/en/devicedoc/30292d.pdf
Package Type	PIN count	Pin diagram
Plastic Dual In-line Package, or PDIP, is one of the most mature plastic IC packages still in use today	40
PLCC Plastic Leaded Chip Carrier is a form of SMD IC package	44
A quad flat package (QFP) is a surface-mounted integrated circuit package with “gull wing” leads extending from each of the four sides. Socketing such packages is rare and through-hole mounting is not possible	44

This controller operates at 20MHz, Power-on reset (POR), Broun-out reset(BOR), 8Kx14 program memory, 256 byte EEROM and 368 bytes of data memory (RAM), 14 interrupt sources, five ports Port A,B,C,D,E; three timers, 2 CCP module, MSSP, USART serial ports, PSP parallel slave peripheral, 10-bit ADC module and 35 instructions. The 40 pins of the PDIP package  PIC16F877 is described below: