Now coming towards interrupt, interrupt is interrupt :P Yeah really, we call it interrupt because its an interrupt. In programming codes there are many things which needs to run in background and appear when its time for them to appear. Here where interrupt comes handy. Interrupt is kind of a background code which keeps on running in the background while the main code keeps on running in front but when the interrupt condition is fullfilled then it interrupts the main program and executes the functions defined in it. For Timer interrupts, suppose I wanna blink my LED after every 2 seconds then what will I do is I will start a timer for 2 seconds and when this timer completes I will generate an interrupt. So, in this way after every two seconds the led will blink. So, let's start with timers interrupt in 8051 Microcontroller and see how we are gonna do this.
As I explained earlier, we are gonna use Timer interrupt in 8051 Microcontroller. so, now before gong into the details, let me first throw some light on how we are gonna implement this. Timers count from 0 to 255 in 8 bit mode as in 8 bit 255 is the maximum value and when timer hits the 255 number then we say that our timer is overflowed. Now when timer overflows, then it sends us a indication using which we generate our intterupt. In timers, there are few registers in which they store their value. If we are talking about Timer0 then timer0 stores its value in TL0 register. Now suppose I want my timer to start counting from 10 instead 0 then I will store 10 in my TL0 register and it will count from 10 instead 0 and when it reaches 255 it will overflow. Now when Timer0 will overflow then it will make TF0 bit HIGH. TF0 is another register value, if its 1 then it means that our timer is full and if its 0 then it means our timer is still counting. So, that's how we count from our timer and check the pin TF0. Now first of all, I am gonna use Timer0 and then we will have a quick look at Timer1.
#include<reg51.h>
// Out Pin
sbit Out = P2^0; // Pin P2.0 is named as Out
//Function declarations
void cct_init(void);
void InitTimer0(void);
int main(void)
{
cct_init(); // Make all ports zero
InitTimer0(); // Start Timer0
while(1) // Rest is done in Timer0 interrupt
{
}
}
void cct_init(void)
{
P0 = 0x00;
P1 = 0x00;
P2 = 0x00;
P3 = 0x00;
}
void InitTimer0(void)
{
TMOD &= 0xF0; // Clear 4bit field for timer0
TMOD |= 0x02; // Set timer0 in mode 2
TH0 = 0x05; // 250 usec reloading time
TL0 = 0x05; // First time value
ET0 = 1; // Enable Timer0 interrupts
EA = 1; // Global interrupt enable
TR0 = 1; // Start Timer 0
}
void Timer0_ISR (void) interrupt 1 // It is called after every 250usec
{
Out = ~Out; // Toggle Out pin
TF0 = 0; // Clear the interrupt flag
}
Download Timer0 Code and Simulation
#include<reg51.h>
// Out Pin
sbit Out = P2^0; // Pin P2.0 is named as Out
//Function declarations
void cct_init(void);
void InitTimer1(void);
int main(void)
{
cct_init(); // Make all ports zero
InitTimer1(); // Start Timer1
while(1) // Rest is done in Timer1 interrupt
{
}
}
void cct_init(void)
{
P0 = 0x00;
P1 = 0x00;
P2 = 0x00;
P3 = 0x00;
}
void InitTimer1(void)
{
TMOD &= 0x0F; // Clear 4bit field for timer1
TMOD |= 0x20; // Set timer1 in mode 2
TH1 = 0x05; // 250 usec reloading time
TL1 = 0x05; // First time value
ET1 = 1; // Enable Timer1 interrupts
EA = 1; // Global interrupt enable
TR1 = 1; // Start Timer 1
}
void Timer1_ISR (void) interrupt 3 // It is called after every 250usec
{
Out = ~Out; // Toggle Out pin
TF1 = 0; // Clear the interrupt flag
}
Download Timer1 Code and Simulation
That's all for today, I hope you guys have got something out of today's post and gonna like this one. In the coming post, I am gonna design some simple project on 8051 Microcontroller in which I will use these Timers, then you will get know more about them. So, stay tuned and subscribe us by email. Take care !!! :)
8051 Microcontroller, as we all know, is another Microcontroller series just like PIC Microcontroller or Arduino etc. The benefit of 8051 Microcontrollers is that they are quite cheap and easily available so if you are going to design some product then its better to use 8051 Microcontroller instead of PIC Microcontroller or Arduino etc. As they are cheap so they also come with a disadvantage which is that they are not much rich with features. Few of 8051 Microcontrollers doesn't even support Serial Communication. So, before choosing it for your project, must check their datasheet to confirm that they are suitable for your projects.
In most of these below projects, I have designed the complete simulation in Proteus and the code is also given but my suggestions is don't simply download the simulation and run it. Instead design the simulation from scratch and then design your code and run the simulation on your own. Consider my codes and simulations as a guide but dont get dependent on them as then you are not gonna get anything. Anyways let's get started with 8051 Microcontroller Projects.
Below are mentioned all the 8051 Microcontrollers Projects, which I have shared on this blog. You can check these projects and can also download their simulations designed in Proteus. I have given codes for most of these projects but few are paid, which you can buy from our shop at a quite minimal rate.
These are basic projects and are best for beginner level programmers. If you are new to 8051 Microcontroller then first read these projects. These all projects contain complete codes as well as the Proteus simulation so you can quite easily test them in Proteus software and can edit the codes and learn from it.
These are Intermediate level 8051 Microcontroller Projects. If you wanna do these projects then you must first learn or atleast have a look at basic 8051 Microcontroller projects as they are using same components as we interfaced in basic level. If you feel any problem then ask in comments.
That's all for today, but I am gonna add more projects in it and will keep on updating the list. Subscribe us and get these exciting tutorials straight to your mail box.