New Project on Obsoleted Part

dusty20 said:

64128E and the one on the left is the 64128COG

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Interesting that Vss and Vdd are not in order. 16/18 pins match and two do not?
I am not saying that the data is wrong. I am saying that you should double check that.
Not like there would be an error in a data sheet.
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Left side pins 15 & 17 are connected together so if you swap 17 down to 15 then all the wires are in order.

DrG said:

Actually wouldn't a DISPLAYTECH 64128COG be close? There are a few around that seem to be available like here https://www.ebay.com/itm/DISPLAYTECH-64128COG-CCTW-DISPLAY-128X64-R4S5-7B4-/302324784180 or **broken link removed**

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Looking at these two listings I can't tell if either of them have a backlight? I could use the backlight on the one I have right now which should theoretically work.

dusty20 said:

The one on the right is the 64128E and the one on the left is the 64128COG. I didn't see the LED but I'm sure I can figure that out. The spec sheet says refer to KS0713 all over the place. I knew that COG was chip on glass but wasn't sure what that meant compared to something with a driver IC. Also, since it didn't state a driver I wasn't sure how it functioned since the others use the driver to decipher the code and relay it to specific pixels.

View attachment 119810

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Yeah, there is lots to this...I hope I am not coming across as condescending because, while I have written a couple of simple display libraries and have used quite a few LCDs with PICS and Arduinos and a few others, I am by no means an expert.

To me, ya got your LCD, and you got your controller chip (KS0713) and you got your driver (in firmware in your case). Both the E and COG "boards" have the same controller (on glass in the case of the COG variety and on the board of the E variety). Somewhere, you have an MCU that sets up the controller and then interacts with it regularly to display what need to be displayed. I am going through this to be on the same page...well, more accurately, because that is how I am viewing the situation. IOW I think about the "driver" as the code that interacts with the controller.

The KS0713 datasheet is here https://www.crystalfontz.com/controllers/Samsung/KS0713/

You mentioned that you hooked up a different board and it worked but was some kind of mirror image...that is actually a good sign in a way. Same with a recommended display that was compatible except for something like that. I remember an ST controller on a board that had a hardware signal to invert the screen or something similar. So, my point is that, yes, if it worked except for that anomoly, you quite possible could fix it in software. But, how do you get at it inside the product because that is likely a major obstacle.

So, my thinking is that you need to replace the LCD + controller and you need the same interface connections. It becomes a nightmare when you don't have the schematic to your product. The COG display *could* work, but there are probably a few reasons why it might not. Again, if you had a schematic that showed the interface to the controller, it would help.

Sorry, I know that this is not all that helpful.

s

DrG said:

Yeah, there is lots to this...I hope I am not coming across as condescending because, while I have written a couple of simple display libraries and have used quite a few LCDs with PICS and Arduinos and a few others, I am by no means an expert.

To me, ya got your LCD, and you got your controller chip (KS0713) and you got your driver (in firmware in your case). Both the E and COG "boards" have the same controller (on glass in the case of the COG variety and on the board of the E variety). Somewhere, you have an MCU that sets up the controller and then interacts with it regularly to display what need to be displayed. I am going through this to be on the same page...well, more accurately, because that is how I am viewing the situation. IOW I think about the "driver" as the code that interacts with the controller.

The KS0713 datasheet is here https://www.crystalfontz.com/controllers/Samsung/KS0713/

You mentioned that you hooked up a different board and it worked but was some kind of mirror image...that is actually a good sign in a way. Same with a recommended display that was compatible except for something like that. I remember an ST controller on a board that had a hardware signal to invert the screen or something similar. So, my point is that, yes, if it worked except for that anomoly, you quite possible could fix it in software. But, how do you get at it inside the product because that is likely a major obstacle.

So, my thinking is that you need to replace the LCD + controller and you need the same interface connections. It becomes a nightmare when you don't have the schematic to your product. The COG display *could* work, but there are probably a few reasons why it might not. Again, if you had a schematic that showed the interface to the controller, it would help.

Sorry, I know that this is not all that helpful.

