ECHO-PRO, 5 in 1 Ultrasonic Module (PWM, ANALOG, ASCII, DET & TEMP)

RhydoLabz “ECHO –PRO, 5in 1″ Ultrasonic Distance Sensor is an amazing product that provides very short to long-range detection and ranging with a resolution of 1mm. The ECHO-PRO is a 5 in 1 sensor module which output the distance data as Serial ASCII, Pulse width and Analog output. The module has an on board temperature sensor which outputs the ambient temperature via Serial ASCII. Apart from this the module is also equipped with Proximity sensing output, which will generate a high going signal if any object comes under the preset distance range (1.5-500cm). The ECHO-PRO can operate in “AUTO” mode as well as “Manual” mode. In “Auto” mode the module automatically send the ultrasonic signal and do the measurement and give the distance output, whereas “Manual” mode requires external triggering to initiate distance measurement.

Since there are various interfacing options (ASCII, PWM and ANALOG) available on the module as a standard, it will be easy for a developer to select the optimum one based on the resources available on the microcontroller. No need to buy and stock different modules. In auto mode, the module need mot be triggered saving a control pin. The user can easily interface it with a microcontroller is a free Input, analog or UART Rx pin is available. This module enables a programmer to read temperature value even if an analog pin is not available in that corresponding controller, making it highly versatile.

The sensor provides precise, stable non-contact distance measurements from about 1.8cm to 5 meters with very high accuracy which is way ahead of normal ultrasonic sensors. Its compact size, long range and ease of usability make it a handy sensor for distance measurement and mapping. The board can easily be interfaced to microcontroller RX pin (USART). This sensor is perfect for a number of applications that require you to perform distance measurements while moving or stationary. Naturally, robotics applications are very popular but you’ll also find this product to be useful in security systems or as an infrared replacement if so desired.

Features

  • Output : Serial ASCII, Pulse width, Analog, Temperature Output, Proximity Detector
  • Range : 1.5 cm to 500cm
  • Modes : Auto & Manual Mode Selection
  • Resolution : 1-mm (PWM, ASCII)
  • Accurate and Stable range data
  • Proximity range can be adjusted by Trim pot.
  • 10Hz reading rate
  • Internal temperature compensation
  • 40 kHz Ultrasonic sensor measures distance to objects
  • Virtually no sensor dead zone, objects closer than 1.8 cm will typically range as 1.8 cm
  • Real-time automatic calibration (voltage, Temperature, ambient noise)
  • Automatically Triggered at every 100 ms (Auto Mode)
  • On board Proximity Detection LED indication
  • On Board Burst LED Indicator shows measurement in progress
  • Operating voltage : 3.0V – 5.5V
  • Current : <20mA
  • Designed for easy integration into your project or product
  • Operational Temperature : 0°C to +65°C (+32°F to +149°F)
  • Mounting holes provided on the circuit board
  • 6-pin header makes it easy to connect using a servo extension cable, no soldering required
  • Professional EMI/RFI Complaint PCB Layout Design for Noise Reduction

Applications & Uses

  • Bin level measurement
  • Proximity zone detection
  • People detection
  • Robots ranging sensor
  • Autonomous navigation Distance measuring
  • Long range object detection

Pin Description

ECHO-PRO have 5 pins with bread board compatible DET (Proximity Detection), Gnd (Ground), +5 (Power Supply), PWM (Pulse Width Modulation output), ANG (Analog) and ASCII (Serial data) from right to left.

Layout

Modes of operation.

Echo-Pro is designed to operate in Two modes , Manual mode and Auto mode.

• Manual Mode :  Jumper  ( J1 ) Shorted
In manual mode, the module needs to be triggered by a External positive going pulse  by the user to do the Distance measurement . This trigger pulse should be provided at the PWM pin of the module with High-time ranging from 10µsec – 100µsec, typical value is 10µsec.  User need to provide the trigger pulse repeatedly every time  before reading DET, PWM, ANG or ASCII pins.
• Auto Mode :  Jumper ( J1 ) Open
Auto mode very easy  and In this mode, the module automatically triggers and do the distance measurement at every 100ms. In this mode  the user can blindly  read DET, PWM, ANG or ASCII pins.

 

 

Detailed Pin Description

1. DET Pin
DET Pin is an O/P Pin which will be used to show the status the of the Proximity sensing.  Proximity detection pin with a default state as LOW , produces a HIGH signal if an obstacle is present within the preset distance of that module. This preset distance could be varied from (1.5 – 500) cm depending upon its application by adjusting the trim pot (P1) on the back of the module . There is  an LED indicator that glows as the DET pin goes HIGH. In auto mode the Proximity detection operates without   any kind of support from an external micro controller or an external circuit . This  will help the developer to use most of the resources of their micro controller for other operations and if any objects comes near or distance to objects reduces ,they will get a interupt request, by connecting DET pin to “INTERRUPT” pin of the controller.  To avoid pulse chattering on preseted distance due to external noises ,we have provided a safety window of 1cm. For Example: Suppose the module Generate a HIGH pulse at a preset distance of 10 centimeter by an obtacle , the  DET Pin will go LOW only if the the distance to obstacle reaches 11 centimeter.
2. PWM Pin
PWM pin provides an output pulse with a HIGH time duration depends on the distance to the object.  hence the distance to the target can be measured from the width of this pulse. This pulse will be TTL signal with minimum width of 87uS to maximum width of 30mS. As per the sample circuit below, the PWM pin of the ECHO sensor is to be connected to RB2 of the HOST controller. The obtained value (pulse-width) in µSeconds represents  the  echo  time  and  further  calibrations  of  this  data  gives  you  the  obstacle  distance. Speed of ultrasonic wave is 347 m/s equivalent to 0 .0347cm/µsec (Temperature dependent)

As per the eqn: Speed = distance/time => echo distance (Ed) = echo speed(Ev) *echo time(Et) ie, distance (Ed) = 0.0347cm per µsec (Ev) * Et µsec
The obtained distance will be twice the actual distance since it gives the to and fro distance of the object as per the to and fro time equated to the equation: (ie, Et stands for 2Et).

