Hi, this is Wayne again with a topic “Weekend Projects – Cellular Sensor Sentinel”.
Hi, I’m Craig Kooten editorial assistant with make in today’s weekend project we’ll be building a remote alarm system that uses your cell network to send text messages when it picks up an event. It can detect movement, contact, proximity and changes in ambient light, and it’s easy to modify with other kinds of sensors for your own custom applications. It was designed and built by Adam Wolfe of Wayne and Lane, and we call it the cellular sensor Sentinel. You will need these parts to complete the project head over to your local Radio.
Shack, where you can pick up most of the components needed for the build you’ll also need these basic tools will show you how to connect four simple sensors to detect different events. A simple homemade contact sensor will respond to pressure and an even simpler DIY. Capacitance sensor can sense. The proximity of many objects, including people, an off-the-shelf passive infrared motion, sensor, picks up movement and a basic light sensor will detect changes in ambient light levels. We’Ll start the project by building the contact sensor, cut a long, rectangle out of cardboard and then cut and glue two smaller rectangles of aluminum foil to the cardboard as shown next crease, the cardboard in the middle and fold, the foil covered surfaces toward each other cut.
Two sections of drinking straw and attach them across the foil on one side of the sensor by folding them around the back and securing the two ends. With tape now attach alligator clips to two opposing corners and cut out the adjacent corners so that the clips will not short across the gap when the sensor is folded over close the sensor and check its operation with the continuity tester on your multimeter, the straws hold The foil surfaces apart, but when something presses down on the middle they make contact and close the circuit. Now, let’s build the capacitive sensor. It works by detecting the change in capacitance or the ability to hold an electric charge of a metal film when it comes in proximity with another object to build the sensor cut a rectangle out of cardboard and cover one side with aluminum foil next attach an alligator Clip to the foil: that’s it seriously! That’S it! Now: let’s build a battery pack to make logic mobile, simply solder, a power connector to the battery pack wires and reattach its sleeve. Now all you have to do is fill it with double-a batteries and it’s ready to power. Your Arduino, if you haven’t already visit the project page for links to the Arduino software, appropriate libraries, an example code upload the code open the serial, monitor and set the baud rate to one one. Five, two: zero zero.
You should see hello world appear in the serial monitor window now, it’s time to add the GSM start by installing your SIM card connecting the antenna and setting two jumpers to software serial now plug the shield into your Arduino and power it up via the USB plug Open the serial monitor and set the baud rate to one one: five: two: zero: zero. You should see the green LED, light up on the board and the serial monitor should print ready. Now it’s time to wire up the sensors start by plugging in the PIR motion sensor to the end of the shield, with the output connected to pin to VCC connected to pin three and ground connected to pin four next add the light sensor by connecting the short Leg to ground and a long leg to a zero now connect one of the contacts switch alligator clips to the ground leg of the light sensor and the other alligator clip to a small piece of wire inserted into pin 10 connect. The capacitive sensor last add a 10 mega ohm resistor between pins 11 and 12 and attach the alligator clip from the sensor to the resistor lead at pin 12. That’S it all.
Four sensors are ready to go before we can deploy the project. We need to do some testing, because this project sends text messages and text messages can cost you money texting is disabled. By default, we can test the sensors with texting disabled because the Arduino will print to the serial monitor when it would have sent a text open. Your do we know serial monitor with the baud rate set to one one: five, two: zero zero.
You should be able to see a hello world message shortly, followed by the GSM shield, turning on put your hand in front of the PIR sensor and verify that the serial monitor reports, the correct event, next press and release the contact sensor, you should see a press Event and a release event on the serial monitor the capacitive sensor needs a little configuration first. It probably won’t work well on battery power, so if you’re using batteries set cap sensor enabled to false otherwise you need to set the lower and upper thresholds in the code. The raw sensor value will print to the screen a few times. A second watch, the numbers, as you put your hand, closer and further away from the sensor and set the high and low thresholds accordingly. The last step is to test the cellular functionality set SMS number to a valid outgoing phone number. You also need to replace the default phone number with the number of the phone you want to receive.
The text when the sensor signal is activated confirm that min m/s between SMS is relatively high, how high? Let’S start with at least thirty thousand milliseconds, which is thirty seconds. This will prevent a potentially expensive flurry of text messages if something goes wrong with the sensors. Finally, set SMS enabled and send SMS at startup to true to enable texting then re-upload the code to your Arduino.
Now you can test the whole system power. Everything up and open the serial monitor. The shield should send a text message, keep an eye on the serial monitor window for error reports after 30 seconds or so unplug the Arduino, and wait for the SMS to come through on the outgoing number it shouldn’t take too long, though delivery time will vary with Network congestion, the text message will contain the trigger reason, the state of all the sensors and the time it was sent.
Once the text message arrives successfully, you’ll be ready to deploy, you can use the battery pack, a wall wart or the USB cable to power. The sensor Sentinel place, the sensor Sentinel knew your garbage can to detect and text you when your pup is being a rascal put it inside of your birdhouse to sense and notify you. When that rare bird is back and ready for you to snap that award-winning photo the cellular sensor, Sentinel is designed to be versatile.
You can easily add more sensors to detect humidity barometric pressure, magnetic fields, acceleration, vibration flexing tilt or almost anything you can imagine, be sure to check out the project page for ideas on additional hacks and modifications. It’S also a great place to ask questions and share your own, build you .