PIC16F876 4 bits Display in 16x2 LCD
Discussion in "PIC Microcontroller Discussion" started by pappuneelam May 1, 2011.
Sun May 01 2011, 11:59 am
Halo!
The below mentioned ASM code is for 4 bit LCD display with 16F876A. Using RB0,RB1,RB2 for RS,R/W,E and RC0,1,2,3 for DB4,DB5,DB6,DB7 of LCD.
My problem is that the code is working on OshonSoft simulator with only 'A 0', i.e. where as it should print 'R1'. Moreover, there is a blank space between A and 0. Its taking the MSB of the A first and then taking 0000 in the next sending of LSB.
Also, not getting any display over with PIC16F876A & LCD panel.
I tried in vein, but not geting any solution. Please help me.
PappuNeelam
********
The below mentioned ASM code is for 4 bit LCD display with 16F876A. Using RB0,RB1,RB2 for RS,R/W,E and RC0,1,2,3 for DB4,DB5,DB6,DB7 of LCD.
My problem is that the code is working on OshonSoft simulator with only 'A 0', i.e. where as it should print 'R1'. Moreover, there is a blank space between A and 0. Its taking the MSB of the A first and then taking 0000 in the next sending of LSB.
Also, not getting any display over with PIC16F876A & LCD panel.
I tried in vein, but not geting any solution. Please help me.
PappuNeelam
********
; 4 bit interface with LCD 16x2, using PIC 16F876A
; using PORT B: RB0, RB1 & RB2 as RS, R/W & E line
; using PORT C: RC0, RC0, RC2 RC3 as DB4, DB5, DB6 & DB7
__CONFIG H'39B1' ; set the configuration word
; ***************** Set up the constants **************************
STATUS equ 03h
TRISA equ 85h
TRISB equ 86h
TRISC equ 87h
PORTA equ 05h
PORTB equ 06h
PORTC equ 07h
COUNT1 equ 20h ;counter1 for delay loop
COUNT2 equ 21h ;counter2 for delay loop
COUNT3 equ 22h ;counter3 for delay loop
COUNT4 equ 23h ;counter4 for delay loop
COUNT5 equ 24h ;counter5 for delay loop
COUNT6 equ 25h ;counter6 for delay loop
COUNT7 equ 26h ;counter2 for delay loop
COUNT8 equ 27h ;counter3 for delay loop
; *******Ports setup *******
org 00h
bsf STATUS,5 ; shift to Bank1
movlw 00h
movwf TRISB ; set PortB to output mode
movlw 00h
movwf TRISC
bcf STATUS,5 ; return to Bank0
; ******Turn the Port pins *******
Start
call Delay
call Init
movlw 05h
movwf PORTC
call Data_control
call Delay1
movlw 02h
movwf PORTC
call Data_control
call Delay1
movlw 03h
movwf PORTC
call Data_control
movlw 01h
movwf PORTC
call Data_control
call Loop
; ******** Command & Data Function ********
Command_control
movlw 04h
movwf PORTB ; use RB0,RB1,RB2 for RS,R/W,E
call Delay1
movlw 00h
movwf PORTB
return
; ******** Data Function *********
Data_control
movlw 05h
movwf PORTB ; use RB0, RB1, RB2 for RS,R/W,E
call Delay1
movlw 01h
movwf PORTB
return
;********* Functions Definitions********
Init
movlw 20h
movwf PORTC
call Command_control
call Delay1
movlw 00h
movwf PORTC
call Command_control
call Delay1
movlw 0Fh
movwf PORTC
call Command_control
call Delay1
return
;************* Delay subroutine - 4mS interval *****************************
Delay
loop1 decfsz COUNT1,1 ; decrease 1 from 255
goto loop1
loop2 decfsz COUNT2,1 ; decrease 1 from 255
goto loop2
loop3 decfsz COUNT3,1 ; decrease 1 from 255
goto loop3
loop4 decfsz COUNT4,1 ; decrease 1 from 255
goto loop4
loop5 decfsz COUNT5,1 ; decrease 1 from 255
goto loop5
loop6 decfsz COUNT6,1 ; decrease 1 from 255
goto loop6
loop7 decfsz COUNT7,1 ; decrease 1 from 255
goto loop7
loop8 decfsz COUNT8,1 ; decrease 1 from 255
goto loop8
return
;************* Delay1 subroutine - 1.5mS interval *****************************
Delay1
loop9 decfsz COUNT1,1 ; decrease 1 from 255
goto loop9
loop10 decfsz COUNT2,1 ; decrease 1 from 255
goto loop10
return
Loop
loop13 decfsz COUNT1,1 ; decrease 1 from 255
goto loop13
incfsz COUNT1,1 ; decrease 1 from 255
goto loop13
return
end ; end of the program
Sun May 01 2011, 03:14 pm
Sorry;
Its displaying 'P 0' (not 'A 0'), instead of 'R1'. There is a blank space between P and 0.
