Write data to LCD

[SneaKSz]

Hello,

after being able to initialise my LCD, I want to send data to it. The thing that I dont understand is that , when I send data it it displayed for a short amount of time and then it's gone. If I use a loop with a delay it is being displayed but refreshed often and it gives an overlay effect.

My question is how I can make a stable view of data on the display?
View attachment LCD4.asm

Thanks in advance !

 

[ericgibbs]

Hello,

after being able to initialise my LCD, I want to send data to it. The thing that I dont understand is that , when I send data it it displayed for a short amount of time and then it's gone. If I use a loop with a delay it is being displayed but refreshed often and it gives an overlay effect.

My question is how I can make a stable view of data on the display?
View attachment 45560

Thanks in advance !

hi,
The LCD has inbuilt memory, it does not require refreshing.?
If its going blank, make sure you are not going back to the origin at 0x0000 and reinitialising the LCD.

 

[SneaKSz]

Hello,

Well as you can see in my modified code .
View attachment LCD4.asm


I use initlcd to set up the LCD. That works fine , after that I call "figure" , and write " sneaksz " to the output. After that I wait( loop ) .

I just see a blinking cursor on my display. If I change the infinite loop to , goto figure. Then my display is full of characters .

I don't know if my LCD has a built in memory. The datasheet is less then less.

If I send data then it's displayed for a short amount of time and then it's gone.


I also tried your modified code for my pic18f14k50( thread initialise LCD ), I can compile the code but there is no HEX file after compiling :s.


Greets

 

[ericgibbs]

hi,
My problem is I dont have a model for your PIC type.
I'll try to figure out a solution...

EDIT:
I changed the include file in your listing to 18F452 so that I can run it.
Without any other changes I get an LCD display as shown in this image from the Simulator.

 

[SneaKSz]

Is there something that I can help with?

DS : https://www.electro-tech-online.com/custompdfs/2010/08/40247-1.pdf

The routines of sending data are normally well configured.

It's just weird it shows the data so shortly!

EDIT :

Is that program PIC simulator IDE?

EDIT2 : I get the same text

I don't get whats wrong if the simulator says it's correct.
thanks

 

[ericgibbs]

Is there something that I can help with?

DS : https://www.electro-tech-online.com/custompdfs/2010/08/40247-2.pdf

The routines of sending data are normally well configured.

It's just weird it shows the data so shortly!

EDIT :

Is that program PIC simulator IDE?


thanks

hi,
I have your LCD d/s from yesterday.
What puzzles me is that I cannot see any RAM addresses.??????

 

[SneaKSz]

hi,
What puzzles me is that I cannot see any RAM addresses.??????

Ow , so the data that is being send , isn't stored , thats why its always just in a flash that i see the data .

So I have to write data to DDRAM?

 

[ericgibbs]

Ow , so the data that is being send , isn't stored , thats why its always just in a flash that i see the data .

So I have to write data to DDRAM?

hi,
The d/s you posted today, does show a 80 * 8 data RAM.

 

[SneaKSz]

hi,
The d/s you posted today, does show a 80 * 8 data RAM.

I don't even know what that means . Can you tell me how to store the data into those ram addresses?

I think I have to set the DDRAM address and then move data to the datalines so the data is stored?

Thanks in advance.

 

[ericgibbs]

I don't even know what that means . Can you tell me how to store the data into those ram addresses?

I think I have to set the DDRAM address and then move data to the datalines so the data is stored?

Thanks in advance.

hi,
Its a 2 line display, 1st line has 0 to 39 and second 40 to 79 RAM locations for the characters you write to the display.
Look at this clip from the d/s.

I have been checking thru your code, it looks OK. The only minor point is this.

bcf RS ; RS low
        MOVLW 0x02 ; Clear displ,,, [B]this is HOME not CLR[/B]
        movwf ctemp
        call writeLCD        
        movlw 0x01 ; 1*100µs=100µs
        movwf delay2
        call delay

 

[SneaKSz]

Thanks for the information , I tried to apply it :

; write sneaksz to the LCD 
figure
;set  DDRAM  location 
		bcf RS ; write an instruction 
		call endelay ; this is necessary ! 
		movlw 80h ; function set DDRAM address  : " 00h , position 1" is this correct? 
		movwf ctemp		
		Call writeLCD ;write is to the LCD 
; the start of the word
		bsf RS		; send data
		call endelay
		MOVLW 53h  ; send  S
		movwf ctemp		
		Call writeLCD

EDIT 2 : Forgot a delay

Thanks in advance

 

[SneaKSz]

Its all working now in 8 bit modeView attachment LCD4.asm

 

[ericgibbs]

Its all working now in 8 bit modeView attachment 45583

hi,
Thanks for letting me know, at least you are sure the LCD is A OK.
Do you need any more help with the program.?

 

[SneaKSz]

hi,
Thanks for letting me know, at least you are sure the LCD is A OK.
Do you need any more help with the program.?

Hello ,
Well I can display data on the LCD now , as you said once before I need a negative voltage for the contrast. Well I found a program that creates a negative voltage from a PWM signal. I tested that and I get that negative voltage. The only thing is that the PWM pin CCP1(RC5) is for this and I use it to send data to the LCD ( I use PORTC).
PWM :

I'm going to rewrite the program for a 4 bit and use the RC5 as CCP1 supplied to the contrast input.

The only thing is that If i move data to the output , I only use 4 bits of PORT C and I don't want to use bsf/ bcf , it will take ages .

Is there some kind of trick for that? I opened another post for this .

Thanks in advance

 

[ericgibbs]

Hello ,
Well I can display data on the LCD now , as you said once before I need a negative voltage for the contrast. Well I found a program that creates a negative voltage from a PWM signal. I tested that and I get that negative voltage. The only thing is that the PWM pin CCP1(RC5) is for this and I use it to send data to the LCD ( I use PORTC).
PWM :

I'm going to rewrite the program for a 4 bit and use the RC5 as CCP1 supplied to the contrast input.

The only thing is that If i move data to the output , I only use 4 bits of PORT C and I don't want to use bsf/ bcf , it will take ages .

Is there some kind of trick for that? I opened another post for this .

Thanks in advance

hi,
Will the final project have UART with say a MAX232.??
If yes, you can use the -9V on the MAX232 pin for the LCD.

 

[SneaKSz]

It won't have that . Just displaying data , thats all !

 

[ericgibbs]

hi,
You could use one of these IC's

 

[SneaKSz]

hi,
You could use one of these IC's

Thanks for the link , I've seen that IC before. I needed it once in a project ,but I used a 555 (+diodes and C's)then to make a negative voltage.

I just want to use the CCP1 pin and my LCD in 4 bit mode to reduce the cables.

Isn't it possible to send a nibble to the a port of a piece of a byte? ( without bsf/bcf)

 

[Nigel Goodwin]

The only thing is that If i move data to the output , I only use 4 bits of PORT C and I don't want to use bsf/ bcf , it will take ages .

Why would it take ages?, PIC's are incredibly fast - the only speed constraints are the LCD itself, which runs FAR slower than a PIC.

 

[SneaKSz]

Why would it take ages?, PIC's are incredibly fast - the only speed constraints are the LCD itself, which runs FAR slower than a PIC.

It will take ages TO WRITE that program , if I have to set every bit , isn't there a smoother way!