03-Jun-11

This presentation contains illustrations from the book
‘Programming 8-bit PIC Microcontrollers in C’

Programming
8-bit PIC
Microcontrollers
in C
Martin Bates
Elsevier 2008

Part 1 Microcontroller Systems
describes in detail the internal architecture and interfaces
available in the PIC 16F887A, a typical PIC chip, as well as
outlining the main features of the development system
Part 2 C Programming Essentials
provides simple example programs for the microcontroller
which show the basic principles of C programming,
and interfacing to basic I/O devices
Part 3 C Peripheral Interfaces
provides example programs for operating PIC chips with a
full range of peripherals, using timers and interrupts

Figure 1.1

Part 1

MICROCONTROLLER
SYSTEMS


The microcontroller contains all these elements in one chip

Figure 1.2

16F877 pin-out

Figure 1.3

PIC 16F877 MCU Block diagram
Flash
ROM
Program
Memory
8192
x 14 bits

Program Counter
(13 bits)
Address
Stack
13 bits
x8
levels

0000 – 1FFF
Instructions

RAM
File
Registers

(8 bits)
EEPROM
256 bytes

MCU
control
lines

Ports, Timers
ADC, Serial I/O

Timing control
Clock

Reset
Port

A

B

C

D

E

The microcontroller pins have multiple functions
Shows the main parts of the chip in simplified form



000h

Indirect

080h

Indirect

100h

Indirect

180h

Indirect

001h

Timer0

081h

Option

101h

Timer0

181h


183h

Status Reg

004h

File Select

084h

File Select

104h

File Select

184h

File Select

005h

Port A data

085h

PortA direction

105h


107h

-

187h

-

008h

Port D data

088h

PortD direction

108h

-

188h

-

009h

Port E data

089h


Interrupt Control

10Bh

Interrupt Control

18Bh

Interrupt Control

00Ch
to
01Fh

20 Peripheral
Control
Registers

08Ch
to
09Fh

20 Peripheral
Control
Registers

020h
to
06Fh

4 Peripheral
Control
Registers
96 General
Purpose
Registers

18Ch
to
18Fh
190h
to
1EFh

4 Peripheral
Control
Registers
96 General
Purpose
Registers

170h
to
17Fh

Accesses
70h – 7Fh

1F0h
to


=6

8


Latch

Pins

10FXXX

12FXXX

16FXXX

Comment

Low pin count, small form factor,
cheap
No EEPROM, none low power,
assembler program
Low pin count, small form factor,
cheap
EEPROM, 10-bit ADC, some low
power, assembler
Mid-range, UART, I2C, SPI
many low power, C or assembler
program

-

I/O pin operation

Data
Direction

Binary Counter

Compare
register

Input
Data
Latch

Power range, 3V supply, no
EEPROM,
data RAM < 8 KB, C program

General Timer Operation
Capture
signal

Instruction
Clock

76 x 24
bits

High range, CAN, USB
J series 3V supply, C program

Post-scaler
(output
divide)



Reference volts, Vf

Vref+

Setup ADC
Read ADC

Vc-

Compartor
status bit
Vc+ > Vc-

8-bit or 16-bit
integer result

The comparator simply sets a bit if one input is higher than the other
The ADC converts an analog input into a binary code

2


03-Jun-11

Table 1.3
Figure 1.8

Parallel Slave Port operation



CCP2

Timer 2 capture or compare detected

INT_CCP2

TIMERS

Chip select
Read
Write

Interrupt
Parallel
Slave
Port

PORTS

EXTERNAL
Data x 8

INTERNAL
Data x 8

RB0/INT pin

Change on single pin RB0


UART Serial Port

Received data available

INT_RDA

UART Serial Port

Transmit data buffer empty

INT_TBE

SPI Serial Port

Data transfer completed (read or write)

INT_SSP

I2C Serial Port

Interface activity detected

INT_SSP

I2C Serial Port

Bus collision detected

INT_BUSCOL


Program Execution
3
Timeout
Interrupt

TX1 Transmit

4
Jump to
ISR

RX2

Line
Driver
Interface

RX1 Receive

7
Continue

+/- 12V
TX2
COM PORT
Ground

Ground
5
Time-out

1

Slave 1

0

Time
Idle

Start
Bit

Bit
0

Bit
1

Bit
2

Bit
3

Bit
4

Bit
5


SS3

SPI uses hardware slave selection and separate clock

3


03-Jun-11

Figure 1.13

+5V
7

SDO/SDI

6

5

4

3

2

I2C Connections

Figure 1.14



Figure 1.15

/*
OUTBYTE.C
Start
SDA

Acknowledge

Address / Data bits
7

6

5

4

3

2

1

0

MPB

#include "16F877A.h"

:1000100083161F149F141F159F1107309C00880121
:08002000FF3083128800630029
:02400E00733FFE
:00000001FF
;PIC16F877A

The machine code is downloaded as a binary file to the chip

The C program is compiled and tested in simulation mode

4


03-Jun-11

Figure 1.17

Figure 1.18

PICkit2 demo system hardware

ICSP target board connections
Application Board
Reset
10k

ICSP
Interface

MCU

+ C Compiler

ICD2 program and debug system

USB

ICD2
interface

6-WAY
connector

Figure 1.20

Microchip ICD2 module

ICD2 provides in-circuit debugging

Figure 1.22

ICD debugging windows

PIC MCU
Target
System

Block diagram of the ICD2 programming and in-circuit debugging system

User interface for in-circuit programming & debugging