PappuNeelam
Its displaying 'P 0' (not 'A 0'), instead of 'R1'. There is a blank space between P and 0.
PappuNeelam
Mon May 02 2011, 02:28 pm
; ******Turn the Port pins *******
Start
call Delay
call Init
movlw 05h
movwf PORTC
call Data_control
call Delay1
movlw 02h
movwf PORTC
call Data_control
call Delay1
movlw 03h
movwf PORTC
call Data_control
movlw 01h
movwf PORTC
call Data_control
call Loop
************
Through this, i`m getting prints in the LCD of OshonSoft simulator. Inspite of getting 'R1', its displaying 'P--0' & having a two blank spaces between P & 0.
PappuNeelam
Start
call Delay
call Init
movlw 05h
movwf PORTC
call Data_control
call Delay1
movlw 02h
movwf PORTC
call Data_control
call Delay1
movlw 03h
movwf PORTC
call Data_control
movlw 01h
movwf PORTC
call Data_control
call Loop
************
Through this, i`m getting prints in the LCD of OshonSoft simulator. Inspite of getting 'R1', its displaying 'P--0' & having a two blank spaces between P & 0.
PappuNeelam
Mon May 02 2011, 10:02 pm
try this..
movlw 'R' ;then call lcd function movlw '1' ;call lcd data function
Tue May 03 2011, 11:10 am
Mr. Ajay,
I tried with your suggestion. But, now its printing nothing, except blanks. Its now taking LSB of R[52]0101 0010 as MSB of Blank space [0010 0000]. And I tried with S[53]0101 0011, but printing is '0'.
I thing, there is some wrong in my ASM code.
I tried with your suggestion. But, now its printing nothing, except blanks. Its now taking LSB of R[52]0101 0010 as MSB of Blank space [0010 0000]. And I tried with S[53]0101 0011, but printing is '0'.
I thing, there is some wrong in my ASM code.
