What’s more, DFRduino Mega2560 can work steadily even when only powered by a 3.7V lithium battery.ĭFRduino Mega2560 is an ATmega2560-based microcontroller that provides full compatibility with "Arduino MEGA2560“. In addition to optimizing the overheating issue, it offers a wider input voltage range. If the interruption is too long, maybe the motor reached the end of its track but you can’t stop its rotation yet till the interruption is not over, so that will result into something bad.The new version of DFRduino Mega2560 has improved the VIN power supply circuit by changing the easily overheat LDO to DC-DC circuit for ensuring safety and reliability in long-term use. So what if you are controlling the position of a step motor. On the same reason, if an interruption is too long, remember that during interruption, the rest of the code is on pause. In this way, the interruption is as fast as possible. So what I recommend you is to just change values of variables in the ISR routine and then, let all the rest of calculations, decisions and so on, to be made in the void loop. In conclusion, we must make the ISR routine as fast as possible. That means if one pins triggers an interruption and in just a few moments a different pin triggers another interruption while we are still running the first interruption routine, the second interruption won’t trigger. When we are inside an interruption, the rest of interruptions are on pause. Part 6.2 - Have in mind (2 PCINT from same port)Īnother thing to have in mind. Once these lines are executed, the interruption flag goes back to "1" and these lines of code won’t run again till another interruption of pin D5 is triggered. Between the brackets we add our interruption code. This it the interruption loop for port D. So in the code, after or before the void loop, we add the lines below. So we have to add the code for the PCINT2_vect ISR. To sum it all uo, in the example before, we have set digital pin D5 to trigger interruption. We now have all the elements that we need to explain how pin change interrupts work. ISR (PCINT2_vect) for pin group D0 to D7.ISR (PCINT1_vect) for pin group A0 to A5.ISR (PCINT0_vect) for pin group D8 to D13.We have 3 vectors, PCINT0 vect for pins from D8 to D13, PCINT1 vect for pins from A0 to A5 and PCINT2 vect for pins from D0 to D7. For that, in the code we define the ISR and then we add the vector. This is a loop in the code that when the interruption flag is triggered it will execute. Well, each of the 3 groups of pins has a ISR or Interrupt Service Routine. But as you remember, when the interruption is triggered, we pause the main code and we jump to the interruption vector where we execute the code for that interruption. Ok so at this moment we know how to set pins to be able to trigger interruptions. We set bit 5 of the PCMSK2 register to a 1, so PCINT21 is enabled and that represents digital pin D5 as you can see in the tables above. But then with the second line of code we make digital pin D5 to be able to trigger interrupt. Ok, as you can see below, first, as in the example before we activate PCINT for group PCIE2 with the first line of code. below you have the registers and bits of each in order to select any of the PCINT bits. Setting it to a 0, it means the pin won’t trigger interruption on pin change. Now setting a PCINT bit to a 1, it means that pin will trigger interruption. For that we have the registers PCMSK0, PCMSK1 and PCMSK2 (Pin Change Mask), in which each bit indicates whether or not the pin triggers the PCINT. Once the PCINT is activated for a group of pins, we must say which pins of that group can trigger the interrupt. So how could we change a variable used in function 3 for example, while we are still running function 1. Even more, if we press the push button while function 1 is still running, with the lines of code below, we won’t detect that the button was pressed, because the digital read won’t run till function 1 and 2 are done. Since the Arduino code is sequential, is obvious that function 2 won’t run till function 1 is not over, and function 3 won’t run till function 1 and 2 are over. Between the functions we read the state of two pins connected to some push buttons. The second function calculates some PID values and the third function apply the PID result to some analog outputs to control a heater. The first reads the temperature from a thermocouple. For example, in the code below we run 3 functions (1, 2 and 3) and we read some inputs from some buttons. You should already know that the Arduino code is sequential, running in series meaning that till one instruction is not over, we can’t execute the next interruption.
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