PIC is a family of Harvard architecture microcontrollers made by Microchip

Technology, derived from the PIC1650 originally developed by General

Instrument's Microelectronics Division. The name PIC initially referred to

"Peripheral Interface Controller".

PICs are popular with both industrial developers and hobbyists alike due to

their low cost, wide availability, large user base, extensive collection of

application notes, availability of low cost or free development tools, and

serial programming (and re-programming with flash memory) capability.

Microchip announced on September 2011 the shipment of its ten billionth

PIC processor.

PIC16F877A is a latest Enhanced Flash Microcontrollers From Microchip.

The Key Features are

The Device has its Internal Architecture as shown in the Block Diagram

Below.

PIC16F877A is very popular because of its affordable price. Apart from that

it is also very easy to be assembled. Additional components that you need to

make this IC work are just a 5V power supply adapter, a

20MHz crystal oscillator and 2 units of 22pF capacitors.

Special Microcontroller Features

- 100,000 erase/write cycle Enhanced Flash program memory typical

- Self-reprogrammable under software control

- Single-supply 5V In-Circuit Serial Programming

- Watchdog Timer (WDT) with its own on-chip RC oscillatpr

- Programmable Code Protection

- Power-Saving Sleeping mode

Peripheral Features

- Two 8-bit (TMR0, TMR2)timer/counter with Prescalar

- One 16-bit timer/counter

- Brown-out detection circuitry

- Parallel Slave Port (PSP): 40/44 pin-device only

High-Performance RISC CPU

- Only 35 single-word instructions to learn

- DC-20MHz clock input

- Up to 8K x 14 words of Flash Program Memory

- Pinout Compatible to other 28-pin or 40/44-pin

Analog Features

- 10-bit, up to 8-channel Analog-to-Digital Converter (A/D)

- Brown-out Reset(BOR)

- Two analog comparators

- Programmable on-chip voltage reference (VREF) module

CMOS Technology

- Low-power, high-speed Flsh/EEPROM technology

- Fully ststic design

- Wide operating voltage range (2.0V to 5.5V)

- Low-power consumption

Pin Description

Pin Number Description

1 MCLR/VPP

Pin Layout

2 RA0/AN0

3 RA1/AN1

4RA2/AN2/VREF-/

CVREF

5 RA3/AN3/VREF+

6 RA4/T0CKI/C1OUT

7 RA5/AN4/SS/C2OUT

8 RE0/RD/AN5

9 RE1/WR/AN6

10 RE2/CS/AN7

11 VDD

12 VSS

13 OSC1/CLKI

14 OSC2/CLKO

15 RC0/T1OSO/T1CKI

16 RC1/T1OSI/CCP2

17 RC2/CCP1

18 RC3/SCK/SCL

19 RD0/PSP0

20 RD1/PSP1

21 RD2/PSP2

22 RD3/PSP3

23 RC4/SDI/SDA

24 RC5/SDO

25 RC6/TX/CK

26 RC7/RX/DT

27 RD4/PSP4

28 RD5/PSP5

29 RD6/PSP6

30 RD7/PSP7

31 VSS

32 VDD

33 RB0/INT

34 RB1

35 RB2

36 RB3/PGM

37 RB4

38 RB5

39 RB6/PGC

40 RB7/PGD

All PIC16F87XA devices have a host of features intended to maximize

system reliability, minimize cost through elimination of external

components, providepower saving operating modes and offer code

protection. These are:

• Oscillator Selection

• Reset

- Power-on Reset (POR)

- Power-up Timer (PWRT)

- Oscillator Start-up Timer (OST)

- Brown-out Reset (BOR)

• Interrupts

• Watchdog Timer (WDT)

• Sleep

• Code Protection

• ID Locations

• In-Circuit Serial Programming

• Low-Voltage In-Circuit Serial Programming

• In-Circuit Debugger

PIC16F87XA devices have a Watchdog Timer which can be shut-off only

through configuration bits. It runs off its own RC oscillator for added

reliability.

There are two timers that offer necessary delays on power-up. One is the

Oscillator Start-up Timer (OST), intended to keep the chip in Reset until the

crystal oscillator is stable. The other is the Power-up Timer (PWRT), which

provides a fixed delay of 72 ms (nominal) on power-up only. It is designed

to keep the part in Reset while the power supply stabilizes. With these two

timers on-chip, most applications need no external Reset circuitry

Sleep mode is designed to offer a very low current power-down mode. The

user can wake-up from Sleep through external Reset, Watchdog Timer

wake-up or through an interrupt.

Several oscillator options are also made available to allow the part to fit the

application. The RC oscillator option saves system cost while the LP crystal

option saves power. A set of configuration bits is used to select various

options.

MEMORY ORGANIZATION

There are three memory blocks in each of the PIC16F87XA devices. The

program memory and data memory have separate buses so that concurrent

access can occur and is detailed in this section.

The PIC16F87XA devices have a 13-bit program counter capable of

addressing an 8K word x 14 bit program memory space. The

PIC16F876A/877A devices have 8K words x 14 bits of Flash program

Memory.

PROGRAM MEMORY

Data Memory Organization

The data memory is partitioned into multiple banks which contain the

General Purpose Registers and the Special Function Registers. Bits RP1

(Status<6>) and RP0 (Status<5>) are the bank select bits.

Each bank extends up to 7Fh (128 bytes). The lower locations of each bank

are reserved for the Special Function Registers. Above the Special Function

Registersare General Purpose Registers, implemented as static RAM. All

implemented banks contain Special Function Registers. Some frequently

used Special Function Registers from one bank may be mirrored in

another bank for code reduction and quicker access.

Simple steps to Program PIC16F877A

First assemble the PIC16F877A circuit with the 5V power supply, 20MHz

crystal oscillator and two 22pF capacitors. If you only have 12 volt power

supply adapter, you need a 5V voltage regulator circuit. You can build 5V

voltage regulator circuit using 7805 IC, IN4007 diode and two 10uF

capacitors.

Download and install free C compiler for PIC16F877A from Microchip

which is free. Copy the C program example to blink LED. Compile the

program using CCS C compiler. The hex file for this program will be

created after success compiling. This hex file needs to be loaded into the

PIC16F877A.

What is MPLAB?

MPLAB is free software that is needed to burn hex file into PIC16F877A

program memory. Download MPLAB IDE from Microchip which is free.

Install and run it. Connect PICStartPlus programmer using rs232 cable with

you PC. Position the PIC16F877A chip onto the PICStartPlus programmer.

Follow MPLAB instruction to burn the hex file into PIC16F877A chip.

Once complete, remove PIC16F877A from PICStartPlus and insert it onto

the development board. Turn ON the 5V power supply and see what happen.

Two more component needed are LED and resistor.

What is PICStartPlus?

PICStartPlus is a hardware pragrammer that is used to burn hex file into

PIC16F877A. PICStartPlus consist of power supply socket and cable, rs232

cable that should be connected to PC and a 40 pin ZIF socket. PIC16F877A

chip should be placed onto the ZIF socket.