Fri May 06 2011, 06:30 pm
; Program for LCD HD44780 display
; Using XT 4Mhz
;****************************************************************
;Declaration and Configuration of the processor
PROCESSOR PIC16F876A
#include <P16F876A.inc>
__CONFIG H'39B1' ; set the configuration word
; ************* Macros & Constants ***********
BANK0 macro
Bcf STATUS,RP0 ;Select memory bank 0
Endm
BANK1 macro
Bsf STATUS,RP0 ;Select memory bank 1
Endm
COUNT1 equ 20h ;counter1 for delay loop
COUNT2 equ 21h ;counter2 for delay loop
COUNT3 equ 22h ;counter3 for delay loop
COUNT4 equ 23h ;counter4 for delay loop
COUNT5 equ 24h ;counter5 for delay loop
; ********* Ports setup ************
ORG 00h
goto Main
Main
BANK1
movlw 00h
movwf TRISB ; set PortB to output mode
movlw 00h
movwf TRISC
BANK0
; *************Sending Data to LCD***************
call Delay
call Init
movlw 'R'
movwf PORTC
call Data_control
call Delay
call Loop
; ************** Command Function *************
Command_control
movlw 04h
movwf PORTB ; use RB0,RB1,RB2 for RS,R/W,E
call Delay1
movlw 00h
movwf PORTB
return
; ************** Data Function ****************
Data_control
movlw 05h
movwf PORTB ; use RB0, RB1, RB2 for RS,R/W,E
call Delay1
movlw 01h
movwf PORTB
return
;************** Initialise Function ************
Init
movlw 20h
movwf PORTC ; Function Set for 4 bits, 2 lines, 5x7 dots
call Command_control
call Delay
movlw 02h
movwf PORTC
call Command_control
call Delay
movlw 00h
movwf PORTC
call Command_control
call Delay
return
;************* Delay subroutine :2mS *****************************
Delay
loop1 decfsz COUNT1,1 ; decrease 1 from 255
goto loop1
loop2 decfsz COUNT2,1 ; decrease 1 from 255
goto loop2
loop3 decfsz COUNT3,1 ; decrease 1 from 255
goto loop3
loop4 decfsz COUNT4,1 ; decrease 1 from 255
goto loop4
return
;************* Delay1 subroutine :1mS ****************
Delay1
loop5 decfsz COUNT1,1 ; decrease 1 from 255
goto loop5
loop6 decfsz COUNT2,1 ; decrease 1 from 255
goto loop6
return
; *********** Hold the Program ******************
Loop
loop7 decfsz COUNT1,1 ; decrease 1 from 255
goto loop7
incfsz COUNT1,1 ; increase 1 to 1
goto loop7
return
end ; end of the program
Sat May 07 2011, 12:26 am
Your 4-bit initialization of LCD is not right. I suggest you to visit tutorial section and read about 4-bit mode of LCD. That will give you a clear idea of where you're doing wrong.
Mon May 09 2011, 05:57 pm
Mr. Ajay,
As per ur suggestion, I changed my Initialisation section for 4 bits. and its now working well on Simulator. But, I haven`t checked on physical devices. I will try on weekends. Thanks a LOT !!!!!!!!
But, no instruction/commeands are working or any effects on the code, like.. 0Fh, 0Eh,01h,C0h.
The 0Fh, 0Eh are need to be in Initialisation subroutine, but no effect.
The 01h,C0h are need after printing any data.
As per ur suggestion, I changed my Initialisation section for 4 bits. and its now working well on Simulator. But, I haven`t checked on physical devices. I will try on weekends. Thanks a LOT !!!!!!!!
But, no instruction/commeands are working or any effects on the code, like.. 0Fh, 0Eh,01h,C0h.
The 0Fh, 0Eh are need to be in Initialisation subroutine, but no effect.
The 01h,C0h are need after printing any data.
