# pic16f628 and lcd

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#### dawson

##### New Member
hi,
I have just started learning how to use pics and have been following nigel goodmans tutorials. I am upto tutorial 3.1 but am having problems.

When I turn on the circuit all I get is a line full of black squares (just the top line). I have tried to register on his forums to ask for help but am still awaiting confirmation.

I have looked around these forums for similar problems and think that there could be 2 possible reasons for this.

The first reason is that I am not using a hitachi 44780 lcd. I am using this lcd which uses a Samsung KS0066U controller but have since read that this should be compatible with the 44780?

The second thing I have read is that it could be because I am using a LVP programmer, but there should be ways around this where I can still use my home made programmer?

Any help would be appreciated

#### birdman0_o

##### Active Member
Black line means the LCD is not receiving any information, are you sure that your hardware is set up right?

That LCD should be compatible by the way. Did you tie RA4 high?

#### dawson

##### New Member
Yes I am pretty sure its setup I followed the schematic on nigels tutorial. RA4 goes to pin 4 on the lcd and then has a 10k resistor connecting it to pin 2 which is +5v

#### birdman0_o

##### Active Member
Are you sure the chip programmed right?

#### dawson

##### New Member
No I am unsure because I have a home made LVP programmer however I have tried tutorials 1 and 2 on nigels site and they worked fine. When programming this code I had the same resullt and it verified fine. I can also read the code back and everything seems to be there.

#### birdman0_o

##### Active Member
Ok, are you 100% sure the LCD is wired right? Can you upload a picture?

#### Wp100

##### Well-Known Member
Hi,

Its always a problem getting your first lcd to run when you have no other reference to go by.

To help 'see' your program is running make it flash a led before it goes into the lcd routine proper and then again at the end of the lcd routine.

#### dawson

##### New Member
yes i have checked it a few times, the only difference is that I did not have a 10k resistor so have tried a 15k and a 4.7k as this is all I have to hand, both give the same result. I have wired it on breadboard so it will be a bit hard for you to check connections using a picture but i will try and sort them out a bit and upload a pic.

#### dawson

##### New Member
Wp100, that sounds like a good idea but this is only my third test circuit so dont really know how to go about doing that.

Would it be just as simple as adding nigels tutorial 1 to the begining of this program?

#### fantabulous68

##### Member
When I turn on the circuit all I get is a line full of black squares (just the top line). I have tried to register on his forums to ask for help but am still awaiting confirmation.
yes i have checked it a few times, the only difference is that I did not have a 10k resistor so have tried a 15k and a 4.7k as this is all I have to hand, both give the same result.

Yikes....I'm also a beginner and lol started using a LCD recently, and the same thing happened to me when I USED A DIFFERENT VALUE POTENTIOMETER than that recommended from the datasheet. It was always the POT giving me problems.

My LCD worked when:

1. I used the correct value POT
2. Made sure my pot wires were fastened properly & connected the right way

Hope this helps......

#### birdman0_o

##### Active Member
Yikes....I'm also a beginner and lol started using a LCD recently, and the same thing happened to me when I USED A DIFFERENT VALUE POTENTIOMETER than that recommended from the datasheet. It was always the POT giving me problems.

My LCD worked when:

1. I used the correct value POT
2. Made sure my pot wires were fastened properly & connected the right way

Hope this helps......

A pot is a voltage dividing resistor and would not have been the problem. The problem was probably that your pot was broken.

#### fantabulous68

##### Member
The problem was probably that your pot was broken.
Yeah guaranteed.

#### dawson

##### New Member
I am using a 10k pot rather than a 5k pot in nigels circuit but thie is just used for contrast and other circuits use a 10k pot? gonna re organise bread board now

#### blueroomelectronics

##### Well-Known Member
Did you try the LED solution as mentioned earlier?

#### dawson

##### New Member
birdman0_o: I have re-wired the circuit again but it isnt really any clearer so not much point in taking a pic, I will get some different colour wires tomorrow however im pretty sure that it is wired correctly.

blueroomelectronics: Not yet I went to get something to eat and just got back. I am still a bit unsure how I go about doing it. Do I just add it to the code from tutorial one?

#### birdman0_o

##### Active Member
that is one way to do it
be careful though, make sure that you do not change pins to inputs when they are supposed to be outputs and vice versa...You can just add in a small loop...

using nigels code though

Code:
BSF PORTB,0
CALL Delay255
BCF PORTB,0
CALL Delay255

Thats all you need

#### blueroomelectronics

##### Well-Known Member
I take it you're very new to assembly. Skip the LCD until you come to grips with flashing an LED

#### birdman0_o

##### Active Member
He says hes already done it
I have tried tutorials 1 and 2 on nigels site and they worked fine

#### dawson

##### New Member
birdman0_o: what do you mean use nigels code aswell? add your code to nigels lcd code? or use his flashing led code and yours and the lcd code?

blueroomelectronics: Yes I am brand new lol. I have tried those tutorials but didnt "get to grips" with the code, they worked fine but I didnt understand why. maybe I should go back through untill I have a better understanding.

#### dawson

##### New Member
well there deffinately seems to be a problem with either the pic or programming the pic, just went back to tutorial 1 n now nothing happens

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