Some Questions About Workings of a GLCD

[Utku1]

Hello,

I am trying to use a GLCD for my project. Looking at the module's and its drivers' datasheets, some questions have formed in my mind. The links to datasheets are as follows:

**broken link removed** for the datasheet of the GLCD module.
Link for the datasheet of the GLCD module's segment drivers.
Link for the datasheet of the GLCD module's com driver.

My questions are a bit lengthy but if you could have time to answer them, I would be very very grateful. So if you would excuse, my questions are as follows:

1) First of all, why aren't pin numbers of the drivers shown at the block diagram at p.10 of the LCD module's datasheet? Also, not every signal's name is shown as well. Am I supposed to be able to understand how the module works without knowing which signal goes to where in the module?

2) In the display module's block diagram (at p.10 of the module's datasheet), CS1 and CS2 are connected to their respective segment drivers. Also, there are 8+5 pins connected to each segment driver from the MPU. On the other hand, in the application circuit given in p.20 of the NT7108C datasheet, all CS1B, CS2B and CS3 signals are connected to all segment drivers. Furthermore, there are 8+7 pins connected to each segment driver from the MPU, instead of 8+5 pins. Now what is the meaning of this? Where are the remaining 2 pins connected from in the display module's diagram? Also, why aren't CS1 and CS2 connected to both segment drivers in module's diagram, unlike the application circuit given in p.20 of NT7108C?

3) In the p.6 of the datasheet of NT7108C, pins; CS1B, CS2B and CS3 are defined as follows:

"Chip selection
In order to interface data for input or output, the terminals have to be CS1B=L, CS2B=L, and CS3=H."

and throughout the entire document, only that given combination of CS1B, CS2B and CS3 is mentioned. My question is: If only a single combination is being used, why are there 3 pins provided for a single task, instead of just 1?

4) Another point is, I couldn't figure out how am I supposed to connect the GLCD module to my MCU, an ATmega32. I heard that conventionally, SPI is used to connect peripherals to an MCU, but thing is, SPI uses serial connection and the GLCD module that I use has a parallel port for data transfer. So I am a bit confused here also.

5) My last question is, I came across a tutorial on this page about the use of the GLCD. They put an architecture diagram (named: "GLCD pages") in the website and it explains the form of the architecture very well. My question is, how were they able to understand that architecture is in that way? If that's by looking at the datasheets, could you please underline the places in the datasheets that helped them coming with that architecture diagram? If the sources were not the datasheets, but the experiments they have performed using the module, then my question is: Are there many cases where datasheets of components does not provide enough information and hence, one needs to understand the architecture by conducting experiments, rather then by thoroughly reading the provided datasheets?

I realize that the questions I asked have been lengthy but if you could have time to explain the answers of these questions, I would be really grateful. Thank you very much in advance.

Sincerely

 

[milan.rajik]

Which Compiler are you using ?

 

[Utku1]

Actually none. I am planning to write the code for my application on the AVR Assembler. The reason for my questions are actually to understand how the module works internally. For example, I can't understand why the block diagram at p.10 of the LCD module's datasheet does not contain the pin numbers on the driver ICs? Is it because the module manufacturer does not want to disclose the details of the module, or is it simply omitted erroneously?

 

[Utku1]

I see. Thanks for the reply. So in that case, the block diagram in the module's datasheet might have been omitted altogether, right? Because it doesn't provide any useful information without having the pin numbers of the driver ICs?

 

[Utku1]

One more thing: For example at p.10 of the module's datasheet, we observe that there is only a single chip select (CS) pin coming into a single segment driver from the MPU. On the contrary, on the application circuit diagram at p.20 of NT7108C datasheet, we see that there are 3 chip select pins coming out of the MPU and going into all segment drivers. So this suggests that, the remaining 2 chip select pins are internally wired in the GLCD module. So my question is: If only a single chip select pin is being used in the module, why does NT7108C has 3 chip select pins, instead of 1?

 

[FvM]

For example, I can't understand why the block diagram at p.10 of the LCD module's datasheet does not contain the pin numbers on the driver ICs? Is it because the module manufacturer does not want to disclose the details of the module, or is it simply omitted erroneously?

Neither, I believe. It's primarly omitted because no typical user of the module cares about.

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Because it doesn't provide any useful information without having the pin numbers of the driver ICs?

Actually not much information. But page 10 is giving the impression of a technically profound and informative datasheet, isn't it?

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I think we are approaching the point where too much detail information is rather confusing a user than being helpful.

Regarding function of external connected chip selects, you should really refer to the module datasheet. There are separate chip selects for display memory halves, as with many other GLCD devices. Means onyl one of three segment driver CS pin is externally connected. From a users viewpoint, it's about to "useless information" how many additiona.
l CS signals the segment driver provides.

 

[Utku1]

I see. Thanks everybody for their kind attention.

Regards