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--- en:iot-open:remotelab:itt:servo [2019/10/27 10:52] – pczekalski
+++ en:iot-open:remotelab:itt:servo [2020/07/20 12:00] (current) – external edit 127.0.0.1
@@ Line 1: / Line 1: @@
+===== ITT Servo module =====
+This laboratory is located in the office of ITT Group in Tallinn, Estonia.
+==== Introduction  ====
+This laboratory can be used to practice controlling the servo motor attached to the controller.
+{{:en:iot:examples:servopicture2.jpg?300|}}
+==== Prerequisites ====
+For this laboratory, the student should understand basic MQTT concepts like topics, broker, subscribing and publishing.
+==== Technical details ====
+This laboratory consists of a servo with the add-on module attached to the ITT IoT controller module.
+=== Sensors ===
+This laboratory does not have any sensors.
+=== Specifications ===
+<table Ref.Tab.1.1>
+<caption>Servo specifications</caption>
+^ Specification ^ Value ^
+| Speed at 6V | 0,07 sec/60°|
+| Stall torque at 6V | 0,042 N-m |
+| Speed at 4,8V | 0,09 sec/60°|
+| Stall torque at 4,8V | 0,028 N-m |
+</table>
+=== Electrical connection ===
+The signal lead of the servo is connected to D3 pin of the controller.
+=== Software, libraries and externals ===
+  * ITTIoT libary - used to program the controller module.
+  * Servo libary - used to control the servo.
+=== Communication ===
+The user can connect and program this controller using the Distancelab environment.
+=== Limits ===
+At the same time, only one user can program the controller. But all users connected to the Distancelab MQTT broker can subscribe and publish to topics specified.
+==== Hands-on labs ====
+=== Example code ===
+<code c>
+/*
+ * IoT Servo example
+ *
+ * This example subscribe to the "servo" topic. When a message received, then it
+ * change servo position
+ *
+ * Created 11 Sept 2017 by Heiko Pikner
+ */
+#include <Arduino.h>
+#include <Servo.h>
+#include <ittiot.h>
+//Pin definition for the Servo (D3)
+#define SERVO_PIN            D3
+Servo myservo;  // create servo object to control a servo
+// Change the servo position (value between 0 and 180)
+// mosquitto_pub -u test -P test -t "RL/esp-{ESP-ID}/servo" -m "51"
+// = this calls servo motor to change position
+void iot_received(String topic, String msg)
+{
+  Serial.print("MSG FROM USER callback, topic: ");
+  Serial.print(topic);
+  Serial.print(" payload: ");
+  Serial.println(msg);
+  Serial.print("Servo: ");
+  Serial.println(msg);
+  myservo.write(msg.toInt());
+}
+// Function started after the connection to the server is established
+void iot_connected()
+{
+  Serial.println("MQTT connected callback");
+  // Subscribe to the topic "servo"
+  iot.subscribe("servo");
+  iot.log("IoT Servo example!");
+}
+void setup()
+{
+  Serial.begin(115200);
+  Serial.println("Booting");
+  // Print json config to serial
+  iot.printConfig();
+  // Initialize IoT library
+  iot.setup();
+  myservo.attach(SERVO_PIN);
+}
+void loop()
+{
+  // IoT behind the plan work, it should be periodically called
+  iot.handle();
+  delay(200);
+}
+</code>
+==== Support ====
+info@ittgroup.ee