scott@alfter.diespammersdie.us wrote:
Shaun Buzza <nospam.Shaun.Buzza@f110.n229.z1.fidonet.org> wrote:
I saw a youtube video about a 3D printer.
The video stated it was using an addon Pi to run the 3D printer.
Why the addon ? What is the Pi doing ?
Details please.
I would assume that the Pi is literally controlling the printer's motors,
based on the data being sent to it, in order to print whatever it is that
is being printed. But that may not be accurate, without seeing it for myself.
Could you provide a link to this video?
It's more likely that it's streaming gcode to the printer, and maybe running a camera, with something like OctoPrint. Motion control in a 3D printer is
a real-time task for which the Raspberry Pi is ill-suited. You'll almost always find another board somewhere on the printer that controls the motors and heaters; it could have anything from some of the slower speed grades of ARM-compatible microcontrollers (topping out under 200 MHz) on down to 8-bit AVRs at 16 MHz.
Well a microcontroller running Linux would be ill-suited also. It's
just that people allways expect a Pi to be running Linux and a
microntroller to be running no OS at all. While the Linux options
for microcontrollers aren't always that great, there are a
multitude a bare-metal environments available for the Pi.
Besides that, the PrintPi project uses the DMA hardware of the Pi
to achieve the required timing precision even when running Linux.
The GPU is also able to be programmed, thereby operating as a
separate processor within the Pi itself, able to run real-time
software like a microntroller (and be reprogrammed at run-time).
The only trouble with these latter options is that there is little
official documentation, and even less example code. Unless you have
access to the proprietary Broadcom SDKs perhaps. So that makes it
hard for open-source developers designing these things, who
generally choose to use a separate microcontroller instead.
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