Miicrocontroller Ece-Assignment 3

8/4/2019 Miicrocontroller Ece-Assignment 3

1/7

Homework Title / No. : _____3____________Course Code : ___ECE310______

Course Instructor : __Ms. Ritu__________ Course Tutor (if applicable) : ____________

Date of Allotment : ____________________ Date of submission : _______23/04/ 2010

Students Roll No. ____RH6802B54_____Section No. : _______H6802_____________

Declaration:I declare that this assignment is my individual work. I have not copied from any

other students work or from any other source except where due acknowledgment

is made explicitly in the text, nor has any part been written for me by another

person.

Students Signature : Ramjee

prasad

Evaluators comments:

_____________________________________________________________________

Marks obtained : ___________ out of _____________________

Content of Homework should start from this page only:

PART-A

1. Write a program to transfer 50 bytes placed at 0300H onwards and save

them to 20H onwards

Sol: Org 0h

Back : Mov dptr, #0300h

Mov r0, #50h

Mov r1, #20h

Mov a, @a+dptr

Mov @r1, a

Inc r1

Inc dptr

Djnz r0, Back

end

2. How can we send and receive data serially with 8051? How can we change

the baud rate?


2/7

Sol:-

One of the 8051s many powerful features is its integrated UART, otherwise

known as a serial port. The 8051 has an integrated serial port means that we

may very easily read and write values to the serial port. If it were not for the

integrated serial port, writing a byte to a serial line would be a rather tedious

process requiring turning on and off one of the I/O lines in rapid succession to

properly "clock out" each individual bit, including start bits, stop bits, and parity

bits.

The first things we must do when using the 8051s integrated serial port is,

obviously, configure it. This lets us tell the 8051 how many data bits we want,

the baud rate we will be using, and how the baud rate will be determined.

Bits SM0 and SM1 let us set the serial mode to a value between 0 and 3, inclusive.The four modes are defined in the chart immediately above. As you can see,selecting the Serial Mode selects the mode of operation (8-bit/9-bit, UART or ShiftRegister) and also determines how the baud rate will be calculated. In modes 0 and

2 the baud rate is fixed based on the oscillators frequency. In modes 1 and 3 thebaud rate is variable based on how often Timer 1 overflows. Well talk more aboutthe various Serial Modes in a moment.

The next bit, SM2, is a flag for "Multiprocessor communication." Generally,whenever a byte has been received the 8051 will set the "RI" (Receive Interrupt)flag.

The next bit, REN, is "Receiver Enable." This bit is very straightforward: If you wantto receive data via the serial port, set this bit. You will almost always want to setthis bit.

The last four bits (bits 0 through 3) are operational bits. They are used whenactually sending and receiving data--they are not used to configure the serial port.

The TB8 bit is used in modes 2 and 3. In modes 2 and 3, a total of nine data bits aretransmitted. The first 8 data bits are the 8 bits of the main value, and the ninth bit istaken from TB8. If TB8 is set and a value is written to the serial port, the datas bitswill be written to the serial line followed by a "set" ninth bit. If TB8 is clear the ninthbit will be "clear."


3/7

The RB8 also operates in modes 2 and 3 and functions essentially the same way asTB8, but on the reception side. .

TI means "Transmit Interrupt." When a program writes a value to the serial port, acertain amount of time will pass before the individual bits of the byte are "clockedout" the serial port.

Finally, the RI bit means "Receive Interrupt." It functions similarly to the "TI" bit, butit indicates that a byte has been received.

Setting the baud rate

Baud rate register value

9600 -3

4800 -6

2400 -12

1200 -24

In order to select a baud rate we have to feed its corresponding register value to

the register th1 in serial port programming. This is done in the 2nd step after timer

mode 2 is selected.

3. Write a program to generate a square wave on port 3.1 with on/off duty cycle

having 60/40 ratio. Assume crystal oscillator to be 12MHz.

Sol: - Org 0h

Loop :setb p3.1

Acall delay

Acall delay

Clr p3.1

Acall delay

Sjmp loop

PART-B

1. Write a program which will transfer a byte placed in register R4, serially on

TxD pin of 8051 with baud rate 9600 bps.


4/7

Sol:- Org 0h

Mov a,@r4

Mov tmod, #20h

Mov th1, #-3h

Mov scon,#50h

Setb tr1

Mov sbuf, a

Check : Jnb TI, check

end

2. Assume that eight LEDs are connected with port-1 and their anodes areconnected with ground. Write a program to ON the LED one by one at an

interval of 1 second. When all LED are ON, then switch OFF the LEDs in the

similar fashion.

Sol: - org 0000

mov p1, #11111111blcall delaymov p1, #01111111blcall delaymov p1, #001111111blcall delaymov p1, #00011111blcall delaymov p1, #00001111blcall delaymov p1, #00000111blcall delaymov p1, #00000011blcall delaymov p1, #00000001blcall delaymov p1, #00000000blcall delaymov p1, #00000001blcall delaymov p1, #00000011blcall delaymov p1, #00000111blcall delaymov p1, #00001111b


5/7

lcall delaymov p1, #00011111blcall delaymov p1, #00111111blcall delaymov p1, #01111111blcall delaymov p1, #11111111blcall delay

delay : mov r0, #05hking :mov r1, #0ffhback : mov r2, #0ffhloop :djnz r2, loopdjnz r1, backdjnz r0, kingret

end

3. Write a program to read from the 4X4 matrix keyboard and display thecharacter on the 7 segment connected to port 1 as shown in fig. below

Org 0000

Mov p2, #0ffh

K1 : Mov p1, #0

Mov a, p2

Anl a, #00001111b

Cjne a, #00001111b, k1

K2 : Acall delay

Mov a, p2

Anl a , #00001111b


6/7

Cjne a, #00001111b, over

Sjmp k2

Over : mov a, p2

Anl a, #00001111b

Cjne a, #00001111b, over 1

Sjmp k2

Over 1: mov p1, #11111110b

Mov a, p2

Anl a, #00001111b

Cjne a, #00001111b, row_0

Mov p1, #11111101b

mov a, p2

anl a, #00001111b

cjne a, #00001111b, row_1

mov p1, #11111011b

mov p2, a

anl a, #00001111b

cjne a, #00001111b, row_2

mov p1, #11110111b

anl a, #00001111b

cjne a, #00001111b, row_3

ljmp k2

row 0 : mov dptr, #kcode0

sjmp find

row 1: mov dptr, #kcode1

sjmp find

row 2: mov dptr, #kcode2

sjmp find


7/7

row 3 : mov dptr, #kcode3

sjmp find

find : rrc a

jnc match

inc dptr

sjmp find

match : clr a

movc a, @a+dptr

mov p0,a

ljmp k1

org 300h

kcode0 : DB 0,1,2,3

kcode1 : DB 4,5,6,7

kcode2 : DB 8,9,a,b

kcode3 : DB c, d, e, f

end

Documents

Miicrocontroller Ece-Assignment 3