Timers in 8051 microcontroller and their programming. There are 21 special function registers sfr in 8051 micro controller and this includes register a, register b, processor status word psw, pcon etc etc. The 8051 microcontroller special function registers are used to program and control different hardware peripherals like timers, serial port, io ports etc. Dec 08, 2012 8051 timers counters jose borges,patricio lima, marcos brito, marek mastylo, jakub nyk group 4 deec mpi slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. The pcon or power control register, as the name suggests is used to control the 8051 microcontrollers power modes. This can cause some problems in case batteries are used for power supply. The serial port of 8051 microcontroller supports full duplex communication i. Timer 2 is a 16bit timercounter installed only in new versions of the 8051 families. Dec 31, 2018 in this section, we will see different addressing modes of the 8051 microcontrollers.
Cpu registers provide explanations to the following register types. Two registers tmod and tcon are closely connected to this timer and control its operation. Each register is 16 bit register divide into lower and higher byte register as shown below. Timer mode control register tmod of 80518031 microcontroller the tmod register is used to select the operating mode and the timercounter operation of the timers. Timercounter special function registerstcon tr0 and tr1 are set by user to turn on. Timers of 89c51 microcontroller microcontroller projects. In this article, we focus on timerscounters of the 8051 micro controller. Reset initializes the stack pointer to location 07h, and it is incremented once to start from location 08h, which is the first register r0 of the second register bank. Multiple choice questions and answers on microcontrollers and. In fact, by manipulating the 8051 microcontroller special function registers sfrs, you can assess or change the operating mode of the 8051 microcontroller.
How to connect two routers on one home network using a lan cable stock router netgeartplink duration. In the indirect addressing mode, a register is used to hold the effective address of the operand. Jun 26, 2018 each 16bit timercounter is divided into 2, 8bit registers th1tl1 and th0tl0. Tmod and tcon registers are used for setting and using these timerscounters. Multiple choice questions and answers on microcontrollers and applicationspart1.
The 8051 has two counterstimers which can be used either as timer to generate a time delay or as counter to count events happening outside the microcontroller. Cleared when processor vectors to execute interrupt service routine located at program address 001bh. How to use internal timer registers of 805189c51,89c52. Tmod timer mode register and tcon timer control register, which are used for activating and configuring timers and counters. These two registers th and tl are timer high byte and timer low byte, 0 and 1 are the timers numbers. Each interrupt can be enabled or disabled by setting bits of the ie register. It is a subroutine calls that given by the microcontroller when some other program with high priority is request for acquiring the system buses than interrupt occur in. 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. Tcon timer control register with its individual bits and sfr. It then passes the control to the main program where it had left off. Registers of 80518031 microcontroller timer control register tcon. Two of them, th2 and tl2, are connected serially in order to form a larger 16bit timer register.
Registers of 80518031 microcontroller a media to get all. Interrupts are the events that temporarily suspend the main program, pass the control to the external sources and execute their task. The b register is only used by two 8051 instructions. Pcon register and power saving modes in 8051 generally speaking, the microcontroller is inactive for the most part and just waits for some external signal in order to takes its role in a show. There are 21 unique locations for these 21 special function. Thus, in order to use more than one register bank, the sp should be initialized to a different location. Dec 08, 2016 multiple choice questions and answers on microcontrollers and applicationspart1.
In 8051 there are 1byte, 2byte instructions and very few 3byte instructions are present. Cse 477 8051 overview 40 external interrupts can interrupt using the int0 or int1 pins port 3. Pcon is used to double the effective baud rate of the 8051s serial port. So you may have guessed something from the name itself special function registers known with an acronym sfr. There are 2 registers associated with 8051 timers which are timer control register and timer mode register. Serial port control and status register is the special function register scon. How is timercounter control register intel 8051 microcontroller register abbreviated. Atmel 8051 microcontrollers hardware manual 12 4316e80510107 table 11. Know about types of registers in 8051 microcontroller.
The counters and timers in 8051 microcontrollers contain two special function registers. It is an 8 bit register and each bit has a special function. Dec 20, 2016 how to connect two routers on one home network using a lan cable stock router netgeartplink duration. The tcon register consists of timer overflow flags, timer run control bits, external interrupt flags and external interrupt type control bits.
As the opcodes are 8bit data, there are 256 possibilities. Serial port control register scon of 8051 8031 microcontroller the format of scon register is shown. The psw register contains program status information as detailed in table. Apr 20, 2019 these two registers th and tl are timer high byte and timer low byte, 0 and 1 are the timers numbers. Tmod is an 8bit register used for selecting timer or counter and mode of timers. The 80518052 microcontroller architecture, assembly language, and hardware interfacing craig steiner universal publishers boca raton, florida.
This is an 8bit register which is used by both timers. For timer 0, the flag is bit 5, tf0, in the timercounter control register tcon. Registers in 8051 math register indicates that each bit a of the register can be programmed. 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 timer1. Objective questions and answers on microcontrollers and applications. Then timer 0 will use tr1 timer1 register and tf1 timer1 flag i. Lower 4bits are used for control operation of timer. In addition to the cpu registers r0 r7, all x51 variants have an sfr space that is used to address onchip peripherals and io ports. Microcontroller timers counters tmod tcon microcontroller. These registers hold the count values which are incremented during each machine cycle. Microcontroller timers counters tmod tcon microcontroller tutorial. The second special function register is timer control register. In this chapter, we will cover the details about the register configuration for the external interrupt in 8051 controllers.
Tcon and tmod timer registers of 8051 microcontroller. Special function registers ip, ie, tmod, tcon, scon, and pcon contain control. Multiple choice questions and answers on microcontrollers. This register contain not only the mode selection bits but also the 9th data bit for transmit and receive tb8 and rb8 and the serial part interrupt bits ti and ri scon serial port control register smo serial port mode 0 shift register. Internal memory instruction register acc accumulator b temporary register instruction decoder control logic c ac f0 rs1 rs2 ov p psw flags control lines rd wr psen ale etc. An interrupt is a signal to the processor emitted by hardware or software indicating an event that needs immediate attention. Figure 53 bits of the psw paiders arabu laiki latvija 2002 pdf register. How to use 8051 timer mode0,mode1,mode2,mode3 in tamil. This register, which holds the address, is called the pointer register and is said to point to the operand. Tcon is defined as timercounter control register intel 8051 microcontroller register somewhat frequently. Bits, symbols and functions of every bits of tcon register are as follows. Tcon is another register used to control operations of counter and timers in microcontrollers.
Internal operation of the 8051 timer same for both timers timer registers tcon timer control tmod timer mode th0tl0 timer 0 16 bit register byte addressable only th1tl1 timer 1 16 bit register byte addressable only tcon tcon sfr and its individual bits it0it1. I said 8051 is a 8bit controller and both timers are 16bit timer. Tcon stands for timercounter control register intel 8051 microcontroller register. Operating mode selection register and tcon timercounter operation control register, higher and lower order bytes of individual timercounters. Only registers r0, r1 and dptr can be used as pointer registers. Oct 09, 2018 pcon register and power saving modes in 8051 46. Tmod timer mode register and tcon timer control register, which are used for activating and configuring timers and counters timer mode control tmod. In the case of timers, register is incremented once every machine cycle. Unlike timers t0 and t1, this timer consists of 4 registers. Nov 30, 2017 the 8051 microcontroller special function registers are used to program and control different hardware peripherals like timers, serial port, io ports etc. Shift registers are a type of sequential logic circuits that are mainly used for the storage of digital. Tmod timer mode register and tcon timer control register, which are.
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