Hi Andre,
When I tried to run your code, it didn't compile for me:
user=> (defn infinite [f seconds] (future (loop [] (f)
(Thread/sleep (* seconds 1000)) (recur))))
#'user/infinite
user=> (infinite (printf "\nlooping") 10)
looping
NullPointerException user/infinite/fn--2267 (NO_SOURCE_FILE:1)
user=>
When you call infinite, (printf "\nlooping") gets evaluated, produces
expected side-effect, returns nil. This happens before infinite is
executed. Within infinite (f) is effectively (nil).
Also it seems you want to block. But because your loop is wrapped with a
future, it runs in a separate thread. So it doesn't block. After infinite
is called, the program exits. Possibly before (f) is executed.
On Fri, Jun 13, 2014 at 4:33 AM, Andre Perez <andreope...@gmail.com> wrote:
> Hi everyone, I just started trying to play with a raspberry pi for a
> variety of reasons, and given that java runs on it, I decided to use this
> as an opportunity to learn clojure. I'm playing with a blinkIo example
> which looks like this:
>
> public class BlinkGpioExample {
>
>
> public static void main(String[] args) throws InterruptedException {
>
>
> System.out.println("<--Pi4J--> GPIO Blink Example ... started.");
>
>
> // create gpio controller
>
> final GpioController gpio = GpioFactory.getInstance();
>
>
> // provision gpio pin #01 & #03 as an output pins and blink
>
> final GpioPinDigitalOutput resevoirPumpLine = gpio
>
> .provisionDigitalOutputPin(RaspiPin.GPIO_01);
>
> final GpioPinDigitalOutput troughFillLine = gpio
>
> .provisionDigitalOutputPin(RaspiPin.GPIO_03);
>
>
> // provision gpio pin #02 as an input pin with its internal pull down
>
> // resistor enabled
>
> final GpioPinDigitalInput resevoirSwitch = gpio.provisionDigitalInputPin(
>
> RaspiPin.GPIO_14, "Resevoir Switch", PinPullResistance.PULL_DOWN);
>
> final GpioPinDigitalInput trougSwitch = gpio.provisionDigitalInputPin(
>
> RaspiPin.GPIO_13, "Trough Switch", PinPullResistance.PULL_DOWN);
>
> resevoirSwitch.setShutdownOptions(true);
>
> // create and register gpio pin listener
>
> resevoirSwitch.addListener(new GpioPinListenerDigital() {
>
> @Override
>
> public void handleGpioPinDigitalStateChangeEvent(
>
> GpioPinDigitalStateChangeEvent event) {
>
> // when button is pressed, speed up the blink rate on LED #2
>
> if (event.getState().isHigh()) {
>
> System.out.println(event.getPin().getName() + " do nothing");
>
> } else {
>
> resevoirPumpLine.blink(1000);
>
> }
>
> }
>
> });
>
>
> trougSwitch.addListener(new GpioPinListenerDigital() {
>
>
> @Override
>
> public void handleGpioPinDigitalStateChangeEvent(
>
> GpioPinDigitalStateChangeEvent event) {
>
> if (event.getState().isHigh()) {
>
> System.out.println(event.getPin().getName() + " do nothing");
>
> } else {
>
> //stick value into a flat file or in mem database;
>
> troughFillLine.blink(1000);
>
> }
>
>
> }
>
> });
>
>
> System.out
>
> .println(" ... the LED will continue blinking until the program is
> terminated.");
>
> System.out.println(" ... PRESS <CTRL-C> TO STOP THE PROGRAM.");
>
>
> // keep program running until user aborts (CTRL-C)
>
> for (;;) {
>
> Thread.sleep(500);
>
> }
>
>
> }
>
> }
>
>
>
> Since I am quite new to clojure, i attempted to do a straight port to
> clojure (as opposed to writing the blinkio in a more functional manner) and
> came up with :
>
> (def factory (GpioFactory/getInstance) )
>
>
> (def pumpOutput (.provisionDigitalOutputPin factory RaspiPin/GPIO_01))
>
> (def troughOutput (.provisionDigitalOutputPin factory RaspiPin/GPIO_03))
>
>
>
> (def pumpInput (.provisionDigitalInputPin factory RaspiPin/GPIO_13
> "troughSwitch" PinPullResistance/PULL_DOWN))
>
> (def resevoirInput (.provisionDigitalInputPin factory RaspiPin/GPIO_14
> "resevoirSwitch" PinPullResistance/PULL_DOWN))
>
>
>
> (def resevoirListener (reify
> com.pi4j.io.gpio.event.GpioPinListenerDigital (
> handleGpioPinDigitalStateChangeEvent [this event] (printf "resevoir here")
> )))
>
> (.addListener resevoirInput [
> ^com.pi4j.io.gpio.event.GpioPinListenerDigital resevoirListener] )
>
>
> (def troughListener (reify com.pi4j.io.gpio.event.GpioPinListenerDigital (
> handleGpioPinDigitalStateChangeEvent [this event] (printf "trough here")))
> )
>
> (.addListener resevoirInput [
> ^com.pi4j.io.gpio.event.GpioPinListenerDigital troughListener] )
>
>
> (defn infinite [f seconds] (future (loop [] (f) (
> Thread/sleep (* seconds 1000)) (recur))))
>
>
> (infinite (printf "\nlooping") 10)
>
>
> **********
>
> My question: This compiles, and runs, but doesn't actually do anything
> when I manipulate the PI io. I am thinking I have to do something
> regarding defining my inputIOs as atoms, but I'm still trying to get my
> head wrapped around that concept. Could someone please point me in the
> right direction to get my (printf "trough /resevoir here") messages to
> display? Mind you that there isn't a problem with any of the wiring on the
> PI, it is verified in the java version of this program. I am just having
> trouble porting this code.
>
>
> Thanks for any help!
>
> Andre
>
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Kind Regards,
Atamert Ölçgen
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