io: refactor

03_io_access/Makefile

@@ -0,0 +1,39 @@
+CC = gcc
+CFLAGS = -Wall -Ilib
+LDFLAGS = -lgpiod
+
+# Directories
+SRCDIR = src
+LIBDIR = lib
+OBJDIR = obj
+
+# Source files
+LIB_SOURCES = $(wildcard $(LIBDIR)/*.c)
+SRC_SOURCES = $(wildcard $(SRCDIR)/*.c)
+
+# Object files
+LIB_OBJECTS = $(LIB_SOURCES:$(LIBDIR)/%.c=$(OBJDIR)/%.o)
+SRC_OBJECTS = $(SRC_SOURCES:$(SRCDIR)/%.c=$(OBJDIR)/%.o)
+
+# Target executable
+TARGET = io
+
+# Create obj directory if it doesn't exist
+$(shell mkdir -p $(OBJDIR))
+
+# Rules
+all: $(TARGET)
+
+$(TARGET): $(LIB_OBJECTS) $(SRC_OBJECTS)
+	$(CC) $(LIB_OBJECTS) $(SRC_OBJECTS) -o $@ $(LDFLAGS)
+
+$(OBJDIR)/%.o: $(LIBDIR)/%.c
+	$(CC) $(CFLAGS) -c $< -o $@
+
+$(OBJDIR)/%.o: $(SRCDIR)/%.c
+	$(CC) $(CFLAGS) -c $< -o $@
+
+clean:
+	rm -f $(OBJDIR)/*.o $(TARGET)
+
+.PHONY: all clean

03_io_access/README.md

@@ -0,0 +1,11 @@
+# IO Access
+
+This program demonstrates how to access the GPIO pins on the Raspberry Pi using
+a LED, a button and a temperature sensor.
+
+## Usage
+
+```bash
+$ make
+$ ./io
+```

03_io_access/lib/io.c

@@ -0,0 +1,116 @@
+#include <fcntl.h> // For open()
+#include <gpiod.h> // For libgpiod functions
+#include <stdio.h> // For perror()
+#include <stdlib.h> // For atof() 
+#include <unistd.h> // For close()
+#include "io.h"
+
+// Global variables for GPIO chip and lines
+static struct gpiod_chip *chip = NULL;
+static struct gpiod_line *led_line = NULL;
+static struct gpiod_line *button_line = NULL;
+
+// Error handling function
+static int handle_error(const char *msg) {
+    perror(msg);
+    return -1;
+}
+
+// Helper function to initialize a GPIO line
+static struct gpiod_line* init_gpio_line(int pin, const char *consumer, int direction) {
+    struct gpiod_line *line = gpiod_chip_get_line(chip, pin);
+    if (!line) {
+        handle_error("Failed to get GPIO line");
+        return NULL;
+    }
+
+    int request_result;
+    if (direction == GPIOD_LINE_DIRECTION_OUTPUT) {
+        request_result = gpiod_line_request_output(line, consumer, 0);
+    } else {
+        request_result = gpiod_line_request_input(line, consumer);
+    }
+
+    if (request_result < 0) {
+        handle_error("Failed to request GPIO line");
+        return NULL;
+    }
+
+    return line;
+}
+
+// Initialize GPIO chip and lines
+// Call cleanup_gpio() to release resources
+int initialize_gpio(const char *chip_name, int led_pin, int button_pin) {
+    chip = gpiod_chip_open_by_name(chip_name);
+    if (!chip) return handle_error("Failed to open GPIO chip");
+
+    led_line = init_gpio_line(led_pin, "gpio-led", GPIOD_LINE_DIRECTION_OUTPUT);
+    if (!led_line) return -1;
+
+    button_line = init_gpio_line(button_pin, "gpio-button", GPIOD_LINE_DIRECTION_INPUT);
+    if (!button_line) return -1;
+
+    return 0;
+}
+
+// Set LED state
+void set_led_state(int state) {
+    if (led_line) {
+        gpiod_line_set_value(led_line, state);
+    }
+}
+
+// Read button state
+int read_button_state() {
+    if (button_line) {
+        return gpiod_line_get_value(button_line);
+    }
+    return -1; // Return an error if button_line is not initialized
+}
+
+// Cleanup GPIO resources
+void cleanup_gpio() {
+    if (led_line) {
+        gpiod_line_release(led_line);
+        led_line = NULL;
+    }
+    if (button_line) {
+        gpiod_line_release(button_line);
+        button_line = NULL;
+    }
+    if (chip) {
+        gpiod_chip_close(chip);
+        chip = NULL;
+    }
+}
+
+// Error handling function for temperature reading
+static float handle_temp_error(const char *msg) {
+    perror(msg);
+    return -1.0;
+}
+
+// Read temperature from sensor
+float read_temperature(const char *sensor_path) {
+    int fd;
+    float temperature;
+    char buf[16];  // Large enough to hold the temperature string
+
+    fd = open(sensor_path, O_RDONLY);
+    if (fd == -1) {
+        return handle_temp_error("Failed to open temperature file");
+    }
+
+    ssize_t numRead = read(fd, buf, sizeof(buf) - 1);
+    if (numRead == -1) {
+        close(fd);
+        return handle_temp_error("Failed to read temperature file");
+    }
+
+    buf[numRead] = '\0';  // Null-terminate the string
+    temperature = atof(buf) / 1000.0;  // Convert the string to a float
+    close(fd);
+
+    return temperature;
+}

