Just checked!!!! You need external pullups on port 0...

 

Just checked!!!! You need external pullups on port 0...

I didn't understand, Do you mean I have to use five pullup resistor's. I think 10K would be fine

 

Port 0 hasn't any internal pullups, so I normally use 4k7, but 10 will be fine CS1, CS2, RS, RW and E need to be high when not being used..

 

Port 0 hasn't any internal pullups, so I normally use 4k7, but 10 will be fine CS1, CS2, RS, RW and E need to be high when not being used..

Can I use other port pin's that have internal pullups?

 

Port 3 is a good one to use...

 

Draw you schematics...

I have doubt on Pin 3 connection also I have shown how I am going to connect pullup resistor

 

Port 3 is a good one to use...

Okay If I use port P3 then I will have not use to pullup resistor right ?

Please check the LCD connection of pin 3 (V0). Is it right ?

#define GlcdDataBus  P2
sbit RS  = P3^0;
sbit RW  = P3^1;
sbit EN  = P3^2;
sbit CS1 = P3^3;
sbit CS2 = P3^4;

 

With reference to this portion only and in view of the above discussion about Vo and Vee:


You have Vo tied directly to Vdd. That won't work. What is the purpose of the 220 (?) ohm resistor to ground? It will still be at Vdd voltage.

 

Yeah. Port zero is unique in that you have to use pull up resistors. P1-3 have pull ups.

 

Okay... There has been confusion!!! Vo is contrast... This will be around -15v... Pin 18 is Vout ( Vee ) and will give -17v, you need to put a pot like this... Connect pin 3 to Vee (pin 18) of the LCD... Connect pin 1 to 5V ( pin 2 ) and the center tap to Vo ( pin 3 )..

connect to 5v and ground..
Then adjust the pot until the contrast is black then back it off until the black just ( only just ) disappears...
Then when you run in the system the words will be viewable...

No need for pullups when using P3... I tend to use P3 to control external devices..

 

I made the new connection. I am using Port P2 for Data and P3 for Others Pins.

 

Nope!!!!!!



This way!!!!!

 

What is meaning of Pot, I think Potential resistor I missed it

View attachment 153813

Nope!!!!!!

View attachment 153814

This way!!!!!

My mistake. I didn't get the meaning of pot (Potential resistor)

 

Yeah!! Sorry.... Pot short for Potentiometer... I use a 10k one...

 

Yeah!! Sorry.... Pot short for Potentiometer... I use a 10k one...

I searched pot in my component's box. I don't have Potentiometer. Is it fine If I use only 10K resistor?

 

No! It has to be a potential difference... So.... try two resistors
vout --- 1k----- Vo ---- 10k --- 5V.

If its too dark
Vout --- 2k-----Vo ----- 8k1 --- 5V.

Etc...

You are trying to get the contrast visible... Vo needs to be -13V ~ -15V ( ish ) with reference to 5V

 

I have to go out now, so I won't be able to help for a while..

 

No! It has to be a potential difference... So.... try two resistors
vout --- 1k----- Vo ---- 10k --- 5V.
You are trying to get the contrast visible... Vo needs to be -13V ~ -15V ( ish ) with reference to 5V

Thank you Ian for being to the end.. God bless you

Thanks to all of you for your help...

I can show the message on screen

 

I have to go out now, so I won't be able to help for a while..

You have been already helped me a lot..

 

Cool!!

You didn't need to start a new thread.... We can carry on here!!