Hello, I’m looking around for documentation on this LCD-08498? I can’t seem to find much on how to actually interface it. The controller manual is great, however, the physical layout still leaves me clueless. I’ve never worked with a CSTN/STN LCD before, so if it’s a standard – sorry for my ignorance. I’m not certain what the RS pin is, but it couldn’t be reset, considering there is also a /RST pin. Any idea? Also, I’m still not sure what voltage is required on LED+/-, is it 13V? It also doesn’t say how much current it needs to draw, etc. Any ideas? I’d like to use the LCD on my next project but I don’t even know what kind of connector it is using. 
Ok, I’m guessing I require an FPC 0.5mm connector. I’m still not certain about what voltage I require on the LED+? 13.8V doesn’t sound right for an LED. I’m guessing LCD Driver voltage is 13.8V, and then that’s probably internal to the controller? Getting there… :lol:
I know its Christmas, so I’m not really expecting too many replies asap, just wondering if anyone else has wondered?
[EDIT:] Here’s hoping I’m just being a nub, could I just use any voltage from 2-5V on the LED with a protection resistor, like I would with a ‘normal’ LED?
Then lastly, I’m guessing the RS pin is register select pin AKA A0 on the controller documentation. Also, what kind of refresh rate am I looking at? I’d like to get 30+hz framerate. Thankfully it’s parallel
Hi there. LED backlights in LCD’s generally consist of the LED’s arranged in series. By doing it that way you get a fairly consistant brightness because they all use exactly the same current. Driving these require a constant current source (rather that the constant voltage of a battery or DC adapter). These are fairly easy to make using a normal 3 terminal Linear Regulator like the LM317 but you will need to do a bit of research to find a circuit as I don’t have one handy.
The problem with LCD backlights like this though are that sometimes you need fairly high voltages. Take the Sony PSP LCD for example, these have 7 white LED’s arranged in series with a (potential) maximum drop of 30V across them and drawing 15-20mA. This can be a real problem when your main circuit runs from 3.3V or 5V in which case you will need some sort of Boost Converter to power it. An axample of this is the Zetex ZCLD1937 which takes an input DC voltage of between 2.5 and 5V while producing a selectable constant current output at anywhere up to 30V. Of course, if you have a 33V+ DC power source handy you could power the LED using the (simpler) LM317 circuit mentioned above but as this is a rare scenario I would consider the ZCLD1937 instead
Thank you for the response!
So I basically just have to play around with the voltage until I get something?
Sparkfun mod’s – Do you have a better datasheet for this LCD? I’d honestly like to NOT break it. 
So I basically just have to play around with the voltage until I get something?
That’s one potential solution. As long as you feed this voltage through the current source first the current source will make sure that the backlight gets exactly what voltage it needs and no more (provided you are within specs). So, for example, say you have a 0-40V bench lab supply at home. If you hook it up to the CS and start increasing the voltage, eventually the CS will have a high enough voltage to supply what the backlight requires and it will light
The other solution you might consider, if you have a multimeter with a diode test mode, is to use it to determine the forward voltage drop across the backlight’s LED chain
That’s the best I can suggest unfortunately
Do you have a better datasheet for this LCD? I’d honestly like to NOT break it
I wish I did, I’d like to play with the LCD myself. I’ve been trying to look around for an example of someone who’s already used this LCD so I can have a look at their schematic but so far I haven’t had any luck.
Thank you for your help, HumanBean.
That makes a ton of sense now. I’ll have to be a man and risk breaking it, for science!.
I also recently got hold of one of these displays and am about to try it out. So, if you don’t mind, please keep posting any new findings you have; the fewer displays in total we destroy, the better
Apparently user seulater (from this forum) made it work, though he doesn’t seem to be too happy with it from the review. I wonder if he could post some notes about what he did. Not sure if he’s still around this forum or how to contact him really.
Well, I tried the backlight.
I used a 12V current limited source. There appear to be only two white LEDs in series in there. It seems to need at least 8.5V for full brightness at a given current. It’s goes completely off somewhere between 7 and 8V. Wasn’t measuring too accurately as it doesn’t matter too much - it’s well above the 3.7 Li-Ion battery I have, so a constant current boost converter is necessary.
Maximum current I tried was around 25mA, no problems. That’s on the low side, but the backlight appears about as bright as it is on my Nokia 6100. That’s with all pixels black though, so hard to tell. The rest of the testing will have to wait until my breakout board arrives though.
And now I have a problem - no connector. Digikey has one that may work (609-1182-1-ND), but I can’t order from Digikey - it would cost me $1.48 for the connector plus around $80 (!) for shipping to NZ. ‘Local’ distributors (Farnell and RS) do not stock any 0.8mm pitch FFC connectors at all. Sparkfun also don’t seem to have any; if they did, all would be well: amazingly enough, they are willing to ship to NZ by ordinary air mail at $3.50. I can’t express how much I like that.
Where did you get your connectors for this display?
And now I have a problem - no connector. Digikey has one that may work (609-1182-1-ND), but I can’t order from Digikey - it would cost me $1.48 for the connector plus around $80 (!) for shipping to NZ
I buy from DigiKey every 3-4 months so I know how you feel. It’s a great supplier but the only way to mitigate the large postage costs it to buy $200+ dollars worth of parts. It makes me fell a little better… a little
‘Local’ distributors (Farnell and RS) do not stock any 0.8mm pitch FFC connectors at all
According to the datasheet, the LCD uses a 0.5mm pitch FFC so you could be in luck there. Give it another go
I have mailed SparkFun twice now asking them to stock both the 4 pin backlight connector for the PSP LCD and the 54 pin one for the 3.5 inch LCD and received replies about breakout boards both times. It’s very frustrating but maybe if enough people email them about it they will start stocking them
I wish you were right...According to the datasheet, the LCD uses a 0.5mm pitch FFC so you could be in luck there. Give it another go
This is the datasheet I was reading: http://www.sparkfun.com/datasheets/LCD/ … 015-01.pdf
I checked it again and I can see where the confusion could be coming from: the pin width is 0.5, but the pin spacing/pitch is 0.8 (C1 on the drawing - it says something like P0.8*26=20.80±0.05). And indeed, when measured, the FFC is definitely 0.8 pitch.
To make things worse, it also has some sort of mounting holes on the sides of the connector area. Those can be cut off though, so not worried too much.
Ah yes, you’re spot on right. I thought we were talking about the 3.5" 320x240 LCD :oops: