Support for stepper motors added to Pi4J API

[Robert Savage]

I have added support for controlling GPIO based stepper motors to the Pi4J library.

Here are the API interfaces:

https://github.com/Pi4J/pi4j/blob/develop/pi4j-device/src/main/java/com/pi4j/component/motor/Motor.java

https://github.com/Pi4J/pi4j/blob/develop/pi4j-device/src/main/java/com/pi4j/component/motor/StepperMotor.java

See this article for complete details and example code:

http://www.savagehomeautomation.com/projects/raspberry-pi-stepper-motor-control-breakout-board.html

(Requires latest 0.0.5-SNAPSHOT version)

[Diego Medina]

Hi,

I'm using 0.0.5-SNAPSHOT from sonatype, but I get a compiler error saying

[error] .../src/main/scala/com/fmpwizard/gpio/Controller.scala:4: object component is not a member of package com.pi4j

[error] import com.pi4j.component.motor.impl.GpioStepperMotorComponent

[error]                 ^

which jar is the one that has components?

P.S. I'm using this library from scala, and the other GPIO examples work fine, like the one to turn an LED on and off.

Thanks

  Diego

[Robert Savage]

Hi Diego,

The "components" are currently located in the pi4j-device.jar.  

I think they will ultimately move into the core library, but they are just now getting API defined :-)   

Thanks, Robert

[Diego Medina]

awesome, thanks!

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Diego Medina
Lift/Scala Developer
di...@fmpwizard.com
http://www.fmpwizard.com

[Ryan White]

Hi Robert

Pi4J is excellent, and I'm planning on using it in a little x-y positioning system. I'm using a system outlined here: http://corexy.com/theory.html - which looks like it needs the two stepper motors to run at the same time. Not being a Java programmer, I can't figure out how to run two stepper motors at the same time. Is there sample code somewhere, or could you provide me with a snippet or link to documentation or something that would help me out?

Any and all info much appreciated!

Thanks
Ryan

[Robert Savage]

Hi Ryan,

Let me start off with saying that I'm certainly no expert when it comes to stepper motor control :-) 

I have not implemented anything complicated or precision based personally. 

For the conversation, I'll assume your stepper motors are controlled via PWM (Pulse Width Modulation).

(There are other type of motor control out there)

Unfortunately the Raspberry Pi only includes a single PWM pin.  

This means that for a high precision solution, you will need some external peripheral device to provide additional PWM support.

This board is one example: https://www.adafruit.com/product/815

This board includes the PCA9685 chip which provides 16 channels of PWM.

One of the community members (Christian Wehrli) contributed an Pi4J extension to support the PCA9685 chipset.

https://github.com/Pi4J/pi4j/blob/develop/pi4j-gpio-extension/src/main/java/com/pi4j/gpio/extension/pca/PCA9685GpioProvider.java

And here a a couple of code examples using this extension:

https://github.com/Pi4J/pi4j/blob/develop/pi4j-example/src/main/java/PCA9685GpioExample.java

https://github.com/Pi4J/pi4j/blob/develop/pi4j-example/src/main/java/PCA9685GpioServoExample.java

I hope this helps get you started :-)

Thanks, Robert

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