03_io_access/lib/io.h

@@ -0,0 +1,19 @@
+#ifndef IO_LIB_H
+#define IO_LIB_H
+
+// Function to initialize the GPIO chip, LED line, and Button line
+int initialize_gpio(const char *chip_name, int led_pin, int button_pin);
+
+// Function to set the LED state
+void set_led_state(int state);
+
+// Function to read the Button state
+int read_button_state();
+
+// Function to cleanup the GPIO chip, LED line, and Button line
+void cleanup_gpio();
+
+// Function to read the temperature from a sensor
+float read_temperature(const char *sensor_path);
+
+#endif // LIB_H

03_io_access/src/main.c

@@ -0,0 +1,31 @@
+// This document implements some function to interact with an 
+// Raspberry Pi 4 and some external components.
+// Used components: DS18B20, and LED and a push button.
+
+// libgpiod is used for the communication with the GPIOs
+#include <unistd.h>  // For sleep()
+#include <stdio.h>   // For printf()
+#include "io.h"
+
+#define GPIO_CHIP    "gpiochip0"
+#define LED_GPIO_PIN     18
+#define BUTTON_GPIO_PIN  22
+#define LED_BLINK_TIME   1  // Blink delay in seconds
+#define SENSOR_PATH   "/sys/bus/w1/devices/28-000000306565/temperature"  // DS18B20 sensor address
+
+int main(void) {
+    if (initialize_gpio(GPIO_CHIP, LED_GPIO_PIN, BUTTON_GPIO_PIN) < 0) {
+        return 1;
+    }
+
+    for (int i = 0; i < 10; i++) { // Blink the LED 10 times for demonstration
+        set_led_state(1);  // Turn the LED on
+        sleep(LED_BLINK_TIME);
+        set_led_state(0);  // Turn the LED off
+        sleep(LED_BLINK_TIME);
+        printf("Button state: %d\n", read_button_state());
+        printf("Temperature: %.2f\n", read_temperature(SENSOR_PATH));
+    }
+    cleanup_gpio();
+    return 0;
+}

Makefile

@@ -1,15 +0,0 @@
-CC=gcc
-CFLAGS=-lgpiod
-TARGET=io
-
-all: $(TARGET) 
-
-$(TARGET): io.c
-	$(CC) -o $(TARGET) io.c $(CFLAGS)
-
-run:
-	./$(TARGET)
-
-clean:
-	rm -f $(TARGET)
-

