For the contrast line, you don't need any driver between your PIC and the LCD, a simple resistor in serie will do the job.... let's say in a range of 500 ohms - 2K.
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For the contrast line, you don't need any driver between your PIC and the LCD, a simple resistor in serie will do the job.... let's say in a range of 500 ohms - 2K.
Steve
It's not a bug, it's a random feature.
There's no problem, only learning opportunities.
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Salut Steve! Donne-moi de tes nouvelles de ton voyage.
How will you adjust the contrast using just a resistor?
I wanted it so that both the contrast and backlight could be adjusted from 4 UP/DOWN buttons. Using transistors and HPWM was the cheapest way I could come up with. I now have a range of 256 steps for both controls.
Robert
My Creality Ender 3 S1 Plus is a giant paperweight that can't even be used as a boat anchor, cause I'd be fined for polluting our waterways with electronic devices.
Not as dumb as yesterday, but stupider than tomorrow!
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It will work the same way for contrast. You must keep your transistor for the backlight. For contrast, use HPWM and a in-serie resistor from your PIC to your LCD VO line. If this input don't need negative voltage, i have to work AS IS. Maybe you'll need to revert the values (0-255 to 255-0) but that's not a big deal.
Steve
It's not a bug, it's a random feature.
There's no problem, only learning opportunities.
|
I used a 25K pot at first to get the contrast working:
- Vss at one end with 0V.
- Vout at the other end with -30V (built-in negative voltage).
- V0 at the wiper.
For a good contrast, the V0 wiper varied from -20V to -24V, with -22V for a good setting.
Robert
My Creality Ender 3 S1 Plus is a giant paperweight that can't even be used as a boat anchor, cause I'd be fined for polluting our waterways with electronic devices.
Not as dumb as yesterday, but stupider than tomorrow!
|
DOH! sorry... always read the Datasheet first, always read the schematic correctly too (Vout) Tabarnak!
Where's the whip?
Steve
It's not a bug, it's a random feature.
There's no problem, only learning opportunities.
|
maybe another solution... maybe, if not, broke my legs... again
try it first. Place a 10K resistor between Vout and VO, on Vo place a 1K resistor in serie. Now send the other resistor end to 5 Volt. What happen with the contrast?
If i'm not dumb it should do something. If so, in serie with the other 1K resistor, place a diode in serie. Anode to PIC, cathode to resistor end. Is it working? I have some doubt on that so far... -voltage against 0V and 5 Volt+diode plah plah. I really need to return on a bench... feel rusty here!
Last edited by mister_e; - 29th May 2006 at 15:19.
Steve
It's not a bug, it's a random feature.
There's no problem, only learning opportunities.
|
$99 USD per LCD.
I can't afford to do magic shows with these suckers.
Robert
My Creality Ender 3 S1 Plus is a giant paperweight that can't even be used as a boat anchor, cause I'd be fined for polluting our waterways with electronic devices.
Not as dumb as yesterday, but stupider than tomorrow!
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