Arduino - is it really needed?

Hi all, I'm new to this forum.

First of all, I love this project, and this community. I read the forums and your blogs regularly and I love to see where it goes.

Well, that's not the topic so let's go to the question;
Is the Arduino really needed? The RepRap is connected to a computer which transfers the "blueprints" to the Arduino which in turn controls the printer. Why not use parallel ports? It should be enough for the amount of data needed to control the motors and the printer, shouldn't it?

So what are the pros and cons of using Arduino and parallel ports? Using parallel ports could make the RepRap a lot cheaper.

I just want to know your reasons!

Kthxbye,
Boman

Couple of reasons most people don't want to use parallel ports:

Most modern computers, especially laptops, don't have parallel ports. If you have to buy a usb-paraller converter, it rather defeats the point.

Using a microcontroller means that printing without a pc is just a firmware upgrade and a sd card away. With a parallel port you simply have to have a pc.

With parallel ports, there is an upper limit on the number of controllable pins, about 12-ish. A microcontroller is very scalable, just get one with more pins/use a port expander, while you're stuck with a fixed amount with a parallel port.

This is more of a guess, but there may be issues with very low latency control of parallel ports, non-standard interfaces and the like. Usb in a nice work-anywhere standard, and provides a usable amount of power.

Boman, you'll want to take a look at:
[reprap.org]
[forums.reprap.org]


I suggest picking up a used 586 desktop pc for this.

Edited 2 time(s). Last edit at 05/04/2010 09:15PM by SebastienBailard.

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-Sebastien, RepRap.org library gnome.

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Remember, you're all RepRap developers (once you've joined the super-secret developer mailing list), and the wiki, RepRap.org, [reprap.org] is for everyone and everything!

Could it be done with just a PC? Sure.
The Parallel Port may only have about 14 usable pins for I/O but you
can multiplex them to get however many you need. Or you could even build your own IDE card to plug into your PC to do the control. That's how we did things in the 1970s, 1980s, and a bit into the 1990s.
It is easier to just use a microcontroller and it's a lot cheaper to replace a blown microcontroller than a motherboard when things go bad.

I just posted a link in another thread "dumb electronics question" perhaps some of you electronics guys could take a look and see if it would overcome the timing issues. The usb board you need is very cheap and so are the extra chips.

there are ways of doing just that if you look around just look at cnc controlers most that i have seen are very much over kill but a person would if he really wanted too.

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[mike-mack.blogspot.com]

The advantage of Arduino is that it can do ADC Analog to Digital Conversion that is needed for regulating the temperature of plastic in the extruder. i.e. read the thermocouple

If you use a computer it needs really to support real time processing. Also parallel ports are a dieing breed.

You can do 3d printing with EMC2 on a PC but it still needs to communicate with an Arduino ( Via serial interface ) to control the temperature.

Edited 1 time(s). Last edit at 05/12/2010 04:00PM by KeithSloan.

You could just buy an off the shelf PID controller to controll the temprature of the extruder and another one for a heated print bed.

This would mean you just need to wait till everything is up to temprature befor starting the CNC process.

You could use the PiD to indicate this and feed the PID outputs into the CNC control system as ready to print/extrude signals Spindle up to speed input could be re-assigned to do this.

This gives flexibilty on temprature control of extrusion manual setting of temprature on the PiD controller they have a Led temprature display.

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Bodge It [reprap.org]
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