Thanks for your reply. The circuit looks great I’ll probably use it at some point but this won’t work with the LCD driver.
So let’s just ignore all other pins of the LCD and focus on 2 of them.
The ground pin and the pin of the segment I need that state of (on/off).
So the way the DC microcontroller drivers them is they apply a square wave form to the ground pin. If you want the segment to be ON you have to drive it with the inverted wave form of the ground pin.
But if you wanted that segment to be OFF you have to drive it with the same wave form as the ground pin.
Both pins the ground and the segment pin are always driven no matter if the sedment is displayed or not the difference is only in the wave form.
For this reason when it’s measured with a multimeter there is always a voltage in all 19 pins of the LCD display regardless of it displaying anything or not.
And indeed when I measure the 19 pins the multimeter shows 1.5v on every single one even though only the battery symbol is displayed.
As I said I’m a beginner and I know only so little about the topic.
I got this info from this video:
https://youtu.be/ZP0KxZl5N2oYesterday I was thinking about a method but I don’t know if that would work.
So lets call ground pin and the segment pin A and B.
I want to connect A to the gate of transistorA. The source would be connected to 3v via a pull up resistor.
Drain would be connected to source of transistorB and drain of the second one would be connected to ground. And of course B would be connected to gate of transistorB.
So I just connected 2 transistors in series and if both gates pulled high then the 3v pulled voltage on the source would be grounded through the 2 transistors.
If the segment is on on the LCD then the g signals from A and B would never occur in the same time so the 3v pulled up signal never goes to ground.
If the segment is off then A and B would have the same square wave meaning they would open and close the 2 transistors in the same time and my pull up signal would get grounded every time the wave form is high.
May be there would be a measurable difference there. But I’m really not sure.
As I said I’m a beginner beginner. No electronic background. Just trying to tinker.
Any comments would be appreciated.