Skip to main content
Share Your Experience: Take the 2024 Developer Survey

Questions tagged [isr]

Interrupt Service Routine. A function which gets called in response to an interrupt signal.

Filter by
Sorted by
Tagged with
0 votes
1 answer
101 views

ESP-IDF logging library slows down ISR processing

I'm hacking a project with ESP32-WROOM module. I'm running some timers with alarms along with some peripherals triggering ISRs. In the ISR routine I'm sending events to a queue, and receiving them in ...
1 vote
0 answers
142 views

ESP32 trouble with running ledcWrite inside of ISR

ESP32-S2 (Wemos/Lolin S2 mini) Arduino 2.1.1 on Windows 11 Hello, Thank you for taking the time to read this post and for any assistance you can provide. I consider myself a newbie when it comes to ...
2 votes
2 answers
559 views

Using interrupts as flags/latches without any ISR

I've got an Arduino Mega periodically running an (~400ms) operation that is sensitive to repeatable timing, so I don't ever want it to be interrupted. But, I'd like to be able to use an interrupt ...
4 votes
2 answers
606 views

How to get around passing a variable into an ISR

Okay so you aren't able to pass a variable into in ISR. This is causing problems for me. I'm using a rotary encoder, and I need it to be connected to an interrupt pin and running a ISR. When using ...
2 votes
1 answer
120 views

Is ESP8266 dropping an interrupt?

I want to use interrupts on my ESP 8266 to monitor the digital outputs of a power meter and water meter. The idea is to increment a counter in the ISRs and at some point to take the value of the ...
4 votes
1 answer
156 views

Interrupts Within Critical Statements

I've redone a previous Arduino sketch I posted in which I was having trouble capturing encoder counts within critical statements, having no luck properly attaching and detaching interrupts. I've ...
0 votes
2 answers
422 views

Flow meter using Wemos Mini - ISR not in IRAM!

I'm trying to use a flow meter with Wemos Mini. Most tutorials are using Arduino boards ( which code and HW work OK ), but since I want this device to send alerts over the internet when abnormal usage/...
1 vote
0 answers
195 views

Using library functions in timer ISR ESP32

I'm trying to use a library function in my ISR function that uses the internal timer to trigger every 1 ms. The chip that I'm using is an ESP32-C3-MINI. Here is my current code: main.cpp #include <...
1 vote
1 answer
684 views

Correct usage of SPI with ISR

My Arduino needs to do: Run ISR as many times as possible/ as fast as possible. Occasionally receive data over I2C. Output data over SPI in ISR. My question is regarding SPI and ISR. The ...
1 vote
1 answer
81 views

How do I properly use an ISR inside a class definition?

I want to write a class for a model bike. For controlling the steering I use a DC motor with two encoders. To get the steering angle stAng of the bike, I attach a interrupt to the pin ST_ENC_A where ...
2 votes
1 answer
2k views

AttachInterrupt - fail to initiate inside a class [duplicate]

I'm trying to create a class that uses attachInterrupt, but get this error msg: In member function 'void ledDoor::attach()': ClosetLedStrip:31:82: error: invalid use of non-static member function ...
9 votes
2 answers
7k views

Arduino interruption (on pin change)

I use the interrupt function to fill an array with values received from digitalRead(). void setup() { Serial.begin(115200); attachInterrupt(0, test_func, CHANGE); } void test_func() { if (...
-1 votes
2 answers
301 views

Can't make attachInterrupt() work

I have an accel+gyro sensor connected to an Arduino Zero. It's configured to output an interrupt signal on pin 2 when tapped. I can do a digitalRead() on the pin, and it does go high, so the interrupt ...
2 votes
1 answer
209 views

Mildly accurate oscilloscope using Arduino Uno R3

I'm trying to make a mildly accurate oscilloscope using Arduino Uno R3 and I've done some research on the best method to do so. First of all I need to measure the voltage with a rather high sampling ...
4 votes
1 answer
635 views

ISR for very fast processes, strange code found. Has ISR effect on timer behaviour?

I found the following code within an example for performing very fast changes on a PWM-output. It works, however I'm wondering about some details. TIMER2 was set up in setup() as follows: TCCR2A = 0; ...
2 votes
1 answer
347 views

ATtiny85 giving multiple wake from IDLE if INT0 held low

Desired behaviour: Go to IDLE sleep mode. When PB2 (blue trace) goes low wake up and give a 10 ms HIGH on PB1 pulling a pull-up low (yellow trace on Figure 1). Go to 1. What I get: Figure 1. (1) ...
8 votes
2 answers
20k views

Why the need to use the volatile keyword on global variables when handling interrupts in Arduino?

