GPIO pin control

[bluetape66]

Simple question how do you use the gpio pins to control something like a fan?
I was also wondering if you could put more then 3.3v through the pis pins, to control something like a large fan.

I have minimal knowledge in python and the more detailed explanation the better!

[jbeale]

The GPIO pins come directly from the SoC device on your Pi (the CPU+GPU chip). It is fixed at 3.3 V and low current, this is a logic-level signal, not a motor drive. You should not try to draw more than about 10 mA of current; most motors need much more than this. To drive a motor you want some additional circuitry that will work with higher currents and voltages.
Maybe something like this, can work with 12 V up to 2.5 A: http://www.piborg.com/picoborg

[bluetape66]

The GPIO pins come directly from the SoC device on your Pi (the CPU+GPU chip). It is fixed at 3.3 V and low current, this is a logic-level signal, not a motor drive. You should not try to draw more than about 10 mA of current; most motors need much more than this. To drive a motor you want some additional circuitry that will work with higher currents and voltages.
Maybe something like this, can work with 12 V up to 2.5 A: http://www.piborg.com/picoborg

WOW this is great! It might sound childish but I want to make the pi fly! Could you control the speed of all four motors from one data pin?

[jbeale]

Well, it is definitely possible to make a quadcopter using a R-Pi.
For example, http://www.youtube.com/watch?v=bVv83PGtmnM
More details: http://www.raspberrypi.org/phpBB3/viewt ... 46#p301745

[mahjongg]

No in principle the GPIO's are simple on/off ports, to control motor speed something more complex is needed.

It often done with "pulse with modulation" (PWM) which means that a constant stream of logic level pulses is created, where the width of the pulses can be varied, that is the length of the time the pulse is "high" can be varied, often when the high time is increased the low time is decreased just as much, so that the frequency of the pulse stream stays the same.



PWM is often used to control the angle of a servo motor, but it can also be used to control a motor driver/controller (IC). And it's quite easy to convert a PWM signal into an analog signal (that can control how much current is fed to a motor)

The some of the PI's GPIO pins can do more than just switching on or off, for example some can send/receive serial data, to/from a RS232 driver. One of the GPIO's has extra hardware, so that it can act like a dedicated PWM generator, but just one GPIO pin knows how to do this trick.

However, creating a PWM signal can also be done in software, and someone already wrote software to create not one, but many PWM signals!

[bluetape66]

Well this is all great on the hardware side but what about software?

[keybeeper]

Well this is all great on the hardware side but what about software?

You may find some help here

http://code.google.com/p/raspberry-gpio ... i/Examples