Implement printing temperature on display

iot/Makefile

@@ -1,3 +1,5 @@
-all: main.c brokers/mqtt.c brokers/amqp.c temperature.c device_id.c
+FILES=main.c brokers/mqtt.c brokers/amqp.c devices/temperature.c devices/display.c device_id.c
-	$(CC) -lmosquitto -lrabbitmq -lpthread -li2c main.c brokers/mqtt.c brokers/amqp.c temperature.c device_id.c
+
+all: $(FILES)
+	$(CC) -lmosquitto -lrabbitmq -lpthread -li2c $(FILES)
 

iot/devices/display.c

@@ -0,0 +1,60 @@
+#include <linux/i2c-dev.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <fcntl.h>
+#include <string.h>
+#include <errno.h>
+#include <sys/ioctl.h>
+#include <i2c/smbus.h>
+
+#include "display.h"
+
+#define JHD1313_BUS "/dev/i2c-2"
+#define JHD1313_ADR 0x3e
+
+void display_set_cursor_pos(display_handle_t display, int x, int y)
+{
+	i2c_smbus_write_byte_data(display, 0x00, (y ? 0xC0 : 0x80) + x);
+}
+
+void display_write_str(display_handle_t display, char *str)
+{
+	while (*str) {
+		display_write_char(display, *str);
+		str++;
+	}
+}
+
+void display_write_char(display_handle_t display, char ch)
+{
+	i2c_smbus_write_byte_data(display, 0x40, ch);
+}
+
+display_handle_t init_display()
+{
+	int file = open(JHD1313_BUS, O_RDWR);
+
+	if (file < 0) {
+		perror("Error opening display device");
+		exit(EXIT_FAILURE);
+	}
+
+	if (ioctl(file, I2C_SLAVE, JHD1313_ADR) == -1) {
+		fprintf(stderr, "ERROR: setting address %d on i2c bus %s with ioctl() - %s", JHD1313_ADR, JHD1313_BUS, strerror(errno));
+		exit(EXIT_FAILURE);
+	}
+
+	// 2 line mode, 5x8
+	i2c_smbus_write_byte_data(file, 0x00, 0x28);
+	// Display on, cursor on, blink off
+	i2c_smbus_write_byte_data(file, 0x00, 0x0C);
+	// Display clear
+	i2c_smbus_write_byte_data(file, 0x00, 0x01);
+	// Entry mode set
+	i2c_smbus_write_byte_data(file, 0x00, 0x06);
+
+	i2c_smbus_write_byte_data(file, 0x00, 0x02);
+
+	return file;
+}
+

iot/devices/display.h

@@ -0,0 +1,10 @@
+typedef int display_handle_t;
+
+display_handle_t init_display();
+
+void display_set_cursor_pos(display_handle_t display, int x, int y);
+
+void display_write_str(display_handle_t display, char *str);
+
+void display_write_char(display_handle_t display, char ch);
+

iot/devices/temperature.c

@@ -11,8 +11,10 @@
 
 #include "temperature.h"
 
-#define MPC9808_BUS	"/dev/i2c-2"
+#define MCP9808_BUS	"/dev/i2c-2"
-#define MPC9808_ADR	0x18
+#define MCP9808_ADR	0x18
+#define MCP9808_MANID 0x0054
+#define MCP9808_DEVID 0x04
 
 #define CONFIG_REG 0x01
 #define TUPPER_REG 0x02
@@ -53,16 +55,16 @@ double get_temperature(temperature_handle_t file)
 
 temperature_handle_t init_temperature(void)
 {
-	int file = open(MPC9808_BUS, O_RDWR);
+	int file = open(MCP9808_BUS, O_RDWR);
 
 	if (file < 0) {
-		fprintf(stderr, "Error opening temperature sensor device (%s): %s\n", MPC9808_BUS, strerror(errno));
+		perror("Error opening temperature sensor device");
-		exit(1);
+		exit(EXIT_FAILURE);
 	}
 
-	if (ioctl(file, I2C_SLAVE, MPC9808_ADR) == -1) {
+	if (ioctl(file, I2C_SLAVE, MCP9808_ADR) == -1) {
-		fprintf(stderr, "ERROR: setting  address %d on i2c bus %s with ioctl() - %s", MPC9808_ADR, MPC9808_BUS, strerror(errno));
+		fprintf(stderr, "ERROR: setting address %d on i2c bus %s with ioctl() - %s", MCP9808_ADR, MCP9808_BUS, strerror(errno));
-		exit(1);
+		exit(EXIT_FAILURE);
 	}
 
 	int32_t reg32;
@@ -73,23 +75,23 @@ temperature_handle_t init_temperature(void)
 	reg32 = i2c_smbus_read_word_data(file, MANID_REG);
 
 	if (reg32 < 0) {
-			fprintf(stderr, "ERROR: Read failed  on i2c bus register %d - %s\n",  MANID_REG,strerror(errno));
+		fprintf(stderr, "Read failed on i2c bus register %d: %s\n", MANID_REG, strerror(errno));
-			exit(1);
+		exit(EXIT_FAILURE);
 	}
-	if (bswap_16(reg16poi[0]) != 0x0054) {
+	if (bswap_16(reg16poi[0]) != MCP9808_MANID) {
-		fprintf(stderr, "Manufactorer ID wrong is 0x%x should be 0x54\n",__bswap_16(reg16poi[0]));
+		fprintf(stderr, "Invalid manufacturer ID: Expected 0x%x, got 0x%x\n", MCP9808_MANID, __bswap_16(reg16poi[0]));
-		exit(1);
+		exit(EXIT_FAILURE);
 	}
 
 	// Read device ID and revision
 	reg32 = i2c_smbus_read_word_data(file, DEVID_REG);
 	if (reg32 < 0) {
-		fprintf(stderr, "ERROR: Read failed  on i2c bus register %d - %s\n",  DEVID_REG,strerror(errno) );
+		fprintf(stderr, "Read failed on i2c bus register %d - %s\n", DEVID_REG, strerror(errno));
-		exit(1);
+		exit(EXIT_FAILURE);
 	}
-	if (reg8poi[0] != 0x04) {
+	if (reg8poi[0] != MCP9808_DEVID) {
-		fprintf(stderr, "Manufactorer ID OK but device ID wrong is 0x%x should be 0x4\n",reg8poi[0]);
+		fprintf(stderr, "Invalid device ID - expected 0x%x, got 0x%x\n", MCP9808_DEVID, reg8poi[0]);
-		exit(1);
+		exit(EXIT_FAILURE);
 	}
 
 	return file;

iot/main.c

@@ -7,7 +7,8 @@
 #include <time.h>
 
 #include "brokers/amqp.h"
-#include "temperature.h"
+#include "devices/temperature.h"
+#include "devices/display.h"
 #include "device_id.h"
 
 void *watch_temperature(void *arg)
@@ -16,14 +17,21 @@ void *watch_temperature(void *arg)
 
 	printf("Device ID: %s\n", device_id);
 
-	temperature_handle_t temp_handle = init_temperature();
+	display_handle_t display = init_display();
+	display_write_str(display, " ");
+	display_set_cursor_pos(display, 0, 1);
+	display_write_str(display, "Device.....");
+	display_write_str(display, device_id);
 
+	temperature_handle_t temp_handle = init_temperature();
 	get_temperature(temp_handle);
 
 	while (true) {
+		// Retrieve data
 		double temperature = get_temperature(temp_handle);
 		size_t timestamp = time(NULL);
 
+		// Send JSON
 		char *format = "{"
 			"\"temperature\": %lf,"
 			"\"device_id\": \"%s\","
@@ -37,6 +45,15 @@ void *watch_temperature(void *arg)
 
 		free(str);
 
+		// Print on display
+		str = malloc(17);
+		sprintf(str, "===[ %.1lf\xDF" "C ]===", temperature);
+
+		display_set_cursor_pos(display, 0, 0);
+		display_write_str(display, str);
+
+		free(str);
+
 		printf("Temperature: %lf\n", temperature);
 
 		sleep(60);