A non blocking delay

RE: A non blocking delay

celem — Tue, 28 Jun 2016 01:14:04 GMT

I altered Andy Clark's solution to better suit my needs. While I kept the Timeout member, I am not using it. I modified Delay() so that it stands alone and only executes the code after the timer expires. Here is what I am using. Note, all three files are concatenated together for this comment.

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RE: A non blocking delay

celem — Mon, 27 Jun 2016 20:34:11 GMT

Andy Clark's solution is concise and makes for readable source - but behaves as a do {..code..}while loop where the 'code' will execute one and the delay only applies to subsequent executions of Timeout(). Using the example code:

[embed:dc8ab71f-3b98-42d9-b0f6-e21e02a0f8e2:3ef06e6b-9b7d-4651-b12d-db8be7f5e991:type=c_cpp&text=void+loop%28%29+%7B%0A++if+%28d.Timeout%28%29%29+%7B++++%2F%2F+always+true+on+first+call%0A++++digitalWrite%28led%2C+ledstate%29%3B%0A++++ledstate+%3D+ledstate+%3D%3D+LOW+%3F+HIGH+%3A+LOW%3B+%2F%2Ftoggle+state%0A++++d.Delay%281000%29%3B%0A++%7D]

d.Timeout returns (iTimeout < millis()). On the first invocation iTimeout is indeterminate but, unless millis() has turned over, probably less than millis() returns, so 'true' will be returned. Once d.Delay is called iTimeout will be set to millis() + 1000 so subsequent calls to d.Timeout will return 'false' until millis() increments above iTimeout.

This is useful where a do {..code..}while loop is called for, such as blinking the LED but not useful in a delay before executing situation, which is more like a blocking delay() would do. I haven't figured out how to do that yet - meanwhile Andy Clark's solution works for some situations.

RE: A non blocking delay

mcb1 — Tue, 10 Jun 2014 06:35:42 GMT

What about simply using the Millis() timer.

The example BlinkWithoutDelay (stupid name IMO) shows how to do it.

Use an unsigned long variable declaration and always subtract the lower number from the larger and the rollover works fine.

An example of its use as a debounce on a button

[embed:dc8ab71f-3b98-42d9-b0f6-e21e02a0f8e2:3ef06e6b-9b7d-4651-b12d-db8be7f5e991:type=c_cpp&text=++%2F%2F+Button+handling+variables%0A++boolean+ButtonState+%3D+HIGH%3B+++++++++++%2F%2F+records+the+Button+State%0A++unsigned+long+LastButtonCheck+%3D+0%3B++++%2F%2F+Time+the+Buttons+were+last+checked.%0A++unsigned+long+ButtonPressTime+%3D+0%3B++++%2F%2F+Time+the+last+button+was+pressed.%0A++int+ButtonCount+%3D+0%3B++++++++++++++++++%2F%2F+Button+counter]

[embed:dc8ab71f-3b98-42d9-b0f6-e21e02a0f8e2:3ef06e6b-9b7d-4651-b12d-db8be7f5e991:type=c_cpp&text=if+%28millis%28%29+-+LastButtonCheck+%3E+5%29++++++++++++++++++++%2F%2F+Reads+button+state+every+5mS+and+then+updates+button+counts%0A++++++%7B+++++++%0A++++++++ButtonState+%3D+digitalRead%28Pushbutton%29%3B%0A++++++++LastButtonCheck+%3D+millis%28%29%3B+%0A%0A++++++++if+%28ButtonState+%3D%3D+LOW%29%0A++++++++%7B%0A++++++++++ButtonCount+%2B%2B%3B+++++++++++++++++++++++++++++++++++++%2F%2F+Increment+the+Count+by+1%0A++++++++++if+%28ButtonCount+%3E+5%29+++++++++++++++++++++++++++++++%2F%2F+the+button+should+be+LOW+for+5x5mS+%3D+25mS%0A++++++++++%7B%0A++++++++++++%2F%2F+Button+has+been+pressed+for+longer+than+25mS+so+its+valid%0A++++++++++++ButtonPressTime+%3D+millis%28%29%3B+++++++++++++++++++++++%2F%2F+set+the+Button+press+timer%0A++++++++++++ButtonCount+%3D+0%3B%0A++++++++++++ProcessButton%28%29%3B++++++++++++++++++++++++++++++++++%2F%2F+Do+something+with+the+valid+button+press%0A++++++++++%7D%0A++++++++%7D%0A++++++++else++++++++++++++++++++++++++++++++++++++++++++++++++%2F%2F+Button+is+HIGH%0A++++++++%7B%0A++++++++++ButtonCount+%3D0%3B+++++++++++++++++++++++++++++++++++++%2F%2F+Reset+the+counter+as+the+button+has+been+released%0A++++++++%7D%0A++++++%7D]

mark

edit ... change the 100mS to 25mS in the comment on line 11

RE: A non blocking delay

Former Member — Mon, 09 Jun 2014 21:33:40 GMT

Hi,

This is a great class, thanks! I've got it working with a few examples, but am having trouble getting it working while iterating through a loop. Do you see any trouble with the syntax of my for-loop here?

[embed:dc8ab71f-3b98-42d9-b0f6-e21e02a0f8e2:3ef06e6b-9b7d-4651-b12d-db8be7f5e991:type=c_cpp&text=NonBlockDelay+ramp%3B%0A%0Avoid+loop%28%29+%7B%0A++++%2F%2F+The+goal+is+to+delay+writing+new+i+values+to+myPin%0A++++for+%28i%3D0%3B+i%3C256%3B+i%2B%2B%29+%7B%0A++++++++if+%28ramp.Timeout%28%29%29+%7B%0A++++++++++++analogWrite%28myPin%2C+i%29%3B%0A++++++++++++%2F%2FSerial.println%28i%29%3B%0A++++++++++++ramp.Delay%281000%29%3B%0A++++++++%7D%0A++++%7D%0A%7D]

Thanks for any insights -- this is really puzzling because, oddly enough, if I uncomment line 8, the delay somehow works. I'm at a loss.