A list of hardware components for the sensor package and how to put them all together.
The hardware setup for this project requires some basic knowledge of circuits and soldering techniques. This guide was written by Morgan Bounds.
These are the materials that were used; the resistors, PCB and jumper wires can be substituted with any equivalent product. Different sensors or microcontrollers can also be substituted, but that will require you to modify the circuits and the software. Do so at your own discretion. The retailers we purchased from are marked with a . Additionally, you will need any tools and supplies you require for soldering.
The PCB in Figure 2 serves as the hub for the circuit shown in Figure 1. The Ground, Voltage Supply, and Trigger pins for the sensors are all common. They can be connected to a single pin from the microcontroller. The PCB we used only has two rails on it, as shown in Figure 2 these were used for the Voltage and Trigger pins. The common ground came from soldering jumpers in the green section to connect all of the Ground pins. The Echo pins each need their own pin on the microcontroller and could bypass the PCB if they were not 5V pins. The Raspberry Pi can only handle 3V on its GPIO pins so the voltage must be brought down to safe levels to keep from damaging the microcontroller. This is the reason for the resistors shown in the circuit. Solder your 1kOhm resistors where the blue lines are shown in Figure 2. For our testing purposes the PCB was put together with fairly long hookup wires so that the sensors could be moved around. When hooking up your own circuit be sure to minimize both the number of connections you have to make, and the length of your wires. Extra connections create more possible failure points, and excess wire adds weight and clutter.
To connect the Raspberry Pi to the PCB Circuit, follow the labels and pinout diagram shown in Figure 3 above. Connect pin 02 to the common Voltage Supply rail, pin 06 to the common Ground rail, and pin 23 to the common Trigger rail. The GPIO’s used as ECHO pins will connect to one side of the resistors soldered onto the PCB. The order does matter as ECHO’s 0 through 9 represent Sensors 1 through 10 in the software.
To connect the sensors, connect the 5V, GND, and TRIG pins from each sensor to the corresponding common rails. Then connect the ECHO pins to the other side of the 1kOhm resistors.
To reduce noise in the results we constructed shielding for the sensors. We created shielding for sensor pairs and individual sensors. To produce accurate and consistent copies we 3D printed our shielding. The SolidWorks files used to create the shielding are on the downloads page of this site. The angles used in the shield designs allowed for a 40 degree cone of detection. The plastic shielding worked well in testing, but it could warp beyond usability in the heat of a building fire. These SolidWorks files can be used to create molds for a more appropriate material.