You normally use a software timer to poll, or even place the function in loop(). Imagine you have a system with a mission-critical function, measuring water level and control the sump pump or doing something much more important. The elapsed time then is very unaccurate Why using ISR-based Hardware Timer Interrupt is better In loop(), using delay() function as an example. You'll see blynkTimer Software is blocked while system is connecting to WiFi / Internet / Blynk, as well as by blocking task This non-being-blocked important feature is absolutely necessary for mission-critical tasks. You can also have many (up to 16) timers to use. The ISR_Timer_Complex example will demonstrate the nearly perfect accuracy compared to software timers by printing the actual elapsed millisecs of each type of timers.īeing ISR-based timers, their executions are not blocked by bad-behaving functions / tasks, such as connecting to WiFi, Internet and Blynk services. This important feature is absolutely necessary for mission-critical tasks. Therefore, their executions are not blocked by bad-behaving functions / tasks. The most important feature is they're ISR-based timers. Now with these new 16 ISR-based timers, the maximum interval is practically unlimited (limited only by unsigned long milliseconds) while the accuracy is nearly perfect compared to software timers. Timers' interval is very long ( ulong millisecs). This library enables you to use Interrupt from Hardware Timers on an SAMD-based board, such as SAMD21 Nano-33-IoT, Adafruit SAMD51 Itsy-Bitsy M4, SparkFun SAMD51 MicroMod, etc.Īs Hardware Timers are rare, and very precious assets of any board, this library now enables you to use up to 16 ISR-based Timers, while consuming only 1 Hardware Timer. Please have a look at HOWTO Fix Multiple Definitions Linker Error Why do we need this SAMD_TimerInterrupt library Features SAMD21_MultiTimers on SAMD21 SAMD_NANO_33_IOT RepeatedAttachInterrupt_uS on SAMD21 SEEED_XIAO_M0 Change_Interval on Arduino SAMD21 SAMD_NANO_33_IOT ISR_16_Timers_Array on Arduino SAMD21 SAMD_NANO_33_IOT Argument_None on Arduino SAMD21 SAMD_NANO_33_IOT TimerInterruptTest on Adafruit SAMD51 ITSYBITSY_M4 ISR_Timer_Complex_WiFiNINA on Arduino SAMD21 SAMD_NANO_33_IOT using WiFiNINA 2.2 Set Hardware Timer Interval and attach Timer Interrupt Handler functions.2.1 Init Hardware Timer and ISR-based Timer.Using 16 ISR_based Timers from 1 Hardware Timer 1.2 Set Hardware Timer Interval and attach Timer Interrupt Handler function.HOWTO Fix Multiple Definitions Linker Error.Why using ISR-based Hardware Timer Interrupt is better.Why do we need this SAMD_TimerInterrupt library.As its name suggests, phase and frequency correct PWM allows control over the PWM frequency and it's possible to drive the servos at 50Hz with a 14-bit resolution. On the Uno timer1 outputs are on digital pins 9 and 10, enough to drive two servos. This means that you can't simultaneousely use libraries that require this timer. Phase and frequency correct PWM uses the 16-bit Timer1. As this hardware PWM isn't interrupt driven it should be unaffected by jitter caused by the GPS. I tried a lot of different ideas, the timer2 was my biggest hope and often mentioned in other forum topics.Ī possible solution is to use the Atmega 328P's phase and frequency correct PWM instead of the servo library. Now it gets loose: It looks like the Adafruit GPS Lib is useing timer1 for UNO boards, therefor I tried to use timer2 Lib for my servo. The arduino UNO has three timers I could use. That interrupt stop's also my PWM signals for the servo, therefore the servo starts to jitter, because it receives random signals. servo Library example: "sweep" OR servoTimer2 Library example: "servoTimer2"īoth GPS Libs are using an interrupt to read GPS signals.Adafruit GPS Library example: "parsing" OR TinyGPSplus-0.94b Library example: "DeviceExample".The Servo jitters as soon I pickup GPS data. Unfortunately never a solution which worked with my setup. I know this Problem, using a servo and a GPS sensor, is I guess well known.
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