I imagine there's a reason you can't hook up a calculator LCD to a computer if you built a controller, but could someone inform me of why? I haven't found any answers on the interent, and I have limited electronics knowledge.
your right but for the wrong reasions really.. you COULD hook up the Calc LCD if you HAD a controler. however it's eather the controllers cost 400$ or you/we can't build them.
Those shouldn't be a problem at all to hook up. As long as you can write software for it. i remember someone made a CPU meter from 2 7sec LED displays. I guess you could use some of the same methods. I can't remember where i saw it, though.
No, you can't Smilodon: LCDs are very different to LEDs. They need a specially regulated AC input. You might be able to hack a different chip to work with the LCD, but using a PIC/plain logic will probably be a bit tricky. ch424
of course you'll need a driver chip for the LCD itself, but those come in many versions and prizes. Shouldn't be too expensive or advanced.
It would be quite easy if you went about it a different way. All of the buttons on a calculator are multiplexed - you need at most 5 wires. Hook these up to a pic, and write some clever code (or even resort to 1+1+1... etc.) I've tried it and its not very hard. Most calculators can handle very fast inputs, so you don't notice any flickering.
He's got a pretty good point, especially if you just want numbers, just have the computer mash the clear button, then send the number you want displayed.
"They need a specially regulated AC input" You mean theres an inverter in every calculator/PDA ive ever owned?
LCDs, I guess maybe now the cheap display ones, are usually driven by a low frequency square wave that is 180 degrees out of phase with the data in signal per segment. Ex. 10101010 <-Backplane 01010101 <-Input to a segment that will show 10101010 <-Input to a segment that will not show
yes, LCDs need AC to operate, depending on the kind, it can be very low frequecy I believe that on some text LCDs the frequency can be like .5hz (yes, 2 seconds per cycle) I forget exactly how it works now, I think on the text displays, the bias followed the AC waveform, the signals for each pixel were opposite if they were on, and in phase if they were off, or something to that effect. Doesnt have to be a nice sinewave AC btw, I think squarewave is ok, but I think that all of that would make constructing your own driver circuit... interesting. EDIT: haha Xiachunyi beat me
I have many LCD 7-segment displays from calculators. I remember years ago, when I was stupid, I took a 7-segment LCD calculator display and attached a 1.5v cell to random contacts until I got a few segments to 'light up'. I then went and did something else to occupy myself. I don't know if I damaged it or anything, I didn't see any smoke so... Sputnik
the ATmega169 has a built-in LCD controller. you will have to write some firmware for it, but it shouldnt be too dificult.
