continued on the node, added a temperature library,

sensors/temperature/temperature/temperature.py

@@ -1,3 +1,43 @@
-def main():
-    print('Hi from temperature.')
+import rclpy
+from rclpy.node import Node
 
+from std_msgs.msg import String
+
+import temperature.temperature_lib
+
+
+class TemperaturePublisher(Node):
+
+    def __init__(self):
+        super().__init__('temperature_publisher')
+        self.publisher_ = self.create_publisher(String, 'topic', 10)
+        timer_period = 0.5  # seconds
+        self.timer = self.create_timer(timer_period, self.timer_callback)
+        self.i = 0
+        self.Temperature = temperature.temperature_lib.TemperatureModule()
+
+    def timer_callback(self):
+        msg = String()
+        #msg.data = 'Hello World: %d' % self.i
+        msg.data = self.Temperature.get_temperature()
+        self.publisher_.publish(msg)
+        self.get_logger().info('Publishing: "%s"' % msg.data)
+        self.i += 1
+
+
+def main(args=None):
+    rclpy.init(args=args)
+
+    temperature_publisher = TemperaturePublisher()
+
+    rclpy.spin(temperature_publisher)
+
+    # Destroy the node explicitly
+    # (optional - otherwise it will be done automatically
+    # when the garbage collector destroys the node object)
+    temperature_publisher.destroy_node()
+    rclpy.shutdown()
+
+
+if __name__ == '__main__':
+    main()

sensors/temperature/temperature/temperature_lib.py

@@ -0,0 +1,39 @@
+import smbus
+import time
+#from MCP342x import MCP342x
+
+class TemperatureModule:
+
+    def __init__(self):
+
+        # Parameters
+        # to read temperature from arduino through I2C
+        self.i2c_adress = 0x08  
+
+        # init of I2C bus communication
+        self.bus = smbus.SMBus(1) #was 1 before
+
+        #time.sleep(1)
+
+
+    def get_temperature(self):
+        # Sometimes an I/O timeout or error happens, it will run again when the error disappears
+        try:  
+            #system_temperature = self.bus.read_byte_data(self.i2c_adress, 1)
+            #print(str(self.bus.read_byte_data(self.i2c_adress, 1)))
+            #system_temperature = "here is the temperature"
+            #system_temperature = str(self.bus.read_byte_data(self.i2c_adress, 1))
+
+            data_received = self.bus.read_i2c_block_data(self.i2c_adress, 0, 18)  # Read 16 bytes from address 0
+            string_received = ''.join(chr(i) for i in data_received).strip('\x00')  
+
+
+
+            return string_received
+
+        except IOError:
+            return
+
+
+    def shutdown(self):
+        self.bus.close()