http://www.8051projects.net/ Learn to make simple microcontroller projects, pic, 8051, avr and arm projects. download 8051 projects, tutorials, libraries, sample codes. join the microcontroller discussion forum and ask doubts regarding electronics. the best source for 8051 over internet. en-gb 2009-01-08T12:17:17-08:00 contact@nospam.com hourly 1 2000-01-01T12:00+00:00 http://www.8051projects.net/forum-t9130.html 2009-01-08T12:17:17-08:00 actually i want to see the display through ports of the microcontroller by connecting a 7-segment display to it,how will i connect this 7-segment display to port1 of the mirocontroller(8051),i am designing the circuit on a breadboard,what will be the program code???please helpme,its too urgent/// http://www.8051projects.net/forum-t9130.html 2009-01-08T12:17:17-08:00 Arun Kumar V Hi,From i want understand from your posts- the ADC value is displayed in Binary format on 8 LEDs on a port ( 33H(hex) - 00110011 (binary) - led7. ........led0 (Display on port)1) you need a "Hex2BCD" conversion routine to display hex value into BCD on a 7 segment display For Eg: 33H is displayed as 51Decimal (BCD) on 2-digit 7seg display after conversion.2) if you just need the 2 digit 7 seg to display - 33, then instead of sending the processed ADC value to Port directly store it in some Register and make a look up table containing patterns for generating numbers from 0 to 9. i think this is where you are getting confused, i think you are aware of the segments in a 7 seg display - seg a,b,c,d,e,f,g,h (decimal point) - to construct 0(zero) on a 7 seg display you have to output the port with - 11000000b or #0C0H this will mean connecting segments "g" & "h"(Decimal point) to + 5V and grounding all other segments. now lets try displaying "3" , so you out put -10110000b or #0B0H to the port - you ground the segs which are to be seen( by writing zeros-0) and connect +5V to the segs which have to be hidden(by writing 1s).i hope you are using Common Anode (LTS542) 7 seg display , if you are using Common Cathode (LTS543) then you have to do reverse logic with the binary number you want to display.you draw the numbers you want to display on a paper and construct patterns 8 bit foreach number.Apart from having lookup table ready you should also have a Compare subroutine to CJNE the value stored in a register( ADC value which is stored) to the look up table.for eg: 33H is 00110011b which is a packed BCD number which is made up of two numbers - 3H and 3H after unpacking(higher nibble and lower nibble) you will get - 00000011b and 00000011 now store these two values in 2 variables say HI_Byte and LO_Byte. now compare Hi_byte in the sub routine with the Look up table and display1st digit , same way compare Lo_byte in the lookup table and display 2nd digit.you may have to mutliplex the digits or use CD4511 BCD decoders for each digithope this will solve your problemho boy it's been a lengthy Post - thanks to my patience Arun http://www.8051projects.net/forum-t9130.html 2009-01-08T12:17:17-08:00 pdi33 How many digits are u planning to connect to the uC?. Are u planning to display only numbers or also some alpha numeric characters? Please clarify.Actually, u need to interface a multiplexed LED display to the uC. If u clarify the above points, i can provide u a ciruit idea about the connection. http://www.8051projects.net/forum-t9130.html 2009-01-08T12:17:17-08:00 priya123 actually i want to display some numbers only. my project is somewhat like this: i have interfaced adc(0804) and microcontroller(8051) .on appling a voltage say 2volts adc displays 033h and display is seen through port1 of microcontroller.at first i saw the display through leds connected on my trainer kit but now i want to see the display through a 7-segment display.i am providing my program code ,please tell me what changes are to be made in the code?setb p2.5setb p2.6intr bit p2.7setb intradc_port equ p1adc_val equ 30hvoltage_val equ r3back: clr wr setb wr acall conversion read: clr rd mov a,adc_val setb rd mov r3,#00h acall data_display1 mov r3,#01h acall data_display2 mov r3,#02h acall data_display3 mov r3,#03h acall data_display4 mov r3,#04h acall data_display5 mov r3,#05h acall data_display6 sjmp back data_display1: mov a,#00h conversion: mov b,#0ah