https://mzyy94.com/blog/2017/11/10/nanopineo2-homekit/

hb.sh

#!/bin/sh

TRANSMITTER="/usr/local/bin/transmitter"
SHAREDIR="/usr/local/share"
RUNDIR="/var/run"
GPIO="4"
COUNT=5

if [ ! $# -eq 2 ]; then
  echo "Usage: $0 accessory <on|off|state>"
  exit 1
fi

case "$2" in
  "on" | "off" )
    for i in $(seq 1 $COUNT); do
      sudo $TRANSMITTER $GPIO ${SHAREDIR}/${1}-${2}
    done
    echo ${2} | sudo tee ${RUNDIR}/${1}-state ;;
  "state" ) grep -s -q "on" ${RUNDIR}/${1}-state ;;
  * ) exit 2;;
esac

transmitter.c

#include <stdio.h>
#include <stdlib.h>
#include <wiringPi.h>

// gcc -o transmitter transmitter.c -lwiringPi -lpthread

#define BUF_LEN 1024

// 38kHz Frequency, 26.3usec, 1/3 duty
#define T 26
#define PULSE_HIGH 8
#define PULSE_LOW 18

void pulse(int pin, unsigned int msec) {
  const unsigned int count = msec / T;
  for (unsigned int i = 0; i < count; i++) {
    digitalWrite(pin, 1);
    delayMicroseconds(PULSE_HIGH);
    digitalWrite(pin, 0);
    delayMicroseconds(PULSE_LOW);
  }
}

void space(int pin, unsigned int msec) {
  digitalWrite(pin, 0);
  delayMicroseconds(msec);
}

unsigned int *load(FILE *fp, unsigned int *len) {
  char buf[BUF_LEN];
  char sign;
  unsigned int line = 0;

  while (fgets(buf, BUF_LEN, fp) != NULL)
    line++;

  if (line == 0) {
    fprintf(stderr, "File empty.");
    return NULL;
  }

  unsigned int *data = (unsigned int *)calloc(line + 1, sizeof(unsigned int));
  unsigned int *d = data;

  rewind(fp);
  fscanf(fp, "%c%*4c %u\n", &sign, d);
  if (sign == 'p') // pulse
    *d++;

  for (int i = 1; i < line; i++) {
    fscanf(fp, "%*5c %u\n", &(*d++));
  }

  *len = line;
  return data;
}

void emit(unsigned int *data, unsigned int len, int pin) {
  for (int i = 0; i < len; i += 2) {
    pulse(pin, data[i]);
    space(pin, data[i + 1]);
  }
}

int send(FILE *fp, int pin) {
  unsigned int len;

  unsigned int *data = load(fp, &len);
  fclose(fp);
  if (data == NULL)
    return 1;

  emit(data, len, pin);
  free(data);

  return 0;
}

int main(int argc, char *argv[]) {
  if (argc != 3) {
    printf("Usage: %s gpio-pin timing-file\n", argv[0]);
    return 1;
  }

  if (wiringPiSetup() == -1) {
    fprintf(stderr, "WiringPi setup error");
    return 1;
  }
  pinMode(atoi(argv[1]), OUTPUT);

  FILE *fp = fopen(argv[2], "r");
  if (fp == NULL) {
    fprintf(stderr, "File open error: %s", argv[2]);
    return 1;
  }

  return send(fp, atoi(argv[1]));
}