; Program for LCD HD44780 display
; Using XT 4Mhz
; Using PIC16F876A
;*****************PORT Pins *********************************
; Using RA1,RA2 [PORTA] for RS & R/W pins of LCD
; Using RB0 [PORTB] for E pins of LCD
; Using RC0,RC1,RC2,RC4 for D4,D5,D6 & D7 pins of LCD
;************************************************************
; Declaration and Configuration of the processor
PROCESSOR PIC16F876A
#include <P16F876A.inc>
__CONFIG H'39B1' ; set the configuration word
; ************* Macros & Constants ***********
BANK0 macro
Bcf STATUS,RP0 ;Select memory bank 0
Endm
BANK1 macro
Bsf STATUS,RP0 ;Select memory bank 1
Endm
COUNT1 equ 20h ;counter1 for delay loop
COUNT2 equ 21h ;counter2 for delay loop
COUNT3 equ 22h ;counter3 for delay loop
COUNT4 equ 23h ;counter4 for delay loop
COUNT5 equ 24h ;counter5 for delay loop
COUNT6 equ 25h ;counter6 for delay loop
COUNT7 equ 26h ;counter7 for delay loop
COUNT8 equ 27h ;counter8 for delay loop
COUNT9 equ 28h ;counter9 for delay loop
COUNT10 equ 29h
; ********* Ports setup ************
ORG 00h
goto Main
Main
BANK1
movlw 00h
movwf TRISA ; set PortA to output mode
movlw 00h
movwf TRISB ; set PortB to output mode
movlw 00h
movwf TRISC ; set PortC to output mode
BANK0
; *************Sending Data to LCD***************
;variable counter = 1
;call Loop_Long
call Delay ; Power Up the LCD controller
call Init ; Initialize the LCD Controller
movlw 05h ; Print 'P'
movwf PORTC
call Data_control
movlw 00h
movwf PORTC
call Data_control
movlw 04h ; Print 'A'
movwf PORTC
call Data_control
movlw 01h
movwf PORTC
call Data_control
movlw 05h ; Print 'P'
movwf PORTC
call Data_control
movlw 00h
movwf PORTC
call Data_control
call Sc_Clear ; Clear the LCD Screen
call Loop
; ************** Command Function *************
Command_control
movlw 00h
movwf PORTA
movlw 01h
movwf PORTB
call Delay2
movlw 00h
movwf PORTB
return
; ************** Data Function ****************
Data_control
movlw 02h
movwf PORTA ; use RB0,RB1 for RS,R/W
movlw 01h
movwf PORTB ; Data of PORTC move to LCD
call Delay2 ; Delay of 1.5 mS
movlw 00h
movwf PORTB
movlw 00h
movwf PORTA
return
;************** Initialise Function ************
Init
movlw 03h
movwf PORTC
call Command_control
movlw 03h
movwf PORTC
call Command_control
movlw 03h
movwf PORTC
call Command_control
movlw 02h
movwf PORTC ; Function Set for 4 bits, 2 lines, 5x7 dots
call Command_control
call Delay
movlw 02h ; Entry mode : 4 bits, 2 lines
movwf PORTC
call Command_control
call Delay1
movlw 08h
movwf PORTC
call Command_control
call Delay1
movlw 00h ; Enable Display / Cursor
movwf PORTC
call Command_control
call Delay1
movlw 08h
movwf PORTC
call Command_control
call Delay1
movlw 00h ; Cursor Blink
movwf PORTC
call Command_control
call Delay1
movlw 0Eh
movwf PORTC
call Command_control
call Delay1
return
;************* Delay subroutine :5mS *****************************
Delay
loop1 decfsz COUNT1,1 ; decrease 1 from 255
goto loop1
loop2 decfsz COUNT2,1 ; decrease 1 from 255
goto loop2
loop3 decfsz COUNT3,1 ; decrease 1 from 255
goto loop3
loop4 decfsz COUNT4,1 ; decrease 1 from 255
goto loop4
loop5 decfsz COUNT5,1 ; decrease 1 from 255
goto loop5
loop6 decfsz COUNT6,1 ; decrease 1 from 255
goto loop6
loop7 decfsz COUNT7,1 ; decrease 1 from 255
goto loop7
return
;************* Delay subroutine :1.5mS ****************
Delay1
loop9 decfsz COUNT1,1 ; decrease 1 from 255
goto loop9
loop10 decfsz COUNT2,1 ; decrease 1 from 255
goto loop10
return
;************* Delay Subroutine : 350 uS ***************
Delay2
movlw 7Dh
movwf COUNT1
loop8 decfsz COUNT1,1 ; decrease 1 from 255
goto loop8
return
; *********** Hold the Program ******************
Loop
loop11 decfsz COUNT1,1 ; decrease 1 from 255
goto loop11
incfsz COUNT1,1 ; increase 1 to 1
goto loop11
return
; *********** Clear the screen ******************
Sc_Clear
movlw 00h
movwf PORTC
call Command_control
call Delay1
movlw 01h
movwf PORTC
call Command_control
call Delay1
return
end ; end of the program
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