rISR version 1.1.0

rISR (Runtime Interrupt Service Routine) is a C library that allows you to bind interrupt vectors at runtime on the atmega328p chip. It is designed to be easy to use and provides a simple API for binding and un-binding ISRs (Interrupt Service Routines) to interrupt vectors.

Features

• Bind & unbind interrupt vectors at runtime
• Ability to add custom data pointers to each interrupt vector
• Fully supports Atmega328p's interrupts
• Arduino support

How to use

Prerequisites

Before you can use the rISR library, you will need to have the following installed on your machine:

• git
• avr toolchain

Or if you prefer Arduino framework:

• Arduino ide / Arduino cli

Installation

• Clone the rISR repo

git clone https://github.com/Mikxus/rISR.git

Or If you're using Arduino, you can also install the library by following these steps:

1. Go to the releases tab on the rISR repository
2. Download the latest version of the library as a .zip file
3. Open the Arduino IDE
4. Go to Sketch > Include Library > Add .ZIP Library
5. Select the downloaded .zip file and click open
6. The library should now be installed and ready to use in the Arduino IDE.

Example project

Next create new main.c or a sketch and copy over the example.

#include <stdbool.h>
#include <rISR.h>

__attribute__ ((signal)) void __vector_pin_blink()
{
    PORTB ^= 0b00010000;
    return;
}

int main() {

    /* Configure timer1 to interrupt as fast as possible */
    cli();
    TCCR1A = 0;
    TCCR1B = 0;
    TCNT1  = 0;
    PRR &= ~(1 << PRTIM1);
    OCR1A = 1;
    TCCR1B |= (1 << WGM12);
    TCCR1B |= (1 << CS10);
    TIMSK1 |= (1 << OCIE1B);

    /* Set pin PB4 to output */
    /* Pin 12 on arduino uno r3 */ 
    DDRB = 0b00010000;                    

    /* Bind isr to selected interrupt vector */
    bind_isr(TIMER1_COMPB_, __vector_pin_blink);
    sei();

    while (true){}
}

Note if you're using arduino. Change the int main() to void loop()

Then new create config.h file or edit rISR's config file. The config file should have the interrupt name uncommented to enable runtime binding for it.

#define TIMER1_COMPB_used

Compilation

• The library consists of header file, c file and a assembly file. These files need to have the interrupt definition config file included. To do this you'll need to add -include path/to/config.h to avr-gcc's input.

Example makefile

Create new Makefile and copy the following content to it, while replacing "path_to_" with the path to the rISR src folder.

CC := avr-gcc
CFLAGS := -Wall --param=min-pagesize=0
BOARD := atmega328p
BUILD_DIR := build

.PHONY: clean

main.c: $(BUILD_DIR)
    $(CC) -mmcu=$(BOARD) $(CFLAGS) $@ -include config.h path_to_rISR.c path_to_rISR.S -o $(BUILD_DIR)/main.o

$(BUILD_DIR):
    mkdir $(BUILD_DIR)

clean:
    rm -rf $(BUILD_DIR)

To build the example you can just run make

API reference

Bind an ISR to an interrupt vector.

void bind_isr(enum isr_vectors vector, vector_t isr);

Un-bind an ISR from an interrupt vector.

void unbind_isr(enum isr_vectors vector);

APIs for passing data pointers

Note the vector names for data pointers end in a _ptr suffix.

Example:

TIMER1_COMPB_ptr

Bind data pointer to interrupt vector.

void bind_isr_data_ptr(enum isr_vectors vector, void* pointer);

Unbind data pointer from a interrupt vector

void unbind_isr_data_ptr(enum isr_data_pointers vector, void* pointer);

Get binded data pointer

void *get_isr_data_ptr(enum isr_data_pointers vector);

License

This library is licensed under the MIT License. See LICENSE file for more information.