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Well you are certainly lightyears ahead of me. And I haven't taken any of this as condescending. I don't play with PCB's, displays or anything like that. normally I trace an electrical issue to a board and realize yea thats bad time to get a new one. Since it isn't possible to just get a drop in replacement I am trying to learn some more and get a working product in the end. At the beginning of this which was about 2 weeks ago I had no idea there were different chips and I thought all I had to do was find one with the same number of pins - I was really clueless.

My terminology is usually all over the place and rarely is correct. I was using driver and IC interchangeably. That makes sense the way you described it. I might not be reading it correctly but would your fear be that even though the COG has the KS0713 it may have a different firmware which would still not allow it to work?

I am not sure exactly what you are looking for in a schematic, I have found a lot of datasheets that have combinations of wire diagrams and pinouts which I can try to find and post here but I want to make sure I am getting the right things. So are you looking for the schematic that would show the wiring for the 64128E and how the pins connect to the chip and the backlight for both of the options or are you looking for something more than that? As far as the schematic on the main modules PCB I doubt I will find anything for that. I assume it is custom made for their product. It does have an MCU on it. I have been using the pinout for the 64128E assuming the pins on the main modules pcb will be the same as it was soldered directly together.

If I could reverse the image on the 64128N through hardware that would be ideal! there are a few pads on the displytech pcb that you can solder bridge or tie together somehow, I didn't want to start guessing with that.

ronsimpson said:

Interesting that Vss and Vdd are not in order. 16/18 pins match and two do not?
I am not saying that the data is wrong. I am saying that you should double check that.
Not like there would be an error in a data sheet.
----------------edited--------------
Left side pins 15 & 17 are connected together so if you swap 17 down to 15 then all the wires are in order.

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Thanks, I was purely going off of the title on each pin and didn't even look at the schematic.

dusty20 said:

Looking at these two listings I can't tell if either of them have a backlight? I could use the backlight on the one I have right now which should theoretically work.

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I noticed that also on the one that I looked at the most...where were the anode and cathode connections? I don't know...I have an LCD from the 1980s or so and it has no backlight. I had a fantasy of building my own portable terminal....I take it out and look at it ever so often and think...maybe I should get that working for S&G (if anybody recognizes it and has any data, let me know....bought it off of the back of a BYTE magazine...I did work out the connections at one time I think...if I remember it is also 40 X 2, which at the time was pretty cool....now not so much

dusty20 said:

Looking at these two listings I can't tell if either of them have a backlight? I could use the backlight on the one I have right now which should theoretically work.

Click to expand...

is there a commercial off the shelf item that these COG displays plug into or will I need to solder each connection? I think they are too close to use female jumper wires designed for header pins right?

dusty20 said:

My terminology is usually all over the place and rarely is correct. I was using driver and IC interchangeably. That makes sense the way you described it. I might not be reading it correctly but would your fear be that even though the COG has the KS0713 it may have a different firmware which would still not allow it to work?

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Well, sort of, but that they both use the same controller is a good thing and being a COG should not be too much of a problem...it is just that you are flying blind to some degree. Hey, if you can find some fun out of this and keep it on the cheap, go for it I say.

Re your 40x2 display. I had a 16x2 that had similar pinout with the backlight at the opposite end. I think it's the same as this.

Mike.

DrG said:

I noticed that also on the one that I looked at the most...where were the anode and cathode connections? I don't know...I have an LCD from the 1980s or so and it has no backlight. I had a fantasy of building my own portable terminal....I take it out and look at it ever so often and think...maybe I should get that working for S&G (if anybody recognizes it and has any data, let me know....bought it off of the back of a BYTE magazine...I did work out the connections at one time I think...if I remember it is also 40 X 2, which at the time was pretty cool....now not so much View attachment 119811

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That thing looks pretty robust. I wouldn't know where to start.

dusty20 said:

is there a commercial off the shelf item that these COG displays plug into or will I need to solder each connection? I think they are too close to use female jumper wires designed for header pins right?

