Sensors in the projects
Programming hobbyists are facing different kinds of sensors which are necessary for their projects. Sometimes sensors are used for curiosity just for gathering and checking some physical parameters, but other makers use sensors and their parameters for practical reasons – to solve problems in their projects.
Sensors in Totem system
Variety of possible hardware and is astonishing. Major amount of products in the market are user friendly, so almost anyone can set up different kinds of sensors on Raspberry Pi or Arduino platforms.
Distance or echo sensor isn’t something new that can amaze, but anyway it is very handful for various projects, especially in robotics.
Totem has developed its own distance sensor, but let me explain whole idea behind.
Totem is introducing not only different hardware and software solutions for handy makers. Our team works on whole system which has more than just software and hardware. Our main goal is to lift up makers into new dimension where they will be able to materialize their projects in proficient and joyful way.
To do this we have introduced variety of mechanical parts, which lets you to accomplish major mechanical problems in DIY, hobbyists, robotics projects. And it is just a start! We also partly introduced our electronics and software and our totem bus . All this makes a complete building system where you are free to build your own very customizable projects without big quest of searching for mechanical, electronic parts in various shops. Our team goal is to provide freedom for builders.
Now lets go back to distance sensor. I’ll show how it works in Totem BUS perspective. Firstly we need hardware and brain (Raspberry Pi) which can run Totem BUS with intelligent broker.
We already introduced Totem bus conception on bluetooth and smartphones. In this case Totem bus runs on bluetooth baseboards and broker runs on smartphone. This approach is very user friendly, so definitely it can be managed easily. Totem bus is very flexible and lets me show another approach with Raspberry Pi.
We are running Totem Bus and broker on Raspberry Pi. Each function board has it’s own message list. We have already introduced Totem Bus and it is just a firsts steps of Totem Bus into wide world . Echo sensor board is one of many function boards. Base board gets sensible data from echo sensor board, reads-writes pins and etc. And then baseboard throws data into Totem bus and then broker manages it. From this video you can see data flow into broker. Thrown result – is distance from obstacle, measured in centimeters. this is useful data for various projects. But that’s just a beginning. Broker can manage up to 250+ devices in the system! So just imagine how complex systems you can build with Totem mechanics, electronics and Totem BUS.
How Totem distance sensor works
Actually simple physics are hidden behind this device. Principle is simple and works the same way as bats find their way in the nature – by ultrasound waves.
Board generating pulse width modulation signal into transceiver and it transmits ultrasound just before generating ultrasound one of timers begins to count. Transceiver pins are read on receiver in a short time. As ultrasound signal echoes back into receiver ear, electrical signal from transceiver pin rapidly soars. So when program finds peak, timer halts and than program getting time difference T diff. It’s time between transmission beginning and peak. T diff parameter can be used in calculations to get distance from nearest obstacle. Distance parameter relies on T diff, sound speed and temperature, but don’t forget that sound speed has dependency on temperature.
This is how it looks on oscilloscope:
Yellow graph illustrates generated PWM and blue graph shows electrical signal of receiver when ultrasound hits it. That’s how echo sensor works.
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