8051 microcontroller timer and counter pdf

Timer counter in 8051 8051 has two 16bit timer counter registers. Recall 8051 timer counter can count up to 65535 and 16 bits cover 65535 in binary. In this article, we focus on timers counters of the 8051 micro controller. Since 8051 89c51,89c52 is an 8bit microcontroller, so to load 65535 we need two registers one representing the high byte and other the low byte. Among all the microcontrollers in use today, the 8051 and its variations are considered the most popular. In this lecture we will study timer and use of timer in 8051 microcontroller. Muhammad ali mazidi is the finest writer of all time for writing technical books like pic, 8051 and other technologies worldwide, the 8051 microcontroller and embedded systems 2nd ed muhammad ali mazidi is the comprehensive book based on 8051 microconrollers and its variant like 89c51, 89c52, 89s51, 89s52 and other variants. Both timers consist of 16bit register in which the lower byte is stored in tl and the higher byte is stored in th. The timer or counter mode is selected by control bits ct in the special function register tmod. Types of timer in 8051 microcontroller and timer and counter programming. The t89c51ac2 is an 8bit microcontroller based on the 8051 architecture. The 8051 can be set up so that an interrupt occurs whenever tf1 or tf0 is set.

When their count rolls over from the maximum count to 0000, they set the corresponding timer. When power is reconnected, it displays the real time irrespective to the time and duration it was in off state. Mckinlay contents introduction to computing the 8051 microcontrollers 8051 assembly language programming branch instructions io port programming 8051 addressing modes arithmetic. Included in the programmable counter array are a 16 bit free running timer and 5 separate modules. Timer counter internal rom io ports interrupt circuits clock circuits. It was referred as system on a chip because it had 128 bytes of ram, 4k byte of onchip rom, two timers, one serial port, and 4 ports 8bit wide, all on a.

Let us see the major components of 8051 microcontroller and their functions. These timers and counters in 8051 microcontroller are present in both the 8051 and the 8052. Each register is 16 bit register divide into lower and higher byte register as shown below. The timer is equipped with four 7segment displays that will count from 00.

The format of tmod register is, the lower four bits of tmod register is used to control timer 0 and the upper four bits are used to control timer 1. Timer can be used as a counter as well as for timing operation that depends on the source of clock pulses to counters. In this manual we will study about the 8051 architecture, its features, programming and interfacing. When used as counters, they increment at a rising edge signal from an external pin. The 80518052 microcontroller architecture, assembly language, and hardware interfacing craig steiner universal publishers boca raton, florida. The 8051 microcontroller kenneth j ayala 3rd edition. Problem statement in this lab, we will use the popular 8bit 8051 microcontroller to design a system to perform time count. Since the 8051 has an 8bit architecture, each 16bit is. In timing operation, both timers increment at onetwelfth of the oscillator frequency. When using the timer counter as a timer the registers thx and tlx increments for every machine cycle that is it obtains clock source from crystal which is connected to xtal1 and xtal2 pins of the microcontroller. Microcontroller at89c51 based countdown timer project. In the case of timers, register is incremented once every machine cycle.

What is difference between timer and counter in 8051. Setting the mode bits to l0b in tmod configures the timer to use only the tlx counter as an 8bit counter. Various features of 8051 microcontroller are given as follows. Project engineer 22 80511 a seven segment display is the most basic electronic display device that can display digits from switch 3 s 3. These counters are again divided into a 8 bit register. Before learning about 8051 timer programming, you should know how to use keil for 8051 programming and how to use input put ports of 8051 microcontroller. These timers can either be configured as timers to generate a time delay or as counters to count events occurring outside the microcontroller. Timer 2 is a 16bit timer counter installed only in new versions of the 8051 families. The 8051 has two counters timers which can be used either as timer to generate a time delay or as counter to count events happening outside the microcontroller.

Each counter has a 16 bit count register in the sfr area. Main the 8051 microcontroller and embedded systems using assembly and c. You may consider following approach to update all the variables properly at every millisecond tick. Seven segment digital clock with time set using microcontroller digital clocks. How to use internal timer registers of 805189c51,89c52. Timer mode control register tmod of 8051 8031 microcontroller the tmod register is used to select the operating mode and the timer counter operation of the timers. An 8051 microcontroller has the following 12 major components. Real time clock means it runs even after power failure. In this project we have used a 16x2 lcd module to display the. The 8051 microcontroller and embedded systems using. Mcs 8051 is an 8bit single chip microcontroller with many builtin functions and is the core for all mcs51 devices. The 8051 is an 8bit processor the cpu can work on only 8 bits of data at a time 8051 microcontroller. Thx is used to hold a value that is loaded into tlx every time tlx overflows from ffh to 00h.

The first microprocessor 4004 was invented by intel corporation. Digital clock using 8051 microcontroller with rtc ds7. Whenever its input pulses, the 8051 decrements the counter value. Countdown timer using microcontroller at89c tue dec 18 tuesday, january 1, there is a buzzer added to indicate timer has expired. In the timer function, the register is incremented every machine cycle. Timer counter special function registerstmod m0 and m1 bits are used to set timer mode the same for timer0 and timer1 8051 delivers 4 timer modes. The pins from 10 to 17 are for port3 which is a special port, and it is multifunctional.

Whereas counters require external clock source to be fed into the t0 p3. The timers are used for measurement of intervals to determine the pulse width of pulses. There are many versions of microcontrollers 8051, 80528751, at8951 from atmel corporation and many more. Jay makawana 151290109027 pratik bhatt 151290109005 shaktisinh gohil 151290109014 dhruv pandya 151290109032 department of electrical engineering subject. There are two 16bit timers and counters in 8051 microcontroller.

Major components of intel 8051 microcontroller the 8051 microcontroller is an 8bit microcontroller. Embedded systems 8051 microcontroller tutorialspoint. Unlike timers t0 and t1, this timer consists of 4 registers. Timers and counters in 8051 microcontroller and its. Two of them, th2 and tl2, are connected serially in order to form a larger 16bit timer register. These two timers and counters in 8051 microcontroller have four operating modes, which are selected by bitpairs ml, m0 in tmod. Each timer consists of two 8bit registers, tln and thn. Both can be configured to operate either as timers or as event counters. For interrupt response time information, refer to the hardware description chapter. Tmod and tcon registers are used for setting and using these timers counters.

Since the 8051 follows an 8bit architecture, each 16 bit is accessed as two separate registers of lowbyte and highbyte. The 8051 microcontroller and embedded pdf free download. M1 m0 mode description 0 0 mode 0 bit timer 0 1 mode 1 16bit timer 1 0 mode 2 8bit auto reload 1 1 mode 3 split timer mode april 10 9. Inside the 8051 microcontroller block diagram timers counters. The 9th pin rst is used for restarting the 8051 microcontroller. The low and high bytes can be accessed as separate bytes. Timers and counters in 8051 microcontroller baud rate. In 1981, intel introduced an 8bit microcontroller called the 8051.