I am familiar with the keyword Volatile being used to declare variables that are shared among multiple threads on a software application (basically on a multithreaded application). But why do I need ...
0 votes
1 answer
237 views

Arduino ISR timing question

Im trying to understand how the Arduino ISR keeps track of timing between pulses stored in a variable, if that variable is latter used. Say, for example, you have a magnet mounted on a circular ...
2 votes
1 answer
160 views

Hardware interrupt calling two ISRs

I've spent three days on this, and either I'm blind to something, or something just ain't right. Doorbell. Front door switch and back door switch. Two interrupt service routines, one attached to each ...
1 vote
1 answer
64 views

How to properly send bytes between RPI and Arduino over I2C while using ISR without IOerrors?

I have a I2C connection between an RPI 3B+ and Arduino Nano. I want to send a key and a corresponding value byte, and the arduino does something with that inside a timed ISR. Which works. But I get ...
3 votes
1 answer
91 views

Why no brackets after Interrupt routine inside attachInterrupt

I'm just curious as to why there are no brackets at the end of the ISR when attaching and assigning the interrupt command? attachInterrupt(digitalPinToInterrupt(interruptPin), blink, CHANGE); ... ...
1 vote
4 answers
192 views

Is there anything wrong with this code

Hi I'm pretty new to cpp. Could someone review my code and explain any pitfalls or problems? Below is the code and an example to read from a flow meter with a hall sensor. Thanks in advance. Greg /...
1 vote
1 answer
205 views

How do I temporarily disable TIMER5 Interrupts?

I have a fairly complex autonomous robot program that is getting into trouble when executing controlled turns. I constructed a very small program to test just the turns, and this works fine. When I ...
1 vote
0 answers
47 views

How do I synch the Arduino PID library with an external timer for turn-rate control?

I have been trying to use the Arduino PID library for controlling the rate of turn (in deg/sec) of a wall-following robot. The robot's operating system uses TIMER5 on an Arduino MEGA2560 to update a ...
1 vote
2 answers
2k views

How to exit out of a timer interrupt (ISR(TIMER1_COMPA_vect))

I have a code here where I collect an array of data and do some data analysis with the data. The only thing I'm struggle with is how to exit the ISR after I am done running my code. I am using a pre-...
1 vote
2 answers
199 views

Timer Interrupt Collision

I am working with a MEGA2560 trying to implement velocity ramps for three steppers at the same time. The goal is to move to different positions applying accelerations and decelerations while finishing ...
5 votes
4 answers
7k views

Is `millis()` affected by long ISRs?

I have a project that uses timers and interrupts frequently. A lot of CPU time is spent handling ISRs over an extended period of time. Would this affect code inside the main loop that relies on the ...
2 votes
2 answers
146 views

Why impedance between I/O pin and ground drops when Arduino is not powered

I have a 4KHz 5V pulsed signal connected to Arduino UNO pin2 (ISR). When the board is powered, the pulse is attached to ISR rising edge, and is working as intended. I don't know the output impedance ...
0 votes
1 answer
437 views

Arduino using delay in I2C receiveEvent

I have read before that you can't use delay() inside I2C receiveEvent because it is an ISR. What I want to do is as follows: I have a servo connected to my Arduino Uno and I want to control that using ...
0 votes
2 answers
10k views

Serial Interrupt

I want to create a simple program, that responds to me sending a character over the Arduino IDE console. I am using an arduino UNO. Here is my program: volatile bool MeasReceived=false; ISR(...
0 votes
1 answer
197 views

How to bridge free-running multichannel adc to serial?

I want to get meteo sensors values, and turn avr based 16mhz arduino (i have mega, but that seems not matter alot vs uno) into multichannel oscilloscope. Task details. Desired data rate is 8(uno) to ...
1 vote
0 answers
60 views

One ISR should be called, but both ISR has been called on Arduino UNO

I experimenting with the interrupt ISR using Arduino Uno. In my circuit, I am taking two mechanical switches that are connected with Uno's interrupt pins, pins 2 and 3, and also taking a built-in LED ...
0 votes
1 answer
932 views

Is there a better way to combine if statement with an ISR?

