These easy-to-use ultrasonic rangefinders from Maxbotix work the same way as the EZ line that you know and love, but this new high-resolution series features 1 millimeter resolution! As with the rest of the Maxbotix range finders, these sensors feature Analog Voltage, RS232 Serial, and Pulse Width outputs making them easy to interface with any microcontroller. These sensors have a maximum range of 5000 mm (195 inches) with virtually no dead zone (although objects closer than 30 cm will typically range as 30 cm).
We're offering the EZ0, EZ1, 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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Based on 3 ratings:
Son used this range finder to build his Sr. project for high school. Very interesting project to help new trombone players learn slide positions. It was accurate and did the job very well.
pulse width is 10us/cm
PX4FLOW camera's for optical flow sensors can have this ultrasonic sensor attached to them for close in accurate detection of distance to objects (used in drones for flight sensor). However if you buy a PX4FLOW camera with this ultrasonic range finder integrated into it the cost jumps from around $60 to over $100.
I only saved a bit over $10 but learned a lot about these pixhawk compatible sensors and gained accuracy for auto-landing.