div ab mov r7,b mov b,#0ah div ab mov r6,b mov r5,a mov p1,r7 acall delay mov p1,r6 acall delay mov p1,r5 acall delay retdata_display2: mov a,#33h mov b,#0ah div ab mov r7,b mov b,#0ah div ab mov r6,b mov r5,a mov p1,r7 acall delay mov p1,r6 acall delay mov p1,r5 acall delay ret data_display3: mov a,#67h mov b,#0ah div ab mov r7,b mov b,#0ah div ab mov r6,b mov r5,a mov p1,r7 acall delay mov p1,r6 acall delay mov p1,r5 acall delay ret data_display4: mov a,#97h mov b,#0ah div ab mov r7,b mov b,#0ah div ab mov r6,b mov r5,a mov p1,r7 acall delay mov p1,r6 acall delay mov p1,r5 acall delay ret data_display5: mov a,#99h mov b,#0ah div ab mov r7,b mov b,#0ah div ab mov r6,b mov r5,a mov p1,r7 acall delay mov p1,r6 acall delay mov p1,r5 acall delay ret data_display6: mov a,#0ffh mov b,#0ah div ab mov r7,b mov b,#0ah div ab mov r6,b mov r5,a mov p1,r7 acall delay mov p1,r6 acall delay mov p1,r5 acall delay ret delay: mov r4,#200 here: djnz r4,here ret end http://www.8051projects.net/forum-t9130.html 2009-01-08T12:17:17-08:00 sashijoseph Hi Priya...Plz do not make multiple posts of the same topic....you have posted the same question in 3 diff. threads!!As for your problem...you would need to display 3 digits.So you need three multiplexed 7-seg displays as pdi33 pointed out.In multiplexing what you do is connect all the 7-seg displays in parallel,to one uc port,ie P1 in your case. Now Vcc to each display is provided by a transistor controlled by a port pin.So when the transistor connected to a particular display is switched on,only that display(out of the 3) will work.Similarly the next display will be made to turn on and the remaining will be off.When this cycle continues at a fast rate (greater than 20Hz) you get the impression that all 3 displays are on at the same time.Look at the attached ckt.The display is a common anode one.To switch any display on you'll have to write a 0 to the particular port pin(P2.0,P2.1 or P2.2). http://www.8051projects.net/forum-t9130.html 2009-01-08T12:17:17-08:00 sashijoseph For writing digits you'll have to send the fol. values to P1.Digit........ P1value(in hex)--------------------------------0........... C01........... F92........... A43........... B04........... 995........... 926........... 827........... F88........... 809........... 98 http://www.8051projects.net/forum-t9130.html 2009-01-08T12:17:17-08:00 pdi33 here is a simple idea for writing the display routine: (w.r.t the hardware suggested by shashi)first u define a byte say digit_count = 0. then folow the following stepsstep1: disable all digits (p2.0=p2.1=p2.2 = 1)step2: fetch seven-segment code for the particular digit corresponding to digit_count.step3: output the seven-segment code to port1step4: enable the selected digit (p2.0/p2.1/p2.2 = 0) depending upon the digit_count.step 5: increment the digit_count and reset it if it is > = 3.return.this routine should be called in the main loop and should be called continuously in real time.( rate of execution should be > 60hz. as the full display will be shown only when the routine is executed three times for the three digits.) http://www.8051projects.net/forum-t9130.html 2009-01-08T12:17:17-08:00 priya123 sir, i have another doubt------ the thing is that actually for a certain voltage say 2volts ,adc is reading 033h ,this data i am sending to the microcontroller and it is displaying 033h.i want 2 see 033h on the ports of the microcontroller through seven segment display. but here the digits 0-9 doesnt correspond to the values i have provided in my program. please help me clear this doubt. http://www.8051projects.net/forum-t9130.html 2009-01-08T12:17:17-08:00 sashijoseph Plz go through the previous posts.Your answer is there.For displaying digit '0' in the 7-seg,you have to send 'C0'.For displaying digit '1',you have to send 'F9'.....and so on.Read the above posts........ http://www.8051projects.net/forum-t9130.html 2009-01-08T12:17:17-08:00 Ajay please provide your circuit... http://www.8051projects.net/forum-t9130.html 2009-01-08T12:17:17-08:00 pdi33 here is a simple circuit for directly interfacing the 7 seg to uC without multiplexing which will require a little more hardware but the software is very easy. but note that the 7- segment display should be strictly common cathode.just convert ur binary input from the ADc into BCD and output it to port p2 and lower nibble of p3. i.e two digits on p2 and one digit on port 3.0 to p3.3. direct_display.pdf http://www.8051projects.net/forum-t9130.html 2009-01-08T12:17:17-08:00 priya123 sir,i hv enclosed the assembly language program code of my project,but at that time i was seeing the display through leds connected on my trainer kit, but as now i want to se the display through 7-segment display so i think some changes are to be made in my program code ,sir please tell me what are the changes to be made? http://www.8051projects.net/forum-t9130.html 2009-01-08T12:17:17-08:00 shyam where is the code?? http://www.8051projects.net/forum-t9130.html 2009-01-08T12:17:17-08:00 priya123 i had posted the code but somehow it didn't appear,anyways i am resending the code,please go through it and help me to find out what changes should i do to see the display through a 7-segment display.l CODE:setb p2.5
setb p2.6
intr bit p2.7
setb intr
adc_port equ p1
adc_val equ 30h
voltage_val equ r3
back:  clr wr
         setb wr
         acall conversion
 read:   clr rd
         mov a,adc_val
         setb rd
         mov r3,#00h
         acall data_display1
         mov r3,#01h
         acall data_display2
         mov r3,#02h
         acall data_display3
         mov r3,#03h
         acall data_display4
         mov r3,#04h
         acall data_display5
         mov r3,#05h
         acall data_display6
         sjmp back
  data_display1:  mov a,#00h
   conversion:    mov b,#0ah
                   div ab
                   mov r7,b
                   mov b,#0ah
                   div ab
                   mov r6,b
                   mov r5,a
                   mov p1,r7
                   acall delay
                   mov p1,r6
                   acall delay
                   mov p1,r5
                   acall delay
                   ret
data_display2:     mov a,#33h
                    mov b,#0ah
                    div ab
                    mov r7,b
                    mov b,#0ah
                    div ab
                    mov r6,b
                    mov r5,a
                   mov p1,r7
                    acall delay
                    mov p1,r6
                    acall delay
                    mov p1,r5
                    acall delay
                    ret
 data_display3:    mov a,#67h
                   mov b,#0ah
                   div ab
                   mov r7,b
                   mov b,#0ah
                   div ab
                   mov r6,b
                   mov r5,a
                  mov p1,r7
                   acall delay
                   mov p1,r6
                   acall delay
                   mov p1,r5
                   acall delay
                   ret
  data_display4:   mov a,#97h
                    mov b,#0ah
                    div ab
                    mov r7,b
                    mov b,#0ah
                    div ab
                    mov r6,b
                    mov r5,a
                    mov p1,r7
                    acall delay
                    mov p1,r6
                    acall delay
                    mov p1,r5
                    acall delay
                    ret
 data_display5:     mov a,#99h
                    mov b,#0ah
                    div ab
                    mov r7,b
                    mov b,#0ah
                    div ab
                    mov r6,b
                    mov r5,a
                    mov p1,r7
                    acall delay
                    mov p1,r6
                    acall delay
                    mov p1,r5
                    acall delay
                     ret
  data_display6:    mov a,#0ffh
                      mov b,#0ah
                      div ab
                      mov r7,b
                      mov b,#0ah
                      div ab
                      mov r6,b
                      mov r5,a
                     mov p1,r7
                      acall delay
                      mov p1,r6
                      acall delay
                      mov p1,r5
                      acall delay
                      ret
        delay:         mov r4,#200
        here:          djnz r4,here
                        ret
