The sonar system pulls approximately 100ma of current while powered on and short bursts of 2 amps when pinging. Take this into account when calculating battery usage.

Next you’ll need to make a cable to connect the driver board to the robot’s expansion port. The expansion port uses a common 40 pin flat cable connector. Solder the wires from the 40 pin connector directly to the special flat cable which is normally provided with the driver board. If you don’t have the special flat cable which attaches to the driver board, you’ll need to solder the wires directly to the driver board. Follow the pin out shown. Make sure that the flat cable is installed in the driver board’s connector correctly.

Cable Pinout

Expansion Driver Board Connector Connector --------------------------------- 2 (Gnd) 1 (Gnd) 3 (+5v) 9 (+5v) 9 (P4) 4 (Init) 10 (P5) 7 (Echo) 11 (P6) 8 (Binh)

Mounting

Mount the driver board and transducer to ARobot’s body using metal or plastic brackets and hardware as needed. Drilling of the body may be necessary – prevent metal filings from getting on electronic circuits. Make sure that no wire or exposed part of the driver board makes contact with any metal hardware or the robot’s body. The picture below shows the transducer mounted to the body using a small metal bracket and a dab of the robot builder's best friend - hot glue.

Warning

The driver board and transducer my have 100 volts or more present at various locations. Do not touch!

Software

You can cut and paste this code example into your editor then download it to the Basic Stamp II for execution.

Or Download sonar.bs2 here.

'sonar example program.
dist	var	word		'sonar distance var.
redled	con	10
speaker	con	9
				'sonar pins.
init	con	4		'change these for different pins.
binh	con	6
echo	con	5


output init			'sonar init.
output binh			'sonar binh.
output speaker			'speaker output.
output redled			'red led.
input echo			'echo pin.

				'setup for sonar.
low init				'init pin.
low binh				'binh pin.

low speaker			'turn off speaker.
low redled			'turn on red led.

test
	gosub sonar		'get sonar reading.
	debug dec ? dist		'print it to serial port.
	pause 1000		'pause 1 sec.
	goto test			'loop back.



sonar
	high init			'hit transducer.
	pause 1			'pause for ringing.
	high binh			'raise inhibit.

	rctime echo,0,dist		'wait for echo.

	dist=dist/73+9		'dist has number of inches.
				'offset for ringing is 9 inches.
				'sound travels 1 inch in about 73us.
				'rctime increments in 2us increments.

	pause 40			'give it a rest.
	low init			'reset sonar stuff.
	low binh
	return			'done.

Links

The Polaroid 6500 driver and transducer can be purchased from Wirz Electronics. See their web site at www.wirz.com.

Here's some other Polaroid Sonar Links of interest:

• http://www.cs.umd.edu/users/musliner/sonar/notes - Sonar Notes by David J. Musliner
• http://www.acroname.com/robotics/parts/R15-SONAR2.html - Acroname Polaroid Sonar Information
• http://www.abe.msstate.edu/fto/classes/ee4723/group2.html - The Physics of Ultrasonic Ranging by Gary Dion, Wyatt Francis, Thomas Dodd
• http://www.cs.umd.edu/users/musliner/sonar/muxsonar.asm - How to Mux Sonar