Go Down

Topic: Help connecting a GLCD (Read 171 times) previous topic - next topic

TheCamoc

Im trying to get a GLCD to work it uses a SED-1520DAA Controller and is on adapterboard Named LCD-12232. The Datasheet and some other Fotos are here. I searched on the internet but didnt find how to connect it, because my Pins arent the same as in guides.

bperrybap

sed1520 displays are very tricky. For some reason there seems to be many different ways they are wired up and each uses different signals with different names and requires different ways of communicating.
Some are really funky like a russian version that flips pixels around but only on half the display.

openGLCD has support for several different sed1520 displays and signal pin designs which can found here:
https://bitbucket.org/bperrybap/openglcd/wiki/Home
The display you have seems to be using the same signals as the mtb368.
The pain with that display is coming up with the 2khz clock signal.
Here are some additional threads about the mtb368:
https://hellocrispyking.wordpress.com/tag/cat-tracker/
https://forum.pjrc.com/threads/26112-GLCD-MTB-368-%28122*32-SED1520%29-with-openGLCD-and-Teensy-3-0

openGLCD comes with a configuration file for the mtb368. You can use that or at least start with that and modify the Arduino pin numbers if want/need to.
Just be sure to wire the pins from the Arduino according to the signal name and glcd pin # in your document and not use the glcd module pin numbers documented in the table in the config file.
So just ignore the "Pin" column in the table in the mtb368 config file and use the glcd pin numbers from your documentation.
For example:
The AO/DI signal (glcdPinDI or arduino pin A3) will connect go your glcd module pin 1 not pin 4 as shown in the mtb368 config file table.


--- bill

TheCamoc

I think i got everything hooked up correctly but the Cl pin in the Config it says Must supply Clock Speed but i dont know what to connect it to.

bperrybap

The CL pin is a clock input. You must supply that with a 2Khz 50% duty cycle clock signal.
Like I said that is what makes using that glcd a pain.
You have to come up with some way of generating a 2khz clock signal to feed to that pin.
You can use external circuitry or you can use an Arduino pin.
If using an Arduino pin you could use a PWM pin output to create the needed 50% duty cycle signal but you will have to change the PWM frequency to something close to 2Khz.
How you do that varies depending on the micro-controller used.
On some of the teensy boards it is easy as Teensy has additional/better APIs than stock Arduino.
You can see how it was done on Teensy 3 with the sample code provided in the links I provided earlier.
You can google around but here for more information.
Here are some links that might get you started if you are  using one of the AVR based boards:
http://forum.arduino.cc/index.php?topic=212519.0
http://playground.arduino.cc/Code/PwmFrequency
https://arduino-info.wikispaces.com/Arduino-PWM-Frequency


--- bill

TheCamoc

Ok now i think my GLCD has its clock speed on the board i checked and there are 2,4 Volts on the Port. But still my Board doesnt work still. I dont have my RES and Backlight connected but i think i dont need them connected or do I? What do i have to change in my openGLCD Config? And is there any Way i can test if the GLCD still works i think i might have killed it by testing before.

bperrybap

You should take some time to read the documentation included with the library.
(Not just what is on the project repo page)
There is quite a bit about how to configure the library for the display type and for the pin usage.
There is also information on how to use the diagnostic sketch and trouble shooting.


I am not sure what you mean by:
Quote
i think my GLCD has its clock speed on the board i checked and there are 2,4 Volts on the Port
If you are referring to the clock signal, the clock signal is a pulse it is not a voltage. If you hook it up to a scope or logic analyzer it should show up as a 2khz pulse train with a 50% duty cycle.

glcd modules typically will not show anything until the wiring is all correct the lcd is initialized and the contrast setting is correct.
RES is VERY necessary. The signal level on that pin controls how the interface works.
Spend some additional time looking over the other mtb368 projects in the links I provided and look at the mtb368 config file included with openGLCD.
It describes how to hook up that signal.

As far as backlight goes, it depends on the display. Some use positive pixels (dark on light background) and some use negative pixels (light on dark background). If you have a negative pixel display, then you will not see any pixels unless the backlight is on.

You will also have to figure out Vee is. i.e what type of signal (input or output) and voltage level.
I'm assuming is really the Vo contrast voltage signal input.
If so, this is typically a -5 to +5 variable voltage that controls the contrast of the pixels.
(some use 0 to 5v, but that is not as common)
The pixels will not show up properly until the contrast is correct and this requires getting that signal correct.
To low of a voltage and all pixels on the module will be on, too high and no pixels will be on.
Just right will have only the pixels that are supposed to be on actually on.

The mtb368 used in the projects referenced above worked with nothing attached to the Vo signal.
(You can see this in the links provided and in the config file provided with openGLCD)
Most glcds that have a Vo signal require some sort variable negative voltage fed to that pin and include a pin (normally called Vee) that provides the base negative voltage that can be controlled wit a pot. While your glcd has a signal called Vee, this doesn't make sense as Vee is normally an output signal. That is why I'm assuming your Vee signal is really a Vo contrast level input signal.
If you are really lucky your display will work with nothing connected to the Vee signal, assuming your Vee signal is really a Vo signal.
If it does not work with nothing connected, you will have to figure what voltage level makes the pixels show up. If it needs a voltage and you are lucky, the voltage needed for good contrast is between 0 and 5v and you can use a simply pot to create that. If not, you will have to have second power supply to create the needed base negative voltage and use a pot to adjust from there.


You will have be to very careful when doing any experimental testing as hooking things up incorrectly can cause permanent damage to the glcd or the Arduino or both.
This is why I said read as much as you can about the other project and library documentation to try to avoid any incorrect connections.

For sed1520 modules I prefer the vk5121 as it has everything needed including backlight control.
It is very easy to hook up and get running as you don't need any external components and only requires connects to arduino pins.

--- bill



Go Up
 


Please enter a valid email to subscribe

Confirm your email address

We need to confirm your email address.
To complete the subscription, please click the link in the email we just sent you.

Thank you for subscribing!

Arduino
via Egeo 16
Torino, 10131
Italy