                        end                                
                                                                                                                       
                                        http://www.8051projects.net/forum-t9130.html 2009-01-08T12:17:17-08:00 Arun Kumar V Hi Priya123, did you read my earlier post in this thread ? it took a lot of my time to explain the whole concept in a simple way. Again your are back to square One and all you do is ask the same question again and again. other members too have tried their best to explain to you the concept even with diagrams but you don't want to learn .Please Note: it is minimum courtesy for you to thank the members who are trying to help you before you start your new post Arun http://www.8051projects.net/forum-t9130.html 2009-01-08T12:17:17-08:00 pdi33 Is the code for the 7segment display or for the simple LED display which u have written? please add circuit diagram or atleast the connections used by u for connecting the LED display. else it is difficult to follow the logic u have used. For e.g. note the following code:'data_display1: mov a,#00hconversion: mov b,#0ah'What does it exactly do? Is it the display driving routine or the ADC conversion routine .Always define the port pins with the respective functions as it makes the code more readable for u as well as for US Also mention whether u are using the direct display drive ( check circuit diagram posted by me in my previous post) or the multiplexed display as suggested by shashi. This is important as both methods require completely different code logic . http://www.8051projects.net/forum-t9130.html 2009-01-08T12:17:17-08:00 sashijoseph OK one last time.....You can do it this way... CODE:data_display6: mov a,#0ffh
mov b,#0ah
div ab
mov r7,b
mov b,#0ah
div ab
mov r6,b
mov r5,a
mov p1,r7
acall delay
mov p1,r6
acall delay
mov p1,r5
acall delay change to CODE:data_display6: mov a,#0ffh
mov b,#0ah
div ab
mov r7,b
mov b,#0ah
div ab
mov r6,b
mov r5,a
mov a,r7
acall disp_7seg
;mov p1,r7
acall delay
mov a,r6
acall disp_7seg
;mov p1,r6
acall delay
mov a,r5
acall disp_7seg
;mov p1,r5
acall delay for disp_7seg subroutine,you compare the value of 'a' with 0.If they match send 'CO' to P1.If not then compare 'a' with 1 and send 'F9' if they match.Similarly proceed with other digits upto 9.CJNE a,#0,D1mov p1,#0C0hD1:CJNE a,#1,D2mov p1,#0F9hD2:CJNE a,#2,D3mov p1,#0A4h . . . .ret http://www.8051projects.net/forum-t9130.html 2009-01-08T12:17:17-08:00 Arun Kumar V after a match is found it can jmp to calling routineCODE:disp_7seg:  CJNE a,#0,D1
                    mov p1,#0C0h
                    sjmp back
           
D1: CJNE a,#1,D2
        mov p1,#0F9h  
        sjmp back
           
D2:  CJNE a,#2,D3
        mov p1,#0A4h  
        sjmp back
.
.
.
.
.
back:  ret
 Arun http://www.8051projects.net/forum-t9130.html 2009-01-08T12:17:17-08:00 sashijoseph oops forgot the return after match.....thanks Arun for the correction. http://www.8051projects.net/forum-t9130.html 2009-01-08T12:17:17-08:00 priya123 sir,i have tried to simulate my program by the way u suggested,i hv tried to write the program code in that way,but i think still i hv made some mistakes,as its not working.when i am simulating my program it shows the following errors------in the disp_7segment subroutine if i write sjmp back then error shows ADDRESS OUT OF RANGE. Replacing sjmp back by ret it gives STACK OVERFLOW.Please sir help me to correct the errors.i am enclosing the code here------- setb p2.5setb p2.6intr bit p2.7setb intradc_port equ p1adc_val equ 30hvoltage_val equ r3back: clr wr setb wrconversion: acall conversion read: clr rd mov a,adc_val setb rd mov r3,#00h acall data_display1 mov r3,#01h acall data_display2 mov r3,#02h acall data_display3 mov r3,#03h acall data_display4 mov r3,#04h acall data_display5 mov r3,#05h acall data_display6 sjmp back data_display1: mov a,#00h mov b,#0ah div ab mov r7,b mov b,#0ah div ab mov r6,b mov r5,a mov a,r7 mov p1,r7 acall disp_7segment acall delay mov a,r6 mov p1,r6 acall disp_7segment acall delay mov a,r5 mov p1,r5 acall disp_7segment acall delay data_display2: mov a,#33h mov b,#0ah div ab mov r7,b mov b,#0ah div ab mov r6,b mov r5,a mov a,r7 mov p1,r7 acall disp_7segment acall delay mov a,r6 mov p1,r6 acall disp_7segment acall delay mov a,r5 