* you can have any number of case statements */įirst, put your major processing into functions. Volatile boolean expressionChanged = false I had to modify it a bit, so it might not work out of the box, but will give you the idea as to how. What I did was use my own delay function that checks if the expression has changed, and if so, immediately returns.īelow is my code. The problem, most of the time, is the use of delays. Most of the time this isn't a problem, because code normally runs pretty fast. You have, as recommended by Gerben's and Nick's answers. Just test whether the expression has changed inside every busy-wait loop (To prevent auto popups, set the delay to a large number of milliseconds. Using finite state machines (see for example the tutorials After a block-opening statement, the next line is indented by 4 spaces (in the. CTC timer interrupts are triggered when the counter reaches a specified value, stored in the compare match register. Each of the timers has a counter that is incremented on each tick of the timers clock. The Uno has three timers called timer0, timer1, and timer2. Obviously this could require a heavy refactoring of your code, probably Step 1: Prescalers and the Compare Match Register. Unless it's the last byte ofĪ complete message, in which case it would process the message. If a byte isĪvailable, it would buffer it and return. It would return immediately if no byte is available. A communication routine would not wait for complete messages.Is available, it would retrieve it, send a query to the next sensor It would return immediately if no reading is available. A routine reading sensors would not wait for them to respond. Preferred way of doing this would be to make sure no function ever What you intend, there certainly is a clean way of achieving the sameĮnd result: just make sure your switch statements return fast. In case of problems, debugging this may be harder than just testing theĮxpression inside every slow function you have.Īddendum: Although I am saying that there is no clean way of doing Carefully examine the generated assembly to convince myself it does.Warning: This is a (very dirty) hack that I have not tested. Interrupts are re-enabled not by the reti instruction but by longjmp() Have to enable them explicitly upon return from setjmp() Since we are skipping this exit sequence, we Notice that the normal exit sequence of an ISR (the reti instruction) Setjmp(env) // landing point from ISR exit Kind of like a goto statement that works across functions: #include Then, in the ISR, you restore that context with longjmp(). You save the current context with the setjmp() Here is an idea that may work: right before the switch statement, You asked 'How can I interrupt a delay() when a button is pressed' The short answer is that you cant. Simple solution to your problem is to replace delay() by the codeĪbove, and then change it so that it monitors the button instead ofĭoing nothing.It is certainly possible, although I do not think there is any clean To do nothing, you want it to monitor the “alarm stop” button. Send commands via the arduino serial console, D500 for 500µs delay, L100 for a 100µs long pulse. I have also tried changing the timer prescaler, but then the jitter is also scaled up in an unacceptable way. The problem here is the “do nothing” part. Since this example is interrupt-based, adding delay() statements do not really seem to work. Here is how you can apply this technique to your alarm() function: InĪ nutshell, you can think of delay() to be roughly equivalent to this: void naiveDelay(uint32_t ms) This approach is well described in the Blink without Way to avoid delays is to use instead the millis() function to control But you actually do not need them: the standard As outlined by ARK in his answer, interrupts could be used to This means, among other things, that it cannot be reactive to user That should most of the time be avoided for one simple reason: when theĪrduino is executing the delay() instruction, it does nothing but You can use millis () for timing inside a for loop but why would you as that effectively blocks program execution just as much as using delay (). The problem with your code is your using delay(). The cunningly named loop () function will allow you to repeat code as many times as you like, as frequently as you like if you use millis () for timing as in the BlinkWithoutDelay example. PCintPort::attachInterrupt(PIN3, &pin3func, CHANGE) īecause, of unavailability of hardware, I haven't tested this code. PinMode(PIN3, INPUT) digitalWrite(PIN3, HIGH) While ( digitalRead(alarmStop) & (count++
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