First release of porting 'Infrared Multiprotocol' library from

Dependents:   IRMP_Receiver

IRMP - Infrared Multiprotocol Decoder

This library is a mbed version of the famous IRMP code, developed by members of the german forum It can receive and analyze a large number of infrared remote codes. In the original version there is also code for an IR transmitter, this will be added to this lib soon.

Base for this initial release is version 2.9.7 from 2015/11. A detailed description for this lib can be found here :

The code was originally written for AVR mikrocontrollers and has been ported to different platforms already. It works also great with the mbed target as it can use the unique I/O and ticker code.

Actually, the code uses the static C functions and is not ported to C++ yet to maintain compatibility to the original library. This requres the DigitalIn Pinname setting in the irmpconfig.h.

The required hardware is e.g. just an TSOP31238 (for 38 kHz modulated IR) or similar.


How to use

  • import this library
  • edit irmpconfig.h and turn on the desired protocols
  • change F_INTERRUPTS if necessary, check the protocol table for the minimum necessary frequency
  • search for 'IRMP_PIN' in the irmpconfig and replace with your hardware input

The irmp_ISR() must be called cyclic with a fixed frequency, a simple task for the mbed ticker. In the main program the result is checked by calling irmp_get_data(). This function returns the decoded protocol, address, command and flags like key pressed or released.


Tested platforms

  • simple LPC1347 board, works fine
  • EA LPC4088 QuickStart Board works fine
  • LPCXpresso1549 bad, there is a (known?) issue with slow Ticker ISR processing, ISR consumes >30µs instead of 3 µs
  • STM32F103 board: bad, also known problems with Ticker implementation
  • Test results with other boards are welcome.

Sample code

prints the information about decoded signals to stdout. The ISR contains additional code for performance mesuring which can be omitted in controlling applications.

Import programIRMP_Receiver

Sample code for IRMP library

Sample for decoding and performance test

#include "mbed.h"
#include "irmp.h"

#define LED_ON  0
#define LED_OFF 1

// LED as test output
DigitalOut led(LED1, LED_OFF);
DigitalOut flash(LED2, LED_OFF);

// cyclic interrupt for IRMP ISR worker
Ticker t;

// only for performance test
Timer   timerPerfTest;
int     timeISRMax = 0;
float   timeISRAvg;
int     timeISRAvgSum = 0;
int     countISRCalls = 0;

// this ISR must be called cyclic
void irmpISR(void)
    int t1 = timerPerfTest.read_us();               // read performance timer

    irmp_ISR();                                     // call irmp ISR

    int timeISR = timerPerfTest.read_us() - t1;     // calc time spent in worker ISR
    if (timeISR > timeISRMax)                       // store maximum
        timeISRMax = timeISR;
    timeISRAvgSum += timeISR;                       // sum for avg

int main() {
    printf("IRMP on mbed\n");

    led = LED_OFF;

    // irmp_data holds result of received IR code
    IRMP_DATA irmp_data;

    irmp_init();                                                            // initialize irmp
    t.attach_us(&irmpISR, 1E6 / F_INTERRUPTS);                              // call ISR 15.000 / s

    // infinite loop, interrupts will blink PORTD pins and handle UART communications.
    while (1)
        flash = !flash;     // test output. flashes at 15/2 kHz, you will not see it blinking

        // check for received IR commands
        if (irmp_get_data (&irmp_data))
            // ir signal decoded, do something here...
            // irmp_data.protocol is the protocol, see irmp.h
            // irmp_data.address is the address/manufacturer code of ir sender
            // irmp_data.command is the command code
            // irm_data.flags is press/release information
            // irmp_protocol_names[irmp_data.protocol] is the protocol name (if enabled, see irmpconfig.h)
            // printf("proto %d addr %d cmd %d\n", irmp_data.protocol, irmp_data.address, irmp_data.command );

            // sample decoding, turn LED on / off
            if (irmp_data.protocol == IRMP_RC5_PROTOCOL && irmp_data.address == 5)      // old RC5 VCR Remote. TV uses address 0
                if (irmp_data.flags == 0)       // switch only on button press
                    switch (irmp_data.command)
                    case 0:     // Key '0'
                        led = LED_OFF;
                    case 1:     // Key '1'
                        led = LED_ON;
                    case 53:        // Key 'play'
                        printf("bring me a beer!\n");
                    case 54:        // Key 'stop'
                        timeISRAvg = (float)timeISRAvgSum / countISRCalls;
                        timeISRAvgSum = 0;
                        countISRCalls = 0;
                        printf("ISR max / avg runtime [microseconds] : %d / %5.2f\n", timeISRMax, timeISRAvg);
                        timeISRMax = 0;

            // log to stdout
            printf("proto %d addr %d cmd %d flags %x name %s\n", irmp_data.protocol, irmp_data.address, irmp_data.command, irmp_data.flags, irmp_protocol_names[irmp_data.protocol] );

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