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If you have the pin spacing, you can slap them on a board like this one (which has gathered some dust since I did it. Note that although this is a COG LCD, it is using an I2C interface so there are fewer connections. It had 'funky' pin spacing and I had to find a board to match that (the little blue piece) and then, along with a few components, put it on a standard perfboard (the green piece)...it does work well.



...you sure you want to do this?? If so, keep getting advice/opinions from others here - many have far more experience than I.

DrG said:

Well, sort of, but that they both use the same controller is a good thing and being a COG should not be too much of a problem...it is just that you are flying blind to some degree. Hey, if you can find some fun out of this and keep it on the cheap, go for it I say.

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I appreciate yours and everyone else's help so far. Yes it has been very interesting finding this stuff out. I doubt I'll ever get to the point that I actually program one. This would have to be frustrating if you were designing a product and something like this is no longer produced you would just be SOL... I guess they have a time frame in mind for how long they plan to be in production.

I have an email in to both of the listings on there to see if they have a backlight and if they will ship to the US for something less than an arm and a leg. The unfortunate part is I wouldn't get it for about 3 weeks or so - that's a lot of waiting.

Pommie said:

Re your 40x2 display. I had a 16x2 that had similar pinout with the backlight at the opposite end. I think it's the same as this.

Mike.

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I think it is something like that...same parallel interface but it predates HD4478 or 1602. Somewhere I have a folder with whatever I could dig up, including the add in Byte...I can't remember off the top of my head, but I always looked at their stuff...not John Bell, but something like that.

EDIT: I have to correct myself, it IS an HD44780A00 controller. Maybe it is not as old as I think it is...also there are 4 Sanyo LC7930 drivers. It is *very* similar to **broken link removed**, except mine has an 88 stamped where that was has a 9x stamp....and socket pins rather than the ribbon. Humph, I probably could try to get this thing working! (I don't know if I should thank you guys or curse you)....and a datasheet!!

DrG said:

If you have the pin spacing, you can slap them on a board like this one (which has gathered some dust since I did it. Note that although this is a COG LCD, it is using an I2C interface so there are fewer connections. It had 'funky' pin spacing and I had to find a board to match that (the little blue piece) and then, along with a few components, put it on a standard perfboard (the green piece)...it does work well.

View attachment 119812

...you sure you want to do this?? If so, keep getting advice/opinions from others here - many have far more experience than I.

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I might as well keep trying whats the worst that could happen I make an unusable thing more unusable ha!

I figure I'll give it one more go with the COG option and potentially try one of the 5V options. It still baffles my mind that you can have two boards that are identical looking and pinout with the same 8 bit parallel interface and when you plug them in it just doesn't work.

be80be said:

Convert the standard 5V type LCD to 3.3V - Codrey Electronics

Nowadays most popular microcontrollers are working on 3.3V but many liquid crystal displays (LCDs) for them are usually on 5V, because they are centered on Hitachi’s de facto standard LCD controller – the HD44780 chip. […]

www.codrey.com

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Thanks for sending that, I will read into it and potentially try it with a ks0107 lcd which should also be a Samsung brand hopefully similar to the ks0713.

Pommie said:

Re your 40x2 display. I had a 16x2 that had similar pinout with the backlight at the opposite end. I think it's the same as this.

Mike.

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The text LCD modules (Hitachi based) use the same pinouts, in two variants, either SIL or DIL. I've got a couple of the 2x40 I bought a great many years ago, importing them from the USA.

Essentially all displays are 2x40, just with a smaller 'window' on the 40 char display lines.

This doesn't help the OP though, as he has a non-universal graphic display.

Nigel Goodwin said:

This doesn't help the OP though, as he has a non-universal graphic display.

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Indeed, just trying to help DrG.

Mke.

Pommie said:

Indeed, just trying to help DrG.

Mke.

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It is off-topic, but it looks like there is, indeed, enough information out there to test that old Optrex display that I posted. I believe it has a date code of 1988 but it also looks like they made them well into the 90s. I may try testing it out today and will post any positive results in another thread.

I have one on order. I should be able to tell the results in about 2-4 weeks.