PIC introduction

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:

 

Controller No. of PINS Clock speed No. of instructions Program Memory EEPROM RAM Others
16C61 18 (13 I/O pins) 20 MHz 35 1Kx 14-bits  x 36 Bytes PoR, PWRT, WDT with onChip Osc, SLEEP mode, 3 Timers, CCP, Synchronous Serial Port (SSP) with SPI  and I2C, USART, Parallel slave port(PSP), BoR, 3 interrupt sources. 02 i/o ports
16F877 28/40 pins 20MHz 35 8Kx14-bits 256×8 bytes 368×8 bytes All above; 05 i/o ports, 14 interrupt sources

 

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:

PIN Signal Classification Signal name Description
1 MCLR’/Vpp Master Clear /

Programming voltage input.

The low signal on pin 1 resets this device
12,31,

 

Power Vss

 

Connected to Ground for all logic and i/o
11,32 Power Vdd Connected to Positive supply for all logic and i/o
2 Port A;       PORTA is a bi-directional I/O port RA0 I/O as well Analog i/p0
3 RA1 I/O as well Analog i/p1
4 RA2 I/O as well Analog i/p2 or –Ve analog reference voltage
5 RA3 I/O as well Analog i/p2 or +Ve analog reference voltage
6 RA4 RA4 can also be the clock input to the Timer0 timer/ counter. Output is open drain type
7 RA5 RA5 can also be analog input4 or the slave select for the synchronous serial port.
33 Port B ;Bi-directional i/o port. It can be software programmed for internal weak pull-up on all inputs RB0 / INT I/O as well as external INT input
34 RB1 I/O
35 RB2 I/O
36 RB3 / PGM I/O and can also be the low voltage programming input.
37 RB4 Interrupt-on-change pin
38 RB5 Interrupt-on-change pin
39 RB6/ PGC Interrupt-on-change pin or In-Circuit Debugger pin. Serial programming clock.
40 RB7 / PGD Interrupt-on-change pin or In-Circuit Debugger pin. Serial programming data
15

 

Bi-directional  Port C RC0/T1OSO/ T1CKI RC0 can also be the Timer1 oscillator output or a Timer1 clock input.
16 RC1/T1OSI/ CCP2 RC1 can also be the Timer1 oscillator input or Capture2 input/Compare2 output/PWM2 output.
17 RC2/CCP1 RC2 can also be the Capture1 input/Compare1 output/PWM1 output
18 RC3/SCK/SCL RC3 can also be the synchronous serial clock input/ output for both SPI and I2C modes
23 RC4/SDI/SDA RC4 can also be the SPI Data In (SPI mode) or data I/O (I2C mode).
24 RC5/SDO RC5 can also be the SPI Data Out (SPI mode).
25 RC6/TX/CK RC6 can also be the USART Asynchronous Transmit or Synchronous Clock.
26 RC7/RX/DT RC7 can also be the USART Asynchronous Receive or Synchronous Data
19

 

Port D ;            It is It is Bi-directional I/O and parallel salve port RD0/PSP0 PORTD is a bi-directional I/O port or parallel slave port when interfacing to a microprocessor bus.
20 RD1/PSP1
21 RD2/PSP2
22 RD3/PSP3
27 RD4/PSP4
28 RD5/PSP5
29 RD6/PSP6
30 RD7/PSP7
8 Bi-directional Port E RE0/RD’/AN5 RE0 can also be read control for the parallel slave port, or analog input5.
9 RE1/WR’/AN6 RE1 can also be write control for the parallel slave port, or analog input6
10 RE2/CS’/AN7 RE2 can also be select control for the parallel slave port, or analog input7
13 OSC1/ClkIn Oscillator and Clock Oscillator crystal input/external clock input

 

14 OSC2/ClkOut Oscillator and Clock Oscillator crystal output. Connects to crystal or resonator in crystal oscillator mode. In RC mode, OSC2 pin outputs CLKOUT which has 1/4 the frequency of OSC1, and denotes the instruction cycle rate.

 

Updated: September 2, 2020 — 2:17 pm

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