Thus the obtained distance divided by 2 gives actual distance of the obstacle.
ie, Actual distance = Ed/2.As per the above illustration your equation is,

Ed = Ev * (Et/2) implies Et = 2 * Ed /Ev equivalent to Et = (2/0.0347) *Ed
Implies Et = 58 * Ed equivalent to Ed (in cm) = Et(in µsec)/58

For instance, assume the output waveform produced to be:
The width of the wave increases with increase in distance between ultrasonic sensor and obstacle.Above graph shows the width of wave i.e 11.617ms.Using this graph we can calculate the distance of object  from the sensor.Using above equation the resulting distance of the wave is 200cm.
ie, Ed (in cm) = Et(in µsec)/58
Echo time(Et)=11617 us
Ed=116170/58
Ed=200.29cm
Above graph shows wave with width of 1.336ms(distance between sensor and obstacle) and the calculated distance is 23 cm.
ie, Ed (in cm) = Et(in µsec)/58 ,
Echo time(Et)=1336 us
Ed =1336/58
Ed=23cm
Above graph shows wave with  width of .271 ms(distance between sensor and obstacle) and the calculated distance is 4.67cm.
ie, Ed (in cm) = Et(in µsec)/58 ,
Echo time(Et)=271 us
Ed=271/58
Ed= 4.67cm

Connection Details for Taking PWM Output

 

Sample Code For Reading PWM pin in Auto Mode

Sample Code For Reading PWM pin in Manual Mode

3. ANG Pin
Analog produces an analog output corresponding to the distance to the obstacle, i.e. 9.676mV corresponds to 1cm. This could be measured using an ADC (Analog to Digital Conversion) module. In the sample code provided below, ANG pin is assumed to be connected to ADC channel 6 of a PIC16F877A microcontroller. Default +Vref & –Vref of a PIC microcontroller ADC module is 5V & 0V respectively producing a 10bit digital value for 5v input equallent to 1023(decimal).
1023(decimal) = 5V

1023(decimal) = 5000mV
1(decimal)       = (5000/1023) mV
1(decimal)       = 4.887 mV

9.676mV corresponds to 1cm & D being the 10 bit ADC output,
Distance in cm =     [D*4.88]/9.676cm

For example; if the module produces an output of 2V
The ADC module in the microcontroller converts this 2V analog input to a digital value equivalent to 409.
Now to find the distance in centimeters corresponding to this ADC output.
From the above formulated equation,
Distance in cm =     [D*4.88]/9.676cm
Distance in cm =     [409*4.88]/9.676cm        // Substituting D with 409
Distance in cm =     206cm

Note: In manual mode, the analog voltage will be produced only when a trigger pulse is provided at the PWM pin of the module.

Connection Details for Taking Analog Output
Sample Code for Reading ANG pin in Auto Mode

Sample Code for Reading ANG pin in Manual Mode

4. ASCII Pin
ASCII Serial Data output produces a TTL (Transistor Transistor Logic) output at a baud rate of 9600 including both distance and temperature sensor outputs in the format “DXXX.XTXXX” along with a ‘\r’ symbolizing the end of the string. For example “D145.6T030” where ‘D’ followed by distance in centimeters and ‘T’ followed temperature in degree Celsius. Here the user doesn’t need to calibrate the value read making it easier to interface. Now what if an error occurs while calculating distance? At this point, the module displays an error message instead of displays false readings which greatly increases the reliability of the module. Error output will be in the format “ERRX.XTXXX” also followed by a ‘\r’ to denote the end of the string. For example “ERR0.1T039”, here by checking for an “ERR” in the received string, the user can distinguish valid data from error value.

Note: Serial data outputs calibrated distance & temperature readings, this temperature reading could only be obtained from ASCII pin.

Connection Details for Taking ASCII Output
Sample Code for Reading ASCII pin in Auto Mode

Sample Code for Reading ASCII pin in Manual Mode

How to Buy

Click here to buy rhydoLABZ ECHO-PRO ( 5 in 1 Distance Sensor Module)

Support

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Frequently Asked Questions(FAQ)

Q: Is it possible to take readings from DET, ASCII, ANG & PWM pins of the module?
Ans: Yes, you can. It provides output in all the four pins of the module once triggered. The point to be noted is the mode in which the module works. In auto mode, the module automatically triggers to produce an output in a constant rate. But in manual mode, the module outputs data only when a trigger pulse is produced externally.

Q: What will be the DET & ANG outputs in manual mode in the absence of trigger pulse?
Ans: In the absence of trigger the pulse, there won’t be any output in ASCII and PWM pins. But DET & ANG pins retains the previously produced output and changes only when it is triggered.

Q: I have designed a circuit for parallax ping ultrasonic sensor, will this module be compatible with the mentioned circuit?
Ans: Yes, it is compatible. GND, 5V & PWM pins of ECHO-PRO ultrasonic sensor is designed to match the pin-out of parallax ping ultrasonic sensor. Both sensor spacing and board dimensions matches the layout of parallax ping ultrasonic sensor.

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