Implement buzzer alarm

iot/Makefile

@@ -1,5 +1,7 @@
-FILES=main.c brokers/mqtt.c brokers/amqp.c devices/temperature.c devices/display.c device_id.c
+FILES=main.c brokers/mqtt.c brokers/amqp.c devices/temperature.c devices/display.c devices/buzzer.c device_id.c
+
+# libgpiod version must be < 2.0
 
 all: $(FILES)
-	$(CC) -lmosquitto -lrabbitmq -lpthread -li2c $(FILES)
+	$(CC) -lmosquitto -lrabbitmq -lpthread -li2c -lgpiod $(FILES)
 

iot/devices/buzzer.c

@@ -0,0 +1,44 @@
+#include <gpiod.h>
+#include <stdio.h>
+#include <unistd.h>
+
+#include "buzzer.h"
+
+buzzer_handle_t init_buzzer()
+{
+	struct gpiod_chip *chip = gpiod_chip_open_by_name("gpiochip1");
+	if (chip == NULL) {
+		fprintf(stderr, "Unable to find gpiochip1\n");
+		exit(EXIT_FAILURE);
+	}
+
+	struct gpiod_line *line = gpiod_chip_get_line(chip, 19);
+	if (line == NULL) {
+		fprintf(stderr, "Unable to get line 19\n");
+		exit(EXIT_FAILURE);
+	}
+
+	gpiod_line_request_output(line, "buzzer", 0);
+
+	return (buzzer_handle_t) {
+		chip,
+		line,
+	};
+}
+
+void sound_buzzer(buzzer_handle_t buzzer, int delay, int length)
+{
+	for (int cycle = 0; cycle < length; cycle++) {
+		gpiod_line_set_value(buzzer.line, 1);
+		usleep(delay);
+		gpiod_line_set_value(buzzer.line, 0);
+		usleep(delay);
+	}
+}
+
+void destroy_buzzer(buzzer_handle_t buzzer)
+{
+	gpiod_line_release(buzzer.line);
+	gpiod_chip_close(buzzer.chip);
+}
+

iot/devices/buzzer.h

@@ -0,0 +1,13 @@
+#include <gpiod.h>
+
+typedef struct {
+	struct gpiod_chip *chip;
+	struct gpiod_line *line;
+} buzzer_handle_t;
+
+buzzer_handle_t init_buzzer();
+
+void sound_buzzer(buzzer_handle_t buzzer, int delay, int length);
+
+void destroy_buzzer(buzzer_handle_t buzzer);
+

iot/main.c

@@ -9,10 +9,29 @@
 #include "brokers/amqp.h"
 #include "devices/temperature.h"
 #include "devices/display.h"
+#include "devices/buzzer.h"
 #include "device_id.h"
 
+void *sound_alarm(void *arg)
+{
+	buzzer_handle_t buzzer = init_buzzer();
+
+	int delay = 170, length = 600;
+
+	for (int i = 0; i < 5; i++) {
+		sound_buzzer(buzzer, delay, length);
+
+		usleep(delay * 2 * length);
+	}
+
+	return NULL;
+}
+
 void *watch_temperature(void *arg)
 {
+	// TODO change
+	int max_temperature = 27, min_temperature = 18;
+
 	char *device_id = get_device_id();
 
 	printf("Device ID: %s\n", device_id);
@@ -54,6 +73,12 @@ void *watch_temperature(void *arg)
 
 		free(str);
 
+		// Sound alarm if applicable
+		if (temperature < min_temperature || temperature > max_temperature) {
+			pthread_t alarm_thread;
+			pthread_create(&alarm_thread, NULL, sound_alarm, NULL);
+		}
+
 		printf("Temperature: %lf\n", temperature);
 
 		sleep(60);