This is the fantastically easy to use sensor from Maxbotix. We are extremely pleased with the size, quality, and ease of use of this little range finder. The serial interface is a bit odd (it's RS232 instead of standard TTL), but the PWM and Analog interfaces will allow any micro to listen easily enough. The sensor provides very accurate readings of 0 to 255 inches (0 to 6.45m) in 1 inch increments with little or no dead zone!
Maxbotix is offering the EZ0, EZ1, EZ2, EZ3, and EZ4 with progressively narrower beam angles allowing the sensor to match the application. Please see beam width explanation below.
Control up to 10 sensors with only two pins! Checkout the Maxbotix FAQ listed below.
If the ultrasonic range finder indicates that it has an "RS232 Serial Output" and is outputting an inverting signal with the voltage level based on Vcc, you could just use an inverting circuit using a transistor to invert the signal. This is not a standard RS232 that uses +/-12V. There are a few methods of flipping this signal through hardware or software. The resources and going further will provide specific examples.
Inverting Signal w/ Hardware
Doing a quick test using a retired NPN transistor from our storefront, I was able to get it working based on the circuit using a RedBoard Programmed with Arduino. I was using an Arduino so Vcc in my circuit was 5V. Since it's basically two diodes within the transistor, you will want to use resistors to limit the current. I just used two 330Ohm resistors just like I was turning on an LED. You probably do not need to do this but the values might need to be adjusted when using it at higher speeds or if the transistor is not fully turning ON/OFF. Testing with a multimeter, it worked as expected. An input of 5V would result in 0V (logic LOW) on the output since the transistor was turning on. With an input of 0V, the transistor would not be conducting so the output would be held HIGH at 5V. Using an Arduino serial passthrough for further testing, I was able to view the ultrasonic sensor's output data without any problems.
"RS232" Output and Inverting w/ Software
Otherwise, you could be clever in writing your code to store the value and possibly apply some sort of logical NOT operation. In Arduino, there is a special feature using software serial that inverts the signal by setting a parameter to
true [ "Software Serial Constructor" – https://www.arduino.cc/en/Reference/SoftwareSerialConstructor ]. There was someone in the Arduino forums that provided example code to invert the output, parse the data, and output it through the serial monitor here => [ User "Goldthing" - http://forum.arduino.cc/index.php?topic=114808.msg864009#msg864009 ].
Connecting Ultrasonic Sensor to Raspberry Pi
There is a tutorial from MaxBotix that shows you how to connect ultrasonic sensors to Raspberry Pis => [ http://www.maxbotix.com/Raspberry-Pi-with-Ultrasonic-Sensors-144/ ]. Certain ultrasonic sensors listed in the article require an inverter. If the ultrasonic range finder's output serial output is " RS232 " like the sensors listed under "Ultrasonic Sensors that Require an Inverter" , this indicates that the signal is basically an inverted output with the voltage level based on Vcc.
Therefore, you would need to follow the tutorial and use a serial inverter in order to use it with the Raspberry Pi. If you are using a Raspberry Pi a transistor, Vcc should be 3.3V since the Pi uses a 3.3V system.
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Skill Level: Noob - Some basic soldering is required, but it is limited to a just a few pins, basic through-hole soldering, and couple (if any) polarized components. A basic soldering iron is all you should need.
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If a board needs code or communicates somehow, you're going to need to know how to program or interface with it. The programming skill is all about communication and code.
Skill Level: Rookie - You will need a better fundamental understand of what code is, and how it works. You will be using beginner-level software and development tools like Arduino. You will be dealing directly with code, but numerous examples and libraries are available. Sensors or shields will communicate with serial or TTL.
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If it requires power, you need to know how much, what all the pins do, and how to hook it up. You may need to reference datasheets, schematics, and know the ins and outs of electronics.
Skill Level: Competent - You will be required to reference a datasheet or schematic to know how to use a component. Your knowledge of a datasheet will only require basic features like power requirements, pinouts, or communications type. Also, you may need a power supply that?s greater than 12V or more than 1A worth of current.
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Based on 6 ratings:
Super easy to hook up and start using in my project
The range finding is very accurate. Its doing a wonderful job for its size and price
Worked as advertised. Really nice.
When using more than one on a project, some trial and error may be necessary to get them to work using the Maxbotix wiring schemes. Micro and millisecond timing using Arduinos and other controllers is not accurate so actual pulse timing may not correspond to your coding.
I tried a few sensors and this was the most consistent. Works great on walls and other flat surfaces. I'm using it to detect people, which is a more abstract object, so the range is less and sometimes gives bad readings. But for the most part, I'm happy with the purchase. Would buy again.
The sensor I bought can not measure the distance below 14cm or 5 inches. In other words, if the distance below it, the value always show "14cm or 5 inches", but the another sensor EZ4 works fine.
something wrong with my code?
value = pulseIn(sensorPin, HIGH) ; cm = value /58; inches = value / 147;