Since the ISR is called some time after that (and that is what toggles the pin) you will see the pin toggle every 1 ms. However if you wait too long then you miss the overflow update, and then the result returned will go down (i.e you will get 253, 254, 255, 0, 1, 2, 3 etc. 1 Answer Sorted by: 2 However on an oscilloscope I see the pin toggle each 1ms. It now supports 16 ISR-based timers, while consuming only 1 Hardware Timer. Each of the timers has a counter that is incremented on each tick of the timers clock. This library enables you to use Interrupt from Hardware Timers on an Arduino, Adafruit or Sparkfun AVR board, such as Nano, UNO, Mega, Leonardo, YUN, Teensy, Feather32u4, Feather328P, Pro Micro, etc. Thus, even inside an ISR, you can rely on micros() updating. 1.The Uno has three timers called timer0, timer1, and timer2. It then adds in the Timer 0 overflow count, which is updated by a timer overflow interrupt (multiplied by 256). I have found a lot of good examples, but Im not sure on how to changes the timing values to get the 9.6kHz (or 104 microseconds) trigger timing. I'm avoiding using a library because I'm wanting to keep the code light weight. Program a timer to generate an interrupt every 1 microsecond. dannyboyfl September 15, 2015, 3:14pm 1 I'm trying to create a timer that triggers a function at 104s. It always reads the current hardware timer (possibly TCNT0) which is constantly being updated by the hardware (in fact, every 4 µs because of the prescaler of 64). In Arduino, there is a handy function called micros() which return you the microseconds. I found the following code and adapted it to the ATMEGA 328. That way they won't conflict with each other because there will be some time between each of the three interrupts (overflow, compare A and compare B). Simply set the compare interrupts to occur at 1/3rd and 2/3rds of the overflow period. Timing issues are very critical so I had to find a way to use timer interrupts. It is possible to use the Timer0 compare interrupts without affecting the millis() and micros() functions. The other answers are very good, but I want to elaborate on how micros() works. Arduino, Electronic Arduino Timer Interrupt I am actually working on a small project using an Arduino micro-controller ATMEGA 328.
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