The pcon or power control register, as the name suggests is used to control the 8051 microcontrollers power modes. Objective questions and answers on microcontrollers and applications. The normal priority of these interrupts from highest to lowest are external interrupt 0, timer0. The final word on the 8051 page 1introductionthis is a book about the intel 8051 microcontroller and its large family of descendants. Atmel 8051 microcontrollers hardware 1 0509c 8051 0706 section 1 8051 microcontroller instruction set for interrupt response time information, refer to the hardware description chapter. Multiple choice questions and answers on microcontrollers. Scon register the first two bits are sm0, sm1 which is the serial port mode bits. It is used to hold data which is to be transferred serially. These timers and counters are used as interrupts in 8051 microcontroller.
Most popular in the 1980s and early 1990s, today superseded by enhanced devices with 8051. Scon serial control register microprocessor and microcontroller. There are two 16bit timers and counters in 8051 microcontroller. The sfrs associated with serial port are scon serial data communication control register, pcon power mode control register, sbuf serial buffer, combination of transmit buffer and receive buffer interrupt. We can use microcontrollers to interact with gsm module and lcd to get the response from gsm module. If ea 0, then it disable all the five interrupts of 8051. The timers are controlled using tmod, the timer mode register, and tcon, the timer control register. When high or 1 it allows 8051 to receive data from rxd pin.
Serial port control and status register is the special function register scon. So you may have guessed something from the name itself special function registers known with an acronym sfr. General purpose registers in 8051 all about circuits. But when comes to a microcontroller, we cannot afford to dedicate many pins for data transfer. Timercounter in 8051 8051 has two 16bit timercounter registers.
Transmit interrupt this is a flag bit when 8051 finish the transfer of the 8bit character, it raises the ti flag to indicate that it is ready to transfer another byte. Receive bit 8 is used for serial modes 2 and 3, so here we make rb80. Both timers consist of 16bit register in which the lower byte is stored in tl and the higher byte is stored in th. Tcon and tmod timer registers of 8051 microcontroller.
It is an 8 bit register used to program start bit, stop bit, and data bits of data framing, among other things. For a byte orthosis pdf of data to be transferred via e one of the alternate register banks i. How is power control intel 8051 microcontroller register abbreviated. During reception the stop bit is stored as rb8 in scon register. If you observe in internal ram structure, the address space from 80h to ffh is allocated to sfrs. Pcon is defined as power control intel 8051 microcontroller register very frequently. Scon is a bit addressable register containing status. It is used to specify framing format, how to calculate baud. These registers can be accesse d like any other register, such as a,b, r0, r1, r2 etc. Uart or serial communication in 8051 microcontroller will allow the controller to.
Universal asynchronous reveiver and transmitter block diagram is shown in figure. In our examples the baud clocks are, in fact, a single clock. The stack in 8051 family must reside in the internal memory. Pcon stands for power control intel 8051 microcontroller register. The stack grows upwards using preincrement and post decrement for the stack pointer. Its very easy to interface gsm with 8051, we just need to send at commands from microcontroller and receive response from gsm and display it on lcd. Symbol name address resetvalue acc accumulator e0 0000 0000 00 b b register f0 0000 0000 00 psw program status word d0 0000 0000 00 sp stack pointer 81 0000 0111 07 dpl low byte dptr 82 0000 0000 00 dph high byte dptr 83 0000 0000 00.
The scon bits are defined as sm0, sm1, sm2, ren, tb8, rb8, ti, ri from msb to lsb. Each interrupt can be enabled or disabled by setting bits of the ie register and the whole interrupt system can be disabled by clearing the ea bit of the same register. These two registers th and tl are timer high byte and timer low byte, 0 and 1 are the timers numbers. Tmod and tcon registers are used for setting and using these timerscounters. Serial communication in 8051 microcontroller gadgetronicx. 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. Keil is a german based software development company. Cpu registers provide explanations to the following register types. Project report on microcontroller embedded system 1. Flags ri and ti are parts of a bit addressable register scon, which resides at address 98h in the special function register area. There are 21 unique locations for these 21 special function registers and each of these register is of 1 byte size. 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. In the 8051, register a, b, dptr, and psw are a part of the group of registers commonly referred to as sfr special function registers. Mckinlay contents introduction to computing the 8051 microcontrollers 8051 assembly language programming branch instructions io port programming 8051 addressing modes.
