This document contains information about programming microcontrollers using C language including Keil and Proteus software. It provides examples of programs to generate square waves with varying frequency and duty cycle and sense analog signals using an ADC. The programs demonstrate using timers to create delays, interrupts for inputs, and reading analog sensor values to display on ports. The document discusses requirements for microcontroller applications and solutions for meeting needs like providing gate signals, sensing voltage, current, and speed.

1. Jay Pandit
12MT06PED016
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2. Contents
 Keil
 Proteus
 Some basic techniques for C programming
 Application 1
 Application 2
 Application 3
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3. 3

4. How to start 1st Keil project..
Install keil software from the installation file.
Start keil program from start menu or from desktop
shortcut.
4

5. Select New
μvision Project
5

6. Do not
change the
file type!!!
6

7. Atmel
7

8. AT89C51
8

9. Create
New File
9

10. Save file
as .c or
.asm
Right Click and select
Add files to group
Source 1
10

11. Click Add
11

12. 12

13. Select Options for
Target
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14. 14

15. 15
Any one want to try this ?????

16. Before we start programming
16
Data Types in Embedded C
Data Type Size in Bits Data range
Unsigned char 8-bit 0 to 255
(Signed) char 8-bit -128 to 127
Unsigned int 16-bit 0 to 65535
(Signed) int 16-bit -32768 to 32767
sbit 1-bit SFR bit Addressable
only
Bit 1-bit RAM bit-addressable
only
sfr 8-bit RAM addresses

17. Before we start programming
17
Interrupt numbers in C
Interrupt Name Number used by 8051
External interrupt 0 INT0 0
Timer interrupt 0 TF0 1
External interrupt 1 INT1 2
Timer interrupt 1 TF1 3
Serial communication RI+TI 4

18. 18
For loop
char i;
for(i=0;i<10;i++)
{
}
Write your
code here

19. 19
Infinite loop
while(1)
{
}
Write your
code here

20. Assembly instructions in C code
20
#pragma ASM
Write your
code here
#pragma END ASM

21. 21
Functions
int addition(int,int);
void main()
{
int i,j,k;
i = 10;
j = 10;
k = addition(i,j);
}
int addition(int a, int b)
{
int c
c = a + b;
return(c);
}

22. Requirements from microcontroller
Provide gate signals.
What are your expectations
from a microcontroller????
Variation in duty ratio of gate signals.
Variation in frequency of gate signals.
Sensing of voltage.
Sensing of current.
Sensing of speed.
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23. DC –DC Converter open loop
 Gate signals are in the form of square wave
 There may be change in duty ratio of gate
signals.
 There may be change in frequency of gate
signals.
23

24. Program 1
24
Problem statement :
Write a program to generate a square wave on pin 1 of port 2
Frequency of square wave = 1kHz
Duty ratio = 50%
Delay calculation :
Assume that XTAL = 11.0592 MHz .
 n = 500 μ /1.085μ = 460
 Count = 65536 – n = 65076
 Count in hex = FE34H
 Load TH = FEH and TL =34H

25. Program
25
#include <reg51.h>
sbit SW = P2^1;
void delay();
void main()
{
TMOD = 0x01;
while(1)
{
SW = 1;
delay();
SW = 0;
delay();
}
}
void delay()
{
TH0 = 0xFE;
TL0 = 0x34;
TR0 = 1;
while(!TF0)
;
TR0 = 0;
TF0 = 0;
}
Lets go to Keil for trying this program

26. Program 2
26
Problem statement :
Write a program to generate a square wave on pin 1 of port 2
Frequency of square wave = 10kHz
Duty ratio = variable.
Time period of wave = 100 μsec
We would be requiring two delays
 One for on time.
 Another for off time.

