I've been working on a braille-esque project for school lately and since I'm waiting on the microservos to arrive yo actually make a relieves surface, I've been using a led matrix to practice on displaying the characters.
I've been wondering if I could take my MAX7219 8x8 led matrix and divide it in parts that could be controlled separately, or if I would be better off going with a LCD text screen. The idea is to take the input of text, translate it to braille and make the leds turn on on 2x3 subgrids inside the bigger 8x8 grid.
I'd think the LED matrix would translate better to the relay setup than an LCD. Either way you'll have to devise a lookup table to store the patterns corresponding to each text character.
If you were thinking of printing dot patterns on the LCD display (assuming a generic 16x2/4 sample with HD44780 brain chip) know that you can only have eight custom characters at a time.
I'm not sure trying to get your braille to appear on LEDs or an LCD is worthwhile, since it is only for testing. You could spend a lot of effort on it that could be better spent on the translation part of the code.
I would simply use Serial Monitor for testing the output, displaying the braille as a series of * symbols for example.
If you decide to continue with the idea, a 16x2 character LCD could be used. 8 user defined characters would be enough, if each braille symbol occupies 2 character positions.
No not really.
Do you want the servos to move proportionally or just up or down?
How many servos do you envisage using?
Powering more than one servo from the 5V of an Arduino is problematic. Normally you will need to supply external power to drive them, and don't forget to make the grounds common.
You will also need some good supply decoupling to prevent the electrical noise from the servo motors from resetting the Arduino.
The idea is to get the servos in the standard six dots of braille and get them to move up and down according to the character they recieve, going fully up isn't a problem as long as they function.
By seeing the replies, I'd suppose using an LCD is more effective if not the only way to get what I want. I've already been working on the translation (I'm not using the "shortened" braille for now), but I want to start with the small and progress onto the big
Servos may not be the best choice to raise dots very little.
Possibly very short pieces of memory wire would make a more compact solution. That's one of a few alternates. I wanted to make braille calculators decades ago but lacked funds.
They are designed to be used as head positioning for a CD drive.
They are not entirely suitable because a stepping motor has no idea where they are on power up. However, when these reach their limit they simply click instead of getting stuck.
Also a stepping motor takes the maximum current when they are stationary.
How are you going to physically make something push up with those?
Using 60 for a start is a typical beginners approach, do not do this start with one.
I have some of these rescued from CD drives, and I can't see how they are going to be mechanically connected to push a surface. What is this surface anyway?
On the driver side you will need two H-bridge circuits for each motor, what are you going to use for that?
I measured the coil resistance and it came to 9.8Ω. So at 5V this will take half an amp each. Of course you don't drive them like this as they would over heat.
What this means is that you need what is known as a chopping regulated driver. This monitors the current and turns it off when it reaches a specified set limit. This is a fast process and can happen many thousand times a second. Regulator drivers for this are not cheap.
Here is a photograph showing the whole CD drive mechanism. The movement is transferred from the helix of the motor by the green spring loaded clip, to the rails that move the laser head. In fact it is this spring clip that causes the motor to click when it reaches either extreme limit of travel.