Interfacing serial port rs232 with 8051 microcontroller 1. Pcon power control intel 8051 microcontroller register. Hardware smbustm i2ctm compatible, spitm, and uart. The microcontroller has built in rom, ram, input output ports, serial port, timers, interrupts and clock circuit. All books are in clear copy here, and all files are secure so dont worry about it.
Also it is used to control transmit and receive operations. 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. So we are going to interface gsm with a 8051 microcontroller at89s52. The low byte register is called tl0 timer 0 low byte and the high byte register is referred to as th0 timer 0 high byte.
This site is like a library, you could find million book here by using search box in the header. Read online serial port control register scon of 8051 8031. Serial port control register scon of 8051 8031 microcontroller the format of scon register is shown. The 16bit register of time 0 is accesses as low byte and high byte. Pcon register in 8051 pdf pcon register in 8051 pdf pcon register in 8051 pdf download. So, if you follow this formula then you can get the delays and whenever any instruction uses sbuf as its destination register transmission will start. Microcontroller serial communication scon,sbuf microcontroller. The sfr area includes the cpu registers sp stack pointer, psw program status word, a accumulator, accessed via the sfr space as.
The interrupts are recognized by the controller only if they are enabled. Both can be configured to operate either as timers or as event counters. Uart universal asynchronous receiver and transmitter. The format of ie register is, if ea 0, then it disable all the five interrupts of 8051. Serial control register scon is used to set serial communication operation modes. A register is a storage element that can be store bits of information, a register file is a collection of registers, which are the same length. Concept of serial communication in 8051 microcontroller.
The b0, b1, b2, and b3 stand for banks and each bank contains eight general purpose registers ranging from r0 to r7. Operations on sfr byte address 208 or bit addresses 209215 that is, the psw or bits in the psw also affect flag setti ngs. If the program size is more than 4 k bytes 8051 will fetch the code automatically from external memory. 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. The 8051 microcontroller and embedded systems using assembly and c second edition muhammad ali mazidi janice gillispie mazidi rolin d.
A microcontroller is an entire computer manufactured on a single chip. One of the 8051 s many powerful features integrated uart, known as a serial port to easily read and write values to the serial port instead of turning on and off one of the io lines in rapid succession to properly clock out each individual bit, including start bits, stop bits and parity bits. The 8051 contains two registers, one for receiving and the other for sending serial data. The 8051, being a communicationsoriented microcontroller, gives the user the ability to. There are 21 unique locations for these 21 special function. Microcontrollers notes for iv sem ecetce students saneesh. It provides several development tools like ide integrated development environment project manager simulator debugger c cross compiler, cross assembler, locatorlinker keil software provides you with software development tools for the 8051 family of microcontrollers. The higher order 8bit address is taken the address available in the p2 sfsr and the lower order 8bit address is the data available in register ro. Gsm module interfacing with 8051 microcontroller at89s52. Thus, in order to use more than one register bank, the sp should be initialized to. Accumulator is an 8 bit register widely used for all arithmetic and logical operations. When the 8051 is first booted up, register bank 0 addresses 00h through 07h is used by default.
Multiple choice questions and answers on microcontrollers and applicationspart1. The whole process is in control of the bits of the scon register serial control. The port is a receive buffered, due to this port can start receiving byte before the previous bytes has already been read from the register sbuf. The 80518052 microcontroller architecture, assembly language, and hardware interfacing craig steiner universal publishers boca raton, florida. The basic architectural structure of this 8051 core is. Special function registers ip, ie, tmod, tcon, scon, and pcon contain control and status bits for the interrupt system, the timercounters, and the serial port. It is intended to give you, the reader, some new techniques for optimizing your 8051 projects and the development. The ie register is used to enabledisable the interrupts of 8051. It is a fullduplex port, thus being able to transmit and receive data simultaneously.
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