27. 27
Program
#include <reg51.h>
sbit SW P2^1
void delay1();
void delay2();
extern char count;
void main()
{
count = 0;
EA = 1;
EX0 = 1;
EX1 = 1;
IT0 = 1;
IT1 = 1;
TMOD = 0x01;
while(1)
{
SW = 1;
delay1();
SW = 0;
delay2;
}
}
void delay1()
{
TH0 = 0xFF;
TL0 = 210+count;
TR0 = 1;
while(!TF0)
;
TR0=0;
TF0=0;
}

28. 28
Program cont.
void delay2()
{
TH0 = 0xFF;
TL0 = 210-count;
TR0 = 1;
while(!TF0)
;
TR0=0;
TF0=0;
}
void external0() interrupt 0
{
count++;
}
void external0() interrupt 1
{
count--;
}
Lets try to simulate this program

29. Program 3
29
Problem statement :
Write a program to generate a square wave on pin 1 of port 2
Frequency of square wave = Variable.
Duty ratio = 50%.
Time period of wave = variable
Hence,
Count to be loaded in timer register = variable
Requirements to be satisfied by the program
User should be able to vary the frequency.
Frequency raise and lower commands are given by user.
There should be upper and lower limit on frequency.

30. 30
Solutions
• Delay can be created using - Timers
• User interface can be created by using - Interrupts
How to satisfy these
requirements using
program????
• Limits can be put by using conditions like if-else

31. Program
31
#include <reg51.h>
sbit SW = P2^1
void delay();
extern unsigned char count;
void main()
{
count = 0x01;
EA = 1;
EX0 = 1;
IT0 = 1;
IT1 = 1;
TMOD = 0x01;
while(1)
{
SW = 1;
delay();
SW = 0;
delay();
}
}
void delay()
{
TH0 = 0xFF;
TL0 = count;
while(!TF0);
TR0 = 0;
TF0 = 0;
}

32. 32
Program cont.
void external0() interrupt 0
{
if(count < 0xFA)
count++;
else
count = 0xFA;
}
void external0() interrupt 1
{
if(count > 0x01)
count--;
else
count = 0x01;
}

33. Requirements from microcontroller
Provide gate signals.
Variation in duty ratio of gate signals.
Variation in frequency of gate signals.
Sensing of voltage.
Sensing of current.
Sensing of speed.
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34. 34
How to sense analog signals like voltage, current???
Solution : Analog to digital converters.
Limitations of ADC:
It can read only positive voltage.
It can read voltage between 0-5V.
ADC can not read current.
Solution :
Current sensor produces proportional voltage output for
input current.
Voltage divider is used for sensing high voltage.
Tachometer generates voltage signal proportional to speed
Signal conditioning is required to sense negative voltages.

35. 35
ADC0804 chip
ADC0804 is an 8-bit parallel ADC.
It works with +5V voltage supply.
It has a resolution of 8 bits.
Conversion time depends on clocking signals applied to
CLK IN pin, but it cannot be faster than 110μs.

36. 36
Pin details of ADC0804
CS Chip select is an active low input used to activate chip.
RD Used to read the converted data. Signal should be active low
WR Start of conversion. Signal should be active low.
CLK IN Input for clock
INTR End of conversion
Vcc Supply voltage +5V
Vref/2 Kept open for reading voltage in range 0-5V.
D0-D7 Digital data output pins.

37. 37
Relation of Vref/2 and Vin range
Vref/2(V) Vin(V) Step size(mV)
Not connected 0 to 5 19.53
2.0 0 to 4 15.62
1.5 0 to 3 11.71
1.28 0 to 2.56 10
Step size = Vin(max)/256

38. 38
How to calculate output
Dout = Digital data output in decimal.
Vin = analog input voltage.
Dout = Vin/step size

39. 39
Program 4
Problem statement: Using the ADC and current sensor
read the value of current flowing in the branch of circuit,
and display it on port3
Solution:
Current sensor ACS712ELCTR-20A-T is used.
Current sensor can read current up to +/- 20A.
Gain of current sensor (refer data sheet).
ADC0804 is used.
Internal clock is used.

40. 40
Program
#include<reg51.h>
sbit READ = P2^5;
sbitWRITE = P2^6;
sbit INTR = P2^7;
void main()
{
unsigned char value;
P1 = 0xFF;
INTR = 1;
READ = 1;
WRITE = 1;
while(1)
{
WRITE = 0;
WRITE = 1;
while(INTR);
READ = 0;
value = P1;
READ = 1;
P3 = value;
}
}
Lets simulate this code.

41. Our achievements
Provide gate signals.
Variation in duty ratio of gate signals.
Variation in frequency of gate signals.
Sensing of voltage.
Sensing of current.
Sensing of speed.
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