Ultrasonic Rangefinder

The ultrasonic rangefinder features a one shot mode where distances up to 5.50m can be detected. Moreover, in this range, the reading is always within one centimeter of the true distance. The rangefinder can also detect velocities of objects within one meter per second for objects within 1.50m. Finally the rangefinder can enter scanning mode, where the transmitting and receiving transducers can be turned 45 degrees in either direction. Thus, the system can sweep across 90 degrees and find the distances. Because of its high accuracy and long range, the rangefinder can be used to find the distances for common household objects, and measure relatively short distances between objects. In addition, the rangefinder sweep mode can be used to get a profile of any surface. Finally a laser pointer is included to give the user an impression of what object in the distance is being measured.

 

Electrical characteristics

Parameter

Conditions

Min

Typ

Max

Units

Input Voltage (supply1, supply2)

T = 25oC

4, -

5, 12

6, 15

V

Current drawn

 

 

220

 

mA

Response time

T = 25oC

.26

 

108

ms

Detected distance

T = 25oC

.09

 

5.50

m

Detected distance

T = 5oC

.09

 

5.50

m

Max distance

Dry erase wall

 

 

5.50

m

 

Wood panel

 

 

4.80

m

 

Stucco

 

 

3.50

m

 

Painted wall

 

 

3.85

m

 

Metal cabinet

 

 

4.73

m

Distance Accuracy

T = 25oC

 

±1.0

 

cm

Velocities

T = 25oC

-3.0

 

3.0

m/s

Velocity accuracy

T = 25oC

 

±1.0

 

m/s

Velocity distance

T = 25oC

0.20

 

1.5

m

Temperature of operation1

 

5

 

40

oC

Degrees of detection

 

-45o

 

45o

 

Scan cycle speed

 

 

4*Response time

 

ms

Beam width

T = 25oC

 

 

90

degrees

1 note that at the temperature extremes, the device doesn’t function very well. To have full functionality, the device should be operated above 10oC.

Documentation:

  1. Full Documentation
  2. Block diagram
  3. Fully documented code
  4. The definition file
  5. Schematic
  6. PCB layout

More data sheets:

  1. Atmel AT8535 8-bit Microcontroller
  2. Atmel microcontroller instruction set
  3. LM311 (comparator)
  4. LM565 (IC phase lock loop)
  5. MAX4622 (2x 2:1 analog switch)