Wiring a motor to the RPi?

What do I need?

I am told that I need some transitors. I have a 12v powerpack and 2 x12v motors. How do I set this up so that I don't blow-up the RPi and that I can control the motors through the GPIO?

I have a gertboard on the way but I would like to see if I can do it without it first.

I have little knowlegde about transitors and electronics but I do know how to build circuits.

wallarug over 13 years ago in reply to e14 Contributor

Thanks Ken,

I haven't got the H-bridge yet, but I will test when I get it.
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wallarug over 13 years ago in reply to e14 Contributor

There is no 5 volt supply on the ULN2003 (as far has I can see). Could you tell me the corresponding pin on the IC ULN2003?
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wallarug over 13 years ago in reply to e14 Contributor
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e14 Contributor over 13 years ago in reply to wallarug

You need to tie pins 4, 5, 12, and 13 to ground.
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wallarug over 13 years ago in reply to e14 Contributor

I know that. It was to much time to add to the diagram.
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wallarug over 13 years ago in reply to e14 Contributor

I have not yet tried the one PWM output on the Pi. I don't know if a PWM driver is ready or not.
An 8 but micro-controller normally has PWN hardware outputs.

Software pwm is where you turn the GPIO output off and on and increase the speed
by having it on a higher percentage of the time.
I need to know how PWM will work in the circuit. So the Raspberry Pi has ONE (1) PWM channel. Does this work in a pair or on a single wire tied to ground?

If I want to control the two motors individually then I will need a mircocontroller. Correct?
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wallarug over 13 years ago in reply to e14 Contributor

Ok. I just read this article: https://projects.drogon.net/raspberry-pi/wiringpi/software-pwm-library/ Which says this:
WiringPi includes a software-driven PWM handler capable of outputting a PWM signal on any of the Raspberry Pi’s GPIO pins.
Is this even possible?
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michaelkellett over 13 years ago in reply to wallarug

It's certainly possible - the article explains that it is limited because it is a software controlled PWM so can only do 100Hz with a minimum pulse width of 100uS for a range of 100:1. A modest micro might be expected to manage 40kHz, 1uS minimum pulse width and 256:1 range. Fancy micros and DSPs can do much better.
The software aaproach should be just about OK for lamp control but I'd be a bit cautious with motors - some will be OK but not all.

The RPi IO is pretty hopeless - the sodtware PWm is making the best of a bad job but it could well be OK for some things.

Michael Kellett
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yvanttt over 13 years ago

One option is to use the gertboard and drop in an atmega 328.

With this setup the PI will be the brain part and the arduino the muscle portion of the setup.
the Gertboard has already 2 motor interface on it.
And the arduino has 6 PWM build in.

It will then be easy for the PI to just send the PWM values to the arduino via the serial port or I2C as you wish.
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wallarug over 13 years ago in reply to yvanttt

48. Sep 27, 2012 4:37 PM (in response to Fergus Byrne)
Re: Wiring a motor to the RPi?
One option is to use the gertboard and drop in an atmega 328.

With this setup the PI will be the brain part and the arduino the muscle portion of the setup.
the Gertboard has already 2 motor interface on it.
And the arduino has 6 PWM build in.

It will then be easy for the PI to just send the PWM values to the arduino via the serial port or I2C as you wish.

The problem is: How do I do that?
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