Earlier on this thread I answered this question. Essentially you can have a second thread interrupt the blocked thread to unblock it. A TimerTask is a convenient way to achieve this. You can wrap the whole process in a method that would look pretty much like the interface you purposed. On Apr 29, 2014 2:53 PM, "Duane DeSieno" <[email protected]> wrote:
> I encountered a small problem. > In the case of a hardware or wiring problem with the PING, this code that > works will hang at the getDuration call. > Also, I noticed that a 20ms sleep works and a 10ms sleep does not with > working hardware. > > So my question is, can you give us a way to limit the time for the > getDuration(). > For example we know that the ping is only good to about 3 meters or > 17.74ms. > If we had a call like getDuration(msLimit), we could make the call > getDuration(20) and know that it will return after 20ms. > > I had an intermittent power lead to the PING and my whole robot stopped. > > Thanks > Duane > > > On Sunday, April 27, 2014 8:24:19 PM UTC-7, Ytai wrote: >> >> Cool. If you can create a nice class for using the PING (where the ctor >> gets a IOIO and two pin numbers, and there's a getDistance() method) and >> share it on this forum, it would be a decent return for our efforts :) As a >> side note, since you're doing the open-close trick, you might as well use a >> single pin and open-close the digital output as well and not need the >> driver chip, so you can even further simplify both your code and your >> circuit. >> >> >> On Sun, Apr 27, 2014 at 8:19 PM, Vic Wintriss <[email protected]>wrote: >> >>> I finally got it to work using your last suggestion. This code works >>> that you recommended works perfectly. Thanks so much for sticking with us. >>> We've got 30 or 40 kids using this code at the International Autonomous >>> Robot Competition (iARoC 2014) coming up at the end of June. Check out >>> iaroc.org. >>> >>> triggerHigh(); >>> in = openPulseInput(); >>> sleep(20ms); // wait until the pulse input module is ready for a pulse. >>> triggerLow(); // kick off a measurement (falling edge does not trigger >>> the pulse input) >>> duration = in.getDuration(); >>> in.close(); >>> return duration; >>> >>> On Sunday, April 27, 2014 11:36:53 AM UTC-7, Ytai wrote: >>> >>>> Let me shed some light on the internals of PulseInput: >>>> >>>> - A timer is running on the IOIO set to 200Hz (5ms). >>>> - As soon as the pulse input module is opened, and every time after >>>> a pulse is captured the module will be put in the "ready" state. >>>> - Every time the 200Hz timer triggers, each "ready" module will be >>>> activated, i.e. put in a state where it is waiting for a new pulse. >>>> - Once activated, the module will wait forever (or until closed) >>>> for a pulse, then measure its duration, then sends the result to the >>>> Android. >>>> - So this means that effectively no matter what the actual pulse >>>> rate is, you will never get more than 200 reports per second. This has >>>> been >>>> done on purpose to prevent a high frequency pulse train from saturating >>>> the >>>> connection between the IOIO and the Android. This also means that there >>>> is >>>> a potential "dead time" of up to 5ms after opening or between pulses, >>>> during which a pulse would not be detected. >>>> - On the Android side, every pulse report finds its way to your >>>> PulseInput object. You can then read it in one of three ways: >>>> - getDuration() will return the last report. It will generally >>>> not block, then only exception is until the first report arrives. >>>> - getDurationSync() will always block until a new report comes >>>> in, then return it. So you can be sure that the report is new. >>>> - getDurationBuffered() pulls pulses one by one from a queue. >>>> When the queue becomes empty it behave like getDurationSync(), i.e. >>>> waits >>>> until a new report comes in. >>>> >>>> The Arduino approach cannot be directly applied to the IOIO API, since >>>> you have to take into account that because of the communication between the >>>> Android and the IOIO, much of the IOIO API has been designed to be >>>> asynchronous in nature. If you were to bake the PING driver directly into >>>> the IOIO firmware, you can use a similar approach to Arduino's (although >>>> you'd probably want to implement it in a non-blocking way, since the IOIO >>>> allows everything to be used concurrently). The reason why I have not done >>>> that is because I tried to focus on generic use-cases rather than on one >>>> peculiar sensor interface. >>>> >>>> >>>> >>>> On Sun, Apr 27, 2014 at 10:57 AM, Duane DeSieno <[email protected]>wrote: >>>> >>>>> My confusion is maybe over the way getDuration works. >>>>> Does it delay 5ms before looking for the pulse or does it look >>>>> immediately? >>>>> I put 555 timer on the input pin and set it up for 3.15hz and 25.4% >>>>> duty cycle or an 80.6ms pulse every 317.4ms. >>>>> I called getDuration roughly every 100ms. It did not block and >>>>> returned the same value several times before the next pulse occurred(not >>>>> what I expected). >>>>> >>>>> Looked at the Arduino approach to using the PING and they use just one >>>>> pin, changing from output after sending a pulse to ping to an input for >>>>> their get duration call. >>>>> Since they don't impose a 5ms delay, they get the duration of the >>>>> return pulse. >>>>> >>>>> Thanks for you help on this. >>>>> >>>>> Duane >>>>> >>>>> >>>>> >>>>> >>>>> -- >>>>> You received this message because you are subscribed to the Google >>>>> Groups "ioio-users" group. >>>>> To unsubscribe from this group and stop receiving emails from it, send >>>>> an email to [email protected]. >>>>> To post to this group, send email to [email protected]. >>>>> >>>>> Visit this group at http://groups.google.com/group/ioio-users. >>>>> For more options, visit https://groups.google.com/d/optout. >>>>> >>>> >>>> -- >>> You received this message because you are subscribed to the Google >>> Groups "ioio-users" group. >>> To unsubscribe from this group and stop receiving emails from it, send >>> an email to [email protected]. >>> To post to this group, send email to [email protected]. >>> Visit this group at http://groups.google.com/group/ioio-users. >>> For more options, visit https://groups.google.com/d/optout. >>> >> >> -- > You received this message because you are subscribed to the Google Groups > "ioio-users" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To post to this group, send email to [email protected]. > Visit this group at http://groups.google.com/group/ioio-users. > For more options, visit https://groups.google.com/d/optout. > -- You received this message because you are subscribed to the Google Groups "ioio-users" group. 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