Pages: [1]   Go Down
Author Topic: This Winstar LCD  (Read 1391 times)
0 Members and 1 Guest are viewing this topic.
0
Offline Offline
Full Member
***
Karma: 0
Posts: 142
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Hi I have just bought this Winstar LCD:
http://www.rapidonline.com/Electronic-Components/Winstar-Graphic-Display-Negative-Blue-Mode-128-x-64mm-White-LED-Backlight-57-2278

i am using the u8glib library for graphical LCDs, written by Oliver Kraus. I cant get it to work (except the backlight...)
I have it set up like this on the mega 2560:
U8GLIB_KS0108_128 u8g(7, 8, 9, 10, 11, 12, 13, 22, 23, 24, 4, 5, 25);
According to Oliver, it should be wired like this:
U8GLIB_KS0108_128 u8g(d0, d1, d2, d3, d4, d5, d6, d7, en, cs1, cs2, di, rw [, reset])

and I am trying to run the hello world example. I have checked my connections again and again, and I cant find a problem. the only confusion is the LCD nas  "negative voltage output" pin, and I read that some LCD's need negative voltage. Could this be it, and if so how do I accomplish that?

I have reset wired to pin 25.

Any ideas on things to try. I cant get hello world to appear!
Thanks

I have the variable pin (I assume for contrast) connect to VCC via a 10K resitor
Logged

Western New York, USA
Offline Offline
Faraday Member
**
Karma: 32
Posts: 4245
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
I have checked my connections again and again, and I cant find a problem.
We can't help check your connections unless you provide a photograph.

Quote
... the only confusion is the LCD nas  "negative voltage output" pin, and I read that some LCD's need negative voltage. Could this be it, and if so how do I accomplish that?
This may not be your only confusion.  The connections are shown in the diagram at the bottom of page 6.  
-One end of the potentiometer goes to VDD (+5V, pin 2).
-The other end of the potentiometer goes to Vout (this is the "negative voltage output pin", pin 18).
-The center (wiper) of the potentiometer goes to VO (LCD Operating Voltage, pin 3).


Quote
I have the variable pin (I assume for contrast) connect to VCC via a 10K resitor
????????

Don
« Last Edit: November 16, 2012, 08:12:14 pm by floresta » Logged

0
Offline Offline
Full Member
***
Karma: 0
Posts: 142
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Right gotcha.
I have (pin 18) Vout going through a 10K resistor to Vo (pin 3), I then have a 10K resistor going from pin 3 to vcc.

Has anyone a small program that I can use to test if the lcd is working, and because at the moment I am using the u8glib library and the only thing im not sure about is whether U8GLIB_KS0108_128 is the right class to use for this lcd?
Logged

Western New York, USA
Offline Offline
Faraday Member
**
Karma: 32
Posts: 4245
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
I have (pin 18) Vout going through a 10K resistor to Vo (pin 3), I then have a 10K resistor going from pin 3 to vcc.
If the manufacturer knew what the appropriate voltage for VO was they would have specified two resistors to be used in a voltage divider as you have described.  Since that voltage is unknown, and changes with variables such as temperature, they have specified the use of a potentiometer which is essentially a variable voltage divider.

Quote
Has anyone a small program that I can use to test if the lcd is working,
You will not be able to tell if it is working until you get the LCD Operating Voltage (aka 'contrast') set correctly.

Don
Logged

0
Offline Offline
Full Member
***
Karma: 0
Posts: 142
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

OK, Im surprised if that wouldnt work though, they say 10-20K and I am reading the value in the middle of to 10K's i.e a resistance of 10K...?
Logged

Western New York, USA
Offline Offline
Faraday Member
**
Karma: 32
Posts: 4245
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
they say 10-20K
That means that you can use a potentiometer that measures anywhere between 10K and 20K as measured between the ends.  The overall value is not critical but you must be able to vary the ratio between each end and the wiper.

Don
Logged

0
Offline Offline
Full Member
***
Karma: 0
Posts: 142
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Thanks
I'll give it a go tonight then, It surprises me tha the pot is whatyou guys think is the problem, I would have thought If Im getting nothing through te issue would seem greater.
I'll tell you how it goes.
Thanks
Alex
Logged

Western New York, USA
Offline Offline
Faraday Member
**
Karma: 32
Posts: 4245
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Quote
I would have thought If Im getting nothing through te issue would seem greater.
How would you know if anything is getting through or not if the display is not working?

Don
Logged

0
Offline Offline
Full Member
***
Karma: 0
Posts: 142
Arduino rocks
View Profile
 Bigger Bigger  Smaller Smaller  Reset Reset

Hi guys, finally managed to get a variable resistor. I've added it to the circuit and as I turn it I can see the contrast changing. I cant however get anythiing to display. i am using the u8glib library still. is there anyway to find out whether ive damaged it?]
thanks
Logged

Pages: [1]   Go Up
Jump to: