My graphical LCD

[airspirit]

Aw, crap ... does anyone know where to get one of those in the US?

[airspirit]

Okay, so do all the LCDs with that contoller use that same 20 pin set? Also, do you need to install the pots for the brightness and stuff, or is that only if you want to fine tune it?

Is this the one here?

http://www.futurlec.com/LED/LCD240X128pr.shtml

[Turbokeu]

Originally posted by airspirit
Okay, so do all the LCDs with that contoller use that same 20 pin set? Also, do you need to install the pots for the brightness and stuff, or is that only if you want to fine tune it?

Is this the one here?

http://www.futurlec.com/LED/LCD240X128pr.shtml

Unfortunately there is no "real" standard in the connections.

I know about three different 20 pin connectors for 240x128 LCDs:
1) the 20 pin connector as used on my T6963 based Powertip and also on the Datavision LCDs.
2) The 20 pin connector as used on the T6963 based Nan Ya LCDs.
3) The 20 pin connector as used on the SED1330 based LCDs.

I also found T6963 based 240x128 LCDs with a 32 pin connector as on the Truly (but as far as I investigated it should be no problem to use them too)

They do not specify the manufacturer of the LCD at Futurlec (Various?), without the datasheet it's quite difficult to judge...

The contrast potmeter is always needed. There is a temperature controlled contrast regulation on the LCD PCB itself around the manual setting of the potmeter, as the negative voltage (Vo) for the LCD is strongly dependant of the ambient temperature.

The luminosity potmeter (only with LED backlights) is optional (you could just use the appropriate serial resistor for the LEDs and leave the BL always at maximum luminosity).

With EL or CCFL backlight it's more tricky to regulate the luminosity because they are fed by a 5V invertor (comparable to the 12V invertors for CCFLs as used in case lighting).

The reset circuitry could be optional too (the switch anyway).
I know that some LCDs have the reset on power on resistor (R1) and capacity (C1) integrated on the LCD PCB, but others don't.

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[airspirit]

I really want to find one of those graphical ones ... that software package is just plain sweet. Unfortunately, I can't seem to find a reliable supplier other than the one in NL, and I don't ship across the pond if I can help it. I'll just keep looking.

Can you post which pin goes to what post on the parallel cable and how you laid out your PCB? That way even if the pinset on one I can find is different I'll still be able to set it up off of the spec sheet.

edit: and where can I find that DataVision one? Gawd, there are how-tos everywhere, but I can't find the darned LCD!

[Turbokeu]

Originally posted by airspirit
I really want to find one of those graphical ones ... that software package is just plain sweet. Unfortunately, I can't seem to find a reliable supplier other than the one in NL, and I don't ship across the pond if I can help it. I'll just keep looking.

Can you post which pin goes to what post on the parallel cable and how you laid out your PCB? That way even if the pinset on one I can find is different I'll still be able to set it up off of the spec sheet.

edit: and where can I find that DataVision one? Gawd, there are how-tos everywhere, but I can't find the darned LCD!

For the schematic for a Powertip or Datavision LCD see above in my thread (available also in PDF format).

For the connection schematic for a Nan Ya or a SED1330 based LCD see: http://gfxlcd.schijf.org/ (it's a Netherlands website with info about LCDs)
In the left frame choose "Schema's".

Powertip has a website in the US, so you should be able to find a reseller.

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[airspirit]

I think I found one at LCDMODKIT that only runs $65+16 ship out of Hong Kong. I'm going to prolly give that a shot ... it is green/black like the one at modwarehouse, and I'll just have to try to decipher the language at that site, hehe. I'm not about to spend three times that to order from modwarehouse, hehe.

[airspirit]

err, do you know what the amp pull on one of these things is going to be? I'm looking at a 5V/1.5A plug supply, and I'm not sure if that'll do the trick or not ....

Here is another option:
http://www.mpja.com/productview.asp?product=14469+OP

It says 5V logic / -20V drive on it ... does that mean I need to supply both, or are there onboard regulators ... this is confusing the bejeezus out of me.

[Turbokeu]

Originally posted by airspirit
I think I found one at LCDMODKIT that only runs $65+16 ship out of Hong Kong. I'm going to prolly give that a shot ... it is green/black like the one at modwarehouse, and I'll just have to try to decipher the language at that site, hehe. I'm not about to spend three times that to order from modwarehouse, hehe.

This LCD should be OK. It needs the connection diagram for the Nan Ya LCD, with the following modifications:

1. The -12V side of the 10K contrast potmeter should go to pin 19 (Vee) of the LCD (the LCD has an integrated negative voltage charge pump for contrast control)
2. Following the datasheet the LCD must be reset at power on, so you need resistor R1 and capacitor C1 as in my schematic but connected to pin 9 (RST) of the LCD.
3. Font Selection signal FS is pin 18 on your LCD (not pin 19 as in the schematic) and should be connected to +5V.
4. On the Nan Ya schematic the data lines (DB0-DB7) are pins 11 to 18. On your LCD it is pins 10 to 17.
5. The datasheet is not very clear about the backlight specifications: it says it needs a forward voltage of 4.0 to 4.2V.
Since this LCD is a green/yellowish one, backlight LEDS are probably green or yellow LEDS (or a combination of the two).
Those above LED colors have a forward voltage each of 2.0 to 2.1V, so probably there are two leds in series to obtain the 4.0-4.2V forward voltage.
The problem is that we don't know HOW MUCH LEDs in total the BL is made of...so it's quite difficult to calculate the serial resistor for the BL.
Example:
Assuming there would be six leds in total (and 20mA per serial LED branch) : 3 parallel connections of 2 LEDs in series = 60mA.
The BL should be connected to the +5V through the following serial resistor (and taken into account the two limits given for the forward voltage:
(5-4.2)/0.06 = 13.33 Ohm (nearest E12 value is 12 Ohm)
(5-4.0)/0.06 = 16.66 Ohm (nearest E12 value is 15 Ohm)

I hope this sounds not too complicated...
Feel free to ask if you have more questions.

CD

Edit: Avoid green/yellow LCD's, they tend to be boring... (it's just my 0.05$)

[Turbokeu]

Originally posted by airspirit
err, do you know what the amp pull on one of these things is going to be? I'm looking at a 5V/1.5A plug supply, and I'm not sure if that'll do the trick or not ....

Here is another option:
http://www.mpja.com/productview.asp?product=14469+OP

It says 5V logic / -20V drive on it ... does that mean I need to supply both, or are there onboard regulators ... this is confusing the bejeezus out of me.

My Powertip draws about 35mA typical on the +5V line (not including the backlight current which is 120mA in my case).
A 500mA to 1A power supply should be largely sufficient but be sure it's voltage regulated (most cheap wall mounted power supply aren't...). The tolerance on the +5V line of LCDs is maximum 10% (4.5 to 5.5V).

About this LCD:
- It's only 240x64 pixels.
- It doesn't have a builtin negative voltage charge pump, so you need a separate -20V voltage...

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[airspirit]

Thanks. I'm going to order that lcdmodkit setup. I'll let you know what's up as things progress (with pics). I don't mind green/yellow ... the color is a nicety that IMHO isn't worth doubling the price. I'm more of the utilitarian type of person.

[airspirit]

Wait ... couldn't I just pull the LEDs out and replace them with white ones for a black and white display? That would be shweet ...

[Turbokeu]

Originally posted by airspirit
Wait ... couldn't I just pull the LEDs out and replace them with white ones for a black and white display? That would be shweet ...

Sorry but that doesn't work, the LCD color itself is different in case of a green, white or blue LCD...
(When I remove the white BL and the white diffusor of my LCD, the glass is still blue)
BTW, green CCFL backlighted LCDs are backlit by a white CCFL.

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[TerraMex]

And :

White leds consume up to 100mA . The ones i bought to poke around do. I went "Whoa". But they are VERY bright. About three of those can light up a whole room, just like a flashlight.

And also :

Most LCD's , at least the ones i've seen, have a small film attached to the glass which gives a specific color to the glass. And most blacklit LCD's, that use el-wire type filament, it needs to be replaced.

[Turbokeu]

Originally posted by TerraMex
White leds consume up to 100mA . The ones i bought to poke around do. I went "Whoa". But they are VERY bright. About three of those can light up a whole room, just like a flashlight.

Those are more "starlight" LEDs than standard white LEDs then.
Standard white LEDs are specified for about 20mA as most other standard LEDs.

Most LCD's , at least the ones i've seen, have a small film attached to the glass which gives a specific color to the glass. And most blacklit LCD's, that use el-wire type filament, it needs to be replaced.

Right.
The MTBF of a LED BL is about 50,000 to 100,000 hours.
The MTBF of a CCFL BL is about 10,000 to 20,000 hours.
The MTBF of an EL BL is about 2,000 to 5,000 hours.

CD

[airspirit]

Okay, I'm looking at the following power plug:

http://www.allelectronics.com/cgi-bi...513&type=store

This is a regulated one, so it SHOULD be good, methinks. I'm ordering a 10K pot for the contrast and a 1K on/off pot for the brightness (it uses 4.2V IIRC, this allows me to turn it off if I don't want it on). I'm going to fuse out the PSU like you did (500 mA or so). So, this leaves me with the following parts that I'll need, right?

Momentary switch
10 Ohm/.5W resistor
12K Ohm/.25W resistor
100nF capacitor (regular type, I assume)

That sound about right?

[Turbokeu]

Originally posted by airspirit
Okay, I'm looking at the following power plug:

http://www.allelectronics.com/cgi-bi...513&type=store

This is a regulated one, so it SHOULD be good, methinks. I'm ordering a 10K pot for the contrast and a 1K on/off pot for the brightness (it uses 4.2V IIRC, this allows me to turn it off if I don't want it on). I'm going to fuse out the PSU like you did (500 mA or so). So, this leaves me with the following parts that I'll need, right?

Momentary switch
10 Ohm/1W resistor
12K Ohm/.25W resistor
100nF capacitor (regular type, I assume)

That sound about right?

The PSU seems OK, but it uses a not very common connector on the DC side (for PSU's I mean).

The 10K pot for the contrast is OK.
The 12K/.25W should be 10K/.25W (you probably inversed the numbers of the 2 resistors)
100nF is OK.

For the 12 Ohm/1W we don't know for sure since we don't have the specs for the current draw of the BL. The forward voltage only doesn't mean anything.

I disagree for the 1K luminosity pot. I tried a 1K and yes you can turn the luminosity down to 0%, but the practical use of the pot resides only within the first one or two tenths of a turn.
I use a 100 Ohm and I can regulate the luminosity from 100% to about 25% (or less, it's difficult to judge) over a complete turn of the pot. Maybe a 500 Ohm (or 470) value would be better for you.

CD

[airspirit]

Geez, you're a helpful one, aren't you?

Okay, revised list (I'll just order from allelectronics once I have confirmation I'm good ... Rat Shack here is teh sux):

SPST N.O. MOMENTARY PUSHBUTTON
5 VDC 1 AMP SWITCHING POWER SUPPLY
10 OHM 1/4 WATT
112 OHM 3 WATT SAND
10K LINEAR PC MOUNT POT
500 OHM SQ. TRIM POT
0.1UF DIP CAPACITOR
36 PIN FEMALE CONNECTOR, PC MOUNT
RJ-45 CORD COUPLER, STRAIGHT THROUGH FOR DATA
6' CABLE WITH RJ-45 CONNECTORS
GMA FUSE HOLDER, PC MOUNT
1/2 AMP 3AG FUSE
SOLDERABLE PERF BOARD

Think that'll do the trick? I assume I'll use the same pinout on the centronix connector, just moving the other end to the appropriate pin, and that this allows me to use a printer cable, right?

edit: thinking 16 gauge wire throughout ... the wire just slides into the holes of the centronix conn, right?

[airspirit]

Well, hopefully that was right cos I ordered it (I want it here when the LCD arrives). Anything else I may be able to find here, so ....

[Turbokeu]

Originally posted by airspirit
Geez, you're a helpful one, aren't you?

Okay, revised list (I'll just order from allelectronics once I have confirmation I'm good ... Rat Shack here is teh sux):

SPST N.O. MOMENTARY PUSHBUTTON -> OK
5 VDC 1 AMP SWITCHING POWER SUPPLY -> OK
10 OHM 1/4 WATT -> 10K Ohm 1/4W
112 OHM 3 WATT SAND -> whatfor do you need this one?
10K LINEAR PC MOUNT POT -> OK
500 OHM SQ. TRIM POT -> 500 ohm is OK but what means SQ.?
0.1UF DIP CAPACITOR -> OK
36 PIN FEMALE CONNECTOR, PC MOUNT -> not PC (Printed Circuit) mount, but solder version...
RJ-45 CORD COUPLER, STRAIGHT THROUGH FOR DATA
6' CABLE WITH RJ-45 CONNECTORS -> I would remove the RJ connector from the PSU and replace it by suitable connectors (male for the cable, female chassis to mount on your CD assembly.
GMA FUSE HOLDER, PC MOUNT -> OK
1/2 AMP 3AG FUSE -> OK
SOLDERABLE PERF BOARD -> OK

Think that'll do the trick? I assume I'll use the same pinout on the centronix connector, just moving the other end to the appropriate pin, and that this allows me to use a printer cable, right?

edit: thinking 16 gauge wire throughout ... the wire just slides into the holes of the centronix conn, right?

See my remarks in your quote.

To do the conversion from DB25 to Centronics, use my schematic and connect the right signals from the LCD to the right signals (and pin numbers) on the Centronics female connector.

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[Turbokeu]

About Radio Shack (they were called "Tandy" in Europe), I sympathise...
They went bankrupt ten or fifteen years ago in Europe.

CD

[airspirit]

That was a 12 OHM 3W resistor ... I don't know WHAT happened during that copy, hehe. I didn't catch the 10 OHM instead of 10K Ohm ... I'll fix that with them now.

I wanted the PC mount version of the centronix so I could mount that seperately ... I have a reason there so ....

The 6' RJ45 cable is to go from the coupler to board (it'll be trimmed down to wires). This way I can retain the RJ45 connector on the power plug for ease of disassembly.

SQ means "square" in this instance.

Whew ... I'm glad I didn't screw up TOO bad, hehe ... calling to fix that resistor error now. Thanks!

[airspirit]

So, something like this???

edit: which side has pin 1 on the connector? Is it the long side or the short side?

edit#2: did you use every other line in that IDE cable starting with line 1 inclusive? If so, why are the last few all cut off? That looks like an elegant solution, and I think I might go the same way.

[Turbokeu]

Originally posted by airspirit
So, something like this???

edit: which side has pin 1 on the connector? Is it the long side or the short side?

edit#2: did you use every other line in that IDE cable starting with line 1 inclusive? If so, why are the last few all cut off? That looks like an elegant solution, and I think I might go the same way.

1. Seems OK. Be sure the node between the upper side of S1, C1 and the right side of the 10K is connected all together to pin 9 (RST) of the LCD.

2. See my schematic earlier in my thread, there is a drawing of the Centronics connector.

3. Yes, all the uneven (1,3,5,....39) pins on the 40 pin IDE cable correspond to the lower row of 20 pins.
In my case I didn't need the last wire (pin 20 on my LCD is not connected)

4. Don't focus too much on the 12 Ohm resistor for now, there's a great chance you will need a different value for your BL (we can recalculate it when we know the exact current needs).

Three Watt for that resistor is WAY too much, in the case of my BL the dissipated power by the 12 Ohm resistor at 120mA is:
0.12²*12 = 0.17W.
Theoretically a 0.25W resistor could do the job, but the 0.17W is too close to the maximum dissipation of it (heat!).
That's why I opted for a 1Watt resistor.

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[airspirit]

From what I see in your pictures, pin 1 is (from the back) at the upper left (on the long side). Is this correct?

I don't think that overkill resistor will hurt anything ... I couldn't find a 1W so I went with the next larger size.

[Turbokeu]

Originally posted by airspirit
From what I see in your pictures, pin 1 is (from the back) at the upper left (on the long side). Is this correct?

I don't think that overkill resistor will hurt anything ... I couldn't find a 1W so I went with the next larger size.

Yes... Sorry, I thought I posted the schematic earlier in my thread...
Here it comes:


In PDF format

The PCB layout:


The component layout:


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