mov p1,r5 acall disp_7segment acall delay data_display3: mov a,#67h mov b,#0ah div ab mov r7,b mov b,#0ah div ab mov r6,b mov r5,a mov a,r7 mov p1,r7 acall disp_7segment acall delay mov a,r6 mov p1,r6 acall disp_7segment acall delay mov a,r5 mov p1,r5 acall disp_7segment acall delay data_display4: mov a,#99h mov b,#0ah div ab mov r7,b mov b,#0ah div ab mov r6,b mov r5,a mov a,r7 mov p1,r7 acall disp_7segment acall delay mov a,r6 mov p1,r6 acall disp_7segment acall delay mov a,r5 mov p1,r5 acall disp_7segment acall delay data_display5: mov a,#97h mov b,#0ah div ab mov r7,b mov b,#0ah div ab mov r6,b mov r5,a mov a,r7 mov p1,r7 acall disp_7segment mov a,r6 mov p1,r6 acall disp_7segment mov a,r5 mov p1,r5 acall disp_7segment acall delay data_display6: mov a,#0ffh mov b,#0ah div ab mov r7,b mov b,#0ah div ab mov r6,b mov r5,a mov a,r7 mov p1,r7 acall disp_7segment mov a,r6 mov p1,r6 acall disp_7segment mov a,r5 mov p1,r5 acall disp_7segment acall delay disp_7segment: cjne a,#0,d1 mov p1,#0c0h ret d1: cjne a,#1,d2 mov p1,#0f9h ret d2: cjne a,#2,d3 mov p1,#0a4h ret d3: cjne a,#3,d4 mov p1,#0b0h ret d4: cjne a,#4,d5 mov p1,#99h ret d5: cjne a,#5,d6 mov p1,#92h ret d6: cjne a,#6,d7 mov p1,#82h ret d7: cjne a,#7,d8 mov p1,#0f8h ret d8: cjne a,#8,d9 mov p1,#80h ret d9: cjne a,#9,d10 d10: mov p1,#98h ret delay: mov r4,#200 here: djnz r4,here ret end thanking u, http://www.8051projects.net/forum-t9130.html 2009-01-08T12:17:17-08:00 priya123 sir,once again i tried to simulate the program by removing the statement CONVERSION:ACALL CONVERSION,program after being simulated shows no error ,in the previous case it was showing STACK OVERFLOW.but i just want to confirmis it the correct way i am programming???lease send a quick reply. thanking u sir http://www.8051projects.net/forum-t9130.html 2009-01-08T12:17:17-08:00 Arun Kumar V Hi Priya,CODE:setb p2.5
setb p2.6
intr bit p2.7
setb intr
adc_port equ p1
 adc_val equ 30h
voltage_val equ r3
back: clr wr
setb wr
conversion: acall conversion
read: clr rd
mov a,adc_val
setb rdhere are the two bugs i found :back: clr wrsetb wrconversion: acall conversion1) label name : back is already defined once and you are using it again in the disp_7seg routine, in my last post i used the sjmp back ( i didn't know that back label was already used )command just to avoid so many ret s, so the program was trying to sjmp (short jump) from disp_7seg routine to back label in the begininng of the program which is obviously out of address range ( in some cases when you get "out of range " error trying using LJMP command instead of SJMP)2) conversion: acall conversion - the program counter is stuck here indefinetly 3) tip : it is a good practice to First relocate the stack pointer beyond the 4 Register Banks Address & bit addressable ram ( from 20h) in the main routine - this avoids stack overflow/over writing you can use : MOV SP,#50H ; put this in the first line of your Main routine to relocate SP to some safe address which you'll not be using for your variables try these corrections and simulate Arun http://www.8051projects.net/forum-t9130.html 2009-01-08T12:17:17-08:00 pdi33 hi priya, looks like something is seriously missing in ur code.data_display1: mov a,#00hmov b,#0ah div ab -----here acc=0 and b =0ahmov r7,bmov b,#0ahdiv abmov r6,bmov r5,amov a,r7mov p1,r7 -------here r7 will always bear a value 00h from ur code i feel that the segments of display are connected to port p1.now in the above code there is no mention of the register r3 nor is the adc_val u have put in accumulator. So please check the logical flow of ur routine. also mention the hardware connections of the adc and display to the uC to avoid further confusion. http://www.8051projects.net/forum-t9130.html 2009-01-08T12:17:17-08:00 sashijoseph CODE:mov r6,b
mov r5,a
mov a,r7
mov p1,r7
acall disp_7segment
acall delay
mov a,r6
mov p1,r6
acall disp_7segment
acall delay
mov a,r5
mov p1,r5
acall disp_7segment
acall delay Comment out or remove the fol. lines in the code above(as well as in all the other display routines).1)mov p1,r72)mov p1,r63)mov p1,r5 http://www.8051projects.net/forum-t9130.html 2009-01-08T12:17:17-08:00 priya123 thanx a lot a shash sir,arun sir n pdi33 sir,my program has now started working.its all because of ur guidance,thanx .