README.md

@@ -3,5 +3,6 @@
 This repo contains my code for the Distributed Embedded Systems course at the University of Rostock.
 
 ```bash
-gcc -o io io.c -lgpiod && ./io
+make
+./io
 ```

io.c

@@ -1,129 +0,0 @@
-// This document implements some function to interact with an 
-// Raspberry Pi 4 and some external components.
-// Used components: DS18B20, and LED and a push button.
-
-// libgpiod is used for the communication with the GPIOs
-#include <gpiod.h>
-#include <stdio.h>
-#include <unistd.h>  // For sleep()
-#include <fcntl.h>
-
-
-#define GPIO_CHIP    "gpiochip0"
-#define LED_GPIO_PIN     18
-#define BUTTON_GPIO_PIN  22
-#define LED_BLINK_TIME   1  // Blink delay in seconds
-#define SENSOR_PATH   "/sys/bus/w1/devices/28-000000306565/temperature"  // DS18B20 sensor address
-
-// function to set the LED state by passing the pin and state
-void set_led(int pin, int state) {
-    struct gpiod_chip *chip;
-    struct gpiod_line *line;
-
-    chip = gpiod_chip_open_by_name(GPIO_CHIP);
-    if (!chip) {
-        perror("Failed to open GPIO chip");
-        return;
-    }
-
-    line = gpiod_chip_get_line(chip, pin);
-    if (!line) {
-        perror("Failed to get GPIO line");
-        gpiod_chip_close(chip);
-        return;
-    }
-
-    if (gpiod_line_request_output(line, "gpio-led", 0) < 0) {
-        perror("Failed to request line as output");
-        gpiod_chip_close(chip);
-        return;
-    }
-
-    // Set the LED state
-    gpiod_line_set_value(line, state);
-
-    // Release the GPIO line and chip
-    gpiod_line_release(line);
-    gpiod_chip_close(chip);
-}
-
-// function to blink the LED by passing the pin, number of blinks and the delay
-void blink_led(int pin, int time, int delay) {
-    for (int i = 0; i < time; i++) {
-        set_led(pin, 1);
-        sleep(delay);
-        set_led(pin, 0);
-        sleep(delay);
-    }
-}
-
-float read_temperature() {
-	int fd;
-	float temperature;
-    char buf[16];  // Large enough to hold the temperature string
-
-    fd = open(SENSOR_PATH, O_RDONLY);
-    if (fd == -1) {
-        perror("Failed to open temperature file");
-        return -1;  // Return an error indicator
-    }
-
-    ssize_t numRead = read(fd, buf, sizeof(buf) - 1);
-    if (numRead == -1) {
-        perror("Failed to read temperature file");
-        close(fd);
-        return -1;  // Return an error indicator
-    }
-
-    buf[numRead] = '\0';  // Null-terminate the string
-    temperature = atof(buf) / 1000;  // Convert the string to an integer
-    close(fd);
-
-    return temperature;
-}
-
-// funciton to read button status
-int read_button(int pin) {
-    struct gpiod_chip *chip;
-    struct gpiod_line *line;
-    int value;
-
-    chip = gpiod_chip_open_by_name(GPIO_CHIP);
-    if (!chip) {
-        perror("Failed to open GPIO chip");
-        return -1;
-    }
-
-    line = gpiod_chip_get_line(chip, pin);
-    if (!line) {
-        perror("Failed to get GPIO line");
-        gpiod_chip_close(chip);
-        return -1;
-    }
-
-    if (gpiod_line_request_input(line, "gpio-button") < 0) {
-        perror("Failed to request line as input");
-        gpiod_chip_close(chip);
-        return -1;
-    }
-
-    value = gpiod_line_get_value(line);
-
-    // Release the GPIO line and chip
-    gpiod_line_release(line);
-    gpiod_chip_close(chip);
-
-    return value;
-}
-
-int main(void) {
-//    printf("Temperature: %.2f\n", read_temperature(SENSOR_ADDRESS));
-//    blink_led(LED_GPIO_PIN, 5, LED_BLINK_TIME);
-//	printf("Temperature: %.2f\n", read_temperature());
-    //	check button status and sleep for a second
-    while(1){
-        printf("Button status: %d\n", read_button(BUTTON_GPIO_PIN));
-        sleep(1);
-    }
-    return 0;
-}