Ultrasonic means the frequency of the sonic (sound) pulse is above the human hearing range. The highest frequency that is detectable by the human ear is approximately 20 KHz. In this project, I have used DYP-ME007 Ultrasonic range finder(URF). I bought this Ultrasonic range finder from Ebay.com and this is NOT a good experiment module. However, you can use it to understand and test how an ultrasonic range finder works. The performance of this URF is not as good as ping))). The important facts regarding this sensor is given below:
Working Voltage : 5V(DC)
Working Current : max 15 ma
Working frequency : 40HZ
Output Signal : 0-5V (Output high when obstacle in range)
Sentry Angle : max 15 degree
Sentry Distance : 2cm – 500cm
High-accuracy : 0.3cm
Input trigger signal : 10us TTL impulse
Echo signal : output TTL PWL signal
Size : 45*20*15mm
Supply module with 5V, the output will be 5V while obstacle is within range otherwise it outputs 0V.
Note : the module should be inserted in the circuit before giving power which avoids chances of misoperation ；if it does not work, power again.
Module Working Principle:
(1) IO trigger Pin(2) should be given HIGH LEVEL pulses of at least 10us.
(2) The module then starts sending ultrasonic sound of 40khz frequency and receives the pulses if there is any obstacle nearby.
(3) If there is signals returning, then the ECHO pin output high level pulses and the following formula is to used to calculate the distance of obstacle.
Test distance = (high level time * sound velocity ) / 2
where sound velocity= 340m/sec
How to send pulses of at least 10us?
– Circuit given below is 555 IC based astable multivibrator, this gives high level pulses at a period of 30us. The output pin 3 of 555 has been connected to trigger pin and the echo pin of URF has been taken to DIG 9 of Atmega328 (Pin 15 on chip)
First of all, make an Arduino Programmer on breadboard using FT232RL breakout board. It is very easy and you can get the tutorial on this link: CLICK HERE.You can also make the project using Arduino board, but if you want to make it independent of Arduino board, I recommend you to make the project on breadboard. The main advantage making on breadboard is that you can later solder the project on PCB.
The basic direction for making Arduino programmer can be achieved from the following picture.
Then, fix an 16×2 LCD with the programmer. I guess that you can see the used pins from the picture given below. You can also get tutorial here: CLICK HERE
ATmega328 and 16×2 connection-
Pin no. on Chip Pin no. on LCD
4 (DIG 2) 14
5(DIG 3) 13
6(DIG 4) 12
11(DIG 5) 11
12(DIG 6) 6
13(DIG 7) 4
Now, make the 555 based multivibrator
– Keep IC on breadboard; short pin 1 to GND; short Pin 2 to 6; insert 1M resistor across Pin 6 and 7.
– Insert 1K resistor across Pin 7 and Vcc(Power).
– Short Pin 4 and 8 and connect Pin 8 to Vcc(Power).
– Insert 22p capacitor across pin 2 and 1; and 0.1uF capacitor across Pin 5 and GND.
Now the 555 astable configuration is ready.
Then Insert URF on the breadboard.
After insertion on breadboard, it must look like this:
Finally the whole assembly would look like this.
Related experiment: Ultrasonic range finder using HC-SR04