Harvey Mudd College
Computer Science 154
Sonar Setup Page

• Please read through these directions before setting up a sonar!



• There should be five sonars (and batteries, and circuits...) on the table beside the duckhunt-playing machine. As of 2/23/05, all five of these have been tested (on the laptop Ed/Joe/Max are using).



• Sonar #1 is completely set up, that is, all of the connections from the servo controller board to the sonar are made (I "borrowed" two team's connectors to do this -- thank you!) However, sonar #1 probably needs longer wires between the sonar and the circuit in order that rotations not pull the protoboard or wires too hard. I would recommend leaving sonar #1 as a guide to the connections (though they are a bit trick to follow).



• For sonars #2-5, you will need to build five more connectors (four if you use your old power connector, if it hasn't been stolen!). It's probably a good idea to give yourself a good amount of wire room (it's easier to trim wires than to extend them!) Here is a picture of the five (a description follows):
  
  These are (3) power connectors like the one you build for the servo motor. In addition, you will need (1) wire attached to one of the pins of a two-pin female header socket. I would use blue to indicate a signal wire. This will carry the echo response from the sonar to the top left pin on the PONTECH board (when you look at it with the word PONTECH at the top left/center). Finally, you will need (1) wire attached to one of the SIDE pins of a three-pin female header socket. Again, I would use blue -- this wire will carry the PWM signal from the EIGHTH servo motor slot to the sonar input (middle sonar wire). This pings the sonar. Take a look at sonar #1 for reference.



• After you've created these connectors, hook them up between the PONTECH board and the circuit as indicated in the following two pictures (a verbal description follows, so you know what's hooking where -- also the yellow manual is on the table if you'd like to confirm or look uo anything...):
  
  
  
  Basically, the three power connectors hook in parallel to the battery pack's power (+, red) and ground (-, black). They go
  • First, to the board's power -- be sure to get + and - correct!
  • Second, to the motors' power -- this is the pair of pins in the lower right-hand corner (when looking at it with the PONTECH at the top left/center) -- be sure to get the + and - correct (I think it's opposite of the board's power! The + is labeled.)
  • Third, to the reference