In my sketch when an interrupt gets triggered, a state variable is toggled from high to low and vice versa. Depending upon the variable state I have an if statement in the main loop that will call ...
0 votes
3 answers
3k views

Hardware Interrupt Triggered Randomly

So there is this pretty generic part of my project that involves triggering an ISR that will flip a boolean value. I have set up the software side like so: void setup() { attachInterrupt(...
1 vote
1 answer
967 views

Volatile variable not updating from timer ISR

I know this is a problem that has come up many times but I can't seem to get this code fragment to update the count variable on an ATMEGA328P. I am using an Arduino Uno as a development board, with ...
2 votes
1 answer
1k views

Arduino IDE with ATtiny85 error "multiple definition of `__vector_5"

I am having a problem compiling the code for my ATtiny85 circuit. I am using the timer/counter0 in normal mode so that when it overflows it triggers the TIMER0_OVF_vect ISR. When I have that ISR in ...
-1 votes
2 answers
71 views

buiReliable time in ISR

I'm using a Nano. The code below is a simplified workup of my problem code. The point of it is asynchronous debounced button press detection. The actual code sets a volatile bool to tell the main ...
0 votes
1 answer
2k views

real-time reading of a quadrature encoder at full resolution with only one interrupt on ATmega328

I want to read a quadrature rotary encoders at full resolution with only one interrupt on Arduino Nano (ATmega328). So I found out that we can use XOR to reach a full resolution: Where pin 3 ...
0 votes
2 answers
38 views

Is volatile qualifier needed if shared variable cannot be changed externally during complete function call?

Consider the following example: int i { 0 }; void incInt() { ++i; } int readInt() { return i; } setup() { Serial.begin(9600); attachInterrupt(digitalPinToInterrupt(D1), incInt, ...
0 votes
2 answers
5k views

how to interrupt the loop function and restart it?

I have a project with some NeoPixels and other LEDs and an Arduino UNO. Once switched on, the defaultLEDAnimation with colors and blinking, etc. starts. I want to trigger some other animations, so I ...
1 vote
1 answer
2k views

What is the call to cli(); routine in interrupt service routine for SPI?

I see this in examples of ISR code but what is it?
2 votes
0 answers
1k views

Does Proteus simulate external interrupts properly using Arduino? I can't get them to work

I am trying to simulate an interrupt with an Arduino Uno in Proteus. This is the simple test code that I'm using: void introutine() { digitalWrite(13,HIGH); } void setup() { pinMode(13,OUTPUT); ...
3 votes
3 answers
3k views

What is the right way to query an I2C device from an interrupt service routine?

The ADXL345, for example, requires that interrupts are responded to by querying the INT_SOURCE (interrupt source) register. In example code for the SparkFun ADXL345 Arduino Library, there is code that ...
1 vote
1 answer
168 views

Arduino Timer0 Piggyback

As described here https://learn.adafruit.com/multi-tasking-the-arduino-part-2/timers I use timer 0 to get my own timer with a milliseconds resolution. It is setup like this: void setup (void) { ...
0 votes
1 answer
58 views

ISR definition causing boot loop?

I am trying to compile and upload code to an Arduino Uno from the command-line, however I seem to be experiencing an odd issue. When I compile this code: #include <avr/interrupt.h> #include &...
1 vote
0 answers
62 views

can an ISR change the value passed by pointer while the subroutine is executing?

So I am working on a project where the board plays a song on a buzzer using PWM and I want the song to stop when i press an external button typedef enum stateType_enum{ waitPress, debouncePress, ...
2 votes
3 answers
3k views

Arduino delay inside of an Interrupt

Using the delay function inside of an ISR is frowned upon when programming in an Arduino. The general response to solve this desire is to design the program to delay in a more cleanly way outside of ...
-1 votes
1 answer
150 views

Does this sound like a good approach to decoding a dumb keypad?

The background: I bought a "dumb" 8-pin 4x4 keypad for use in a project. (This one: https://www.sparkfun.com/products/14881 It has a wire connected to each row, and a wire connected to each column. ...
4 votes
2 answers
863 views

Interrupts: use of the "volatile" keyword with a structure pointer for button debounce

I've written a small sketch targeted at the Arduino Uno (ATmega328P) to debounce a mechanical pushbutton using the summing/integration technique: #include <IntegratingDebounce.h> #define ...
0 votes
1 answer
346 views

How to stop sending the last received char of UART echo function?

I developed a code for uart based ISR with linear buffers, the problem is that it keep sending the last received char in Arduino IDE. Here's the application code: #include "uart_new.h" void setup() ...