https://github.com/AdamJHowell/CeilingFan
This project uses an Arduino compatible device to control an inexpensive radio-controlled helicopter.
My intent is to use this as a ceiling fan, with a 450-class electric helicopter fastened upside down to the ceiling. I can then control the helicopter using MQTT.
This could also work as a bench test device for any radio-controlled project.
When powered on, this device will connect to the Wi-Fi network defined in networkVariables.h, then connect to the MQTT broker configured in that same file, and finally subscribe to the "mqttServo" topic. When messages are published to that topic, this device will receive those messages, and act accordingly.
| Item | Cost | Quantity | Total |
|---|---|---|---|
| HiLetgo ESP8266 NodeMCU ESP-12E | 7.99 | 1 | 7.99 |
| ELEGOO 4 channel 5v relay module | 7.99 | 1 | 7.99 |
| Hobby King HK450 CCPM radio-controlled helicopter (T-rex clone) | 39.06 | 1 | 39.06 |
| Turnigy Typhoon 450H 2215H Heli Motor 3550kv | 13.75 | 1 | 13.75 |
| Hobbyking SS Series 25-30A ESC | 7.70 | 1 | 7.70 |
| Corona 919MG Digital Metal Gear Servo | 7.09 | 4 | 28.36 |
| Antec NEO480 PSU (or any spare PSU you have) | 80.00 | 1 | 80.00 |
| Electronics-Salon 24/20-pin ATX DC Power Supply Breakout Board Module | 12.99 | 1 | 12.99 |
| Hookup wire (various) | 2.00 | 1 | 2.00 |
| 13.30 | 0 | 0.00 | |
| Total | 199.84 |
ESP8266 boards commonly have two different widths between rows of pins: 0.9" (23mm) and 1.1" (28mm). When purchasing a NodeMCU board holder (or motor shield), ensure the width of the shield matches the width of your ESP.
Tailoring this code to your Electronic Speed Control (ESC) may require trial and error. I found this side helpful: http://techvalleyprojects.blogspot.com/2012/06/arduino-control-escmotor-tutorial.html
Perhaps the most important takeaway from that is to NEVER connect your Arduino power pins to an ESC! Modern ESCs have a Battery Elimination Circuitry (BEC) that can feedback to the ESP. The ESC should be powered by an XT60 connector, and the ESC servo pins should connect to ground and signal, but the middle power pin should NOT be connected to anything!
Other important takeaways are that the motor may not start turning until a value such as 50 is used (~2000 ms PWM), and the motor may stop turning at non-zero values (like 20).
- Cyclic/Collective Pitch Mixing (CCPM) Servo lead signal pins connected to GPIO4 (D2), GPIO14 (D5), and GPIO12 (D6). At least one servo will need to be reversed, which is done in software.
- ESC servo lead signal pin connected to GPIO5 (D1).
- Rudder servo lead signal pin connected to GPIO15 (D8).
- Connect black or brown servo wires to ground.
- Connect red servo wires to +5V, but do not connect the red ESC servo wire to anything!
- Connect white, orange, or yellow servo wires to signal.
- Ensure the ESC is provided enough amperage via the XT60 connector.
- Floodlight LEDs connected to a relay that is connected to GPIO14 (D5).
- TLOF (Touchdown LiftOFf area) circular LED string connected to a relay that is connected to GPIO12 (D7).
- FATO (Final Approach/Take Off) square LED string connected to a relay that is connected to GPIO13 (D7).
- ESP8266WiFi.h provides the network client for MQTT to use, and Wi-Fi functions used to connect to a local area network in station mode.
- PubSubClient.h by Nick O'Leary, provides the MQTT client. This program only uses MQTT to subscribe to a broker, it does not publish any messages at this time.
- Adafruit_PWMServoDriver provides the methods used to configure and control servos in software.
- ArduinoJson by Benoît Blanchon, wrangles our data into and out of JSON format.
- A MQTT broker that this device can subscribe to is required. I will not cover how to set up a MQTT broker. I have tested with Mosquitto and FairCom Edge. Both are simple to install and configure.
- A client will publish MQTT messages to the broker. Those messages will be sent this device, which will react to the message according to the API detailed below.
- The ESP8266 Wi-Fi module handles all IP layer communications.
The API for this project is a simple two-character string, where the first character is a key designating the device to be controlled or the action to be performed, and the second character (a decimal digit) is a value representing the setting for that device. For lighting, zero extinguishes the light, and any non-zero value will illuminate the light.
First character (key):
| Key | Component or action |
|---|---|
| t | throttle servo |
| c | collective servo |
| r | rudder servo |
| f | floodlight LEDs |
| l | green TLOF circle LEDs |
| a | white FATO square LEDs |
| k | kill switch (turn off throttle/ESC, turn off all lights, move all servos to neutral, second character is ignored) |
Second character (value):
| Value | LED effect | Servo effect | ESC effect |
|---|---|---|---|
| 0 | off | maximum CCW position | off |
| 1 | on | 20° from CCW position | 11% of maximum speed |
| 2 | on | 40° from CCW position | 22% of maximum speed |
| 3 | on | 60° from CCW position | 33% of maximum speed |
| 4 | on | 80° from CCW position | 44% of maximum speed |
| 5 | on | 100° from CCW position | 55% of maximum speed |
| 6 | on | 120° from CCW position | 66% of maximum speed |
| 7 | on | 140° from CCW position | 77% of maximum speed |
| 8 | on | 160° from CCW position | 88% of maximum speed |
| 9 | on | maximum CW position | maximum speed |
For servos, the 0-9 API value is multiplied by 20 to put it in a 0-180 range needed for the Arduino servo API.
The default topic of "mqttServo" is set with the 'mqttTopic' global constant in the networkVariables.h file. The default MQTT broker address and port are also set using global constants in that file.
A sample message using the Mosquitto command line utility, sending a key of c and a value of 8,
which will set the collective to 160° (70° downward pitch, pushing air away from the helicopter, towards the floor):
mosquitto_pub -h 127.0.0.1 -p 1883 -i testPublish -t mqttServo -m "c8"
No attempt is made to use QoS levels greater than 0. This sketch is only a subscriber, and makes no attempt to respond with QoS acknowledgements.