Amazon, Intel, IBM and many other companies have started building Internet of Things platforms and cloud services. These services are exactly what I’ve been looking for as a way to safely and securely gain Internet access to my home automation system. I buy a lot of great products from Adafruit and discovered they have an IOT platform.  Adafruit.IO is a beta version and I started experimenting with their MQTT SDK this week.

My plan was to build a standalone test bed to learn how to publish sensor data to Adafruit.IO and subscribe to switches and triggers. I built the breadboard below with an ESP-1 to handle the MQTT interface and an ATMega328 to process environment sensors and the alarms (flashing LED and loud piezo buzzer).

Power was one challenge. I needed 3.3 volts for the ESP-1 and the ATMega328 (LM1117).  A 5 volt rail (7805)was needed for the MQ2 and PIR sensors. A 12 volt rail (power supply rated at 1 amp) was needed for the flashing LED and a loud piezo (not shown).

Programming two processors is an added complication but I’ve got the process down and its pretty reliable. The Arduino IDE is not state of the art but its much better than some of the development environments I used to work with in the olden days.

The photo below is my first prototype of a dashboard from Adafruit.IO

I’ve created feeds for humidity, temperature and light. The alarm button turns the flashing LED alarm light on and off pretty quickly. I’ll add gas and motion later tonight. I also want to test the trigger capability as well.

Sensors

• MQ2 gas sensor
• DHT11 temperature and humidity
• Photo resistor light
• PIR motion sensor

That’s it for now and it took me only a couple of days to get it working. The Adafruit.IO forum was also helpful and support was responding almost as fast as I posted questions.

I wanted to add video surveillance to my home automation project, which was a good excuse to add another Raspberry Pi to the project. I’d tried using an ATMega328 with the Pi but found it too cumbersome to write Python code and Arduino ATMega code. It worked with an I2C interface but I wanted something simpler.

The diagram below illustrates the Adafruit photo-board with all of the necessary interfaces to 5 volt and 3.3 volt devices.

Raspberry Pi Interface Board

Project Enclosure

Features of a Raspberry Pi 2 Surveillance project:

• Raspberry Pi 2 – REST server (HTTP communication and control)
• Surveillance – Raspberry Pi camera for video capture
• Panic Button – hardware debounced button (3.3 volts)
• Motion sensor – PIR sensor at 5 volts
• Night Light – large LED at 3.3 volts
• Identification – IR Sensor to check for “me”
• iBeacon sensor – BLE USB dongle checking for my iPhone iBeacon
• Alarm – 555 Timer driving a loud speaker

I enclosed the project in a plain wooden box. As you can see the cable management was a hassle with the hinge and external interfaces on the door.

Raspberry Pi Surveillance

All of the code is in Python. There are four main packages

1. REST server code
2. Hardware interace – interrupts
3. Camera controls with 2 rotating JPEG images
4. BLE iBeacon scanner

I will publish the code to GitHub when I get a chance.

Continuation of my ESP8266 DC power switch. Once I had the breadboard working I soldered the components onto an Adafruit Proto-Board and enclosed the electronics in an antique wooden box. I’ve been combining the “old” with the “new” by reusing old or antique wooden boxes as my Arduino, Raspberry Pi and ESP8266 projects.

Final Project Enclosure

The next version (there are always things to improve) will use a 220 Ohm resistor for the LED indicator. I will also add some type of relay for an AC version. I really like the cloths pin box which I found in an antique store in Kalispell, Montana.

ESP8266 Light Switch Design

The diagram depicts a modified version (new 220 Ohm resister, etc.) of the proto-board solution. I’ve also added pins to support debugging on the proto-board by providing RX, TX and GND pins from the ESP-1.

Another recent project is a cat entertainment center using a combination of servo controlled mice and feathers. For the prototype I used a wooden wine case (6 pack) and inserted 1-1/2 inch tubes and servos for two mice. A slot on the side uses another servo to pop out a feather. It has been very popular with Nebbie, our six month old kitty.

Features include the following:

• Dual ATMega328 chips (I2C master and slave)
• Adafruit 16-Channel 12-bit PWM/Servo Driver – I2C interface – PCA9685
• Bluefruit LE – Bluetooth Low Energy (BLE 4.0) – nRF8001 Breakout
• Two Piezo buzzers for mouselike sounds
• Two small vibration motors to simulate scatching
• Two IR LED emitters/receivers to detect cat proximity
• iPhone to control each servo / sounds
• Automated mode to pop mice out and in

One of the challenges was to make it robust enough to handle abuse from the kitty while at the same time “NOT HURTING” my kitty. Nebbie has pulled out the servos several times. She also runs over to the box as soon as she hears the servos power up.

This is a prototype of my battery powered PIR motion sensor unit that I have on my front porch. It has run for several months on 3 AA batteries. Larry gave me the idea to use the PIR output to drive a MOSFET power switch.

ATMega328 battery powered motion sensor

The ATMega328 and NRF24 radio are powered up by motion detected by the PIR sensor. In the setup() routine it determines which of the four outdoor sensor locations it has been installed in (front porch, back yard, etc.) by the 2 position DIP switch, configures the NRF24 radio (DIP determines mesh network parent and pipe addresses), sends a message to a mesh NRF24 router unit and then enters a null loop until it looses power (PIR goes low). I’ve used an Adafruit proto-board to build a more permanent version:

ATMega328 Motion Sensor Project

I’ve run this device for more than 3 months and it works great. My next prototype will use the same idea but replace the ATMega328 and NRF24 with an ESP-1 Wi-Fi client.

Another recent project with the ESP8266 was my Wi-Fi controlled light switch. I had a couple of LED desk laps that I wanted to control remotely from my Home Automation iPhone app.

Goals for the project:

• Use an ESP-1 to handle all of the processing (no ATMega328)
• Implement a simple REST web server to handle HTTP PUT commands
• Only use one 2.1mm power plug (Wi-Fi control has to use the lamp’s power cord)
• Be as efficient as possible and rely on a LM1117 voltage regulator for 3.3 volts
• Use a MOSFET to control power to the connected appliance (LED desk lamp)

This is a video of the first breadboard version of the light switch.

The next step is to create a more permanent protoboard (Adafruit product) and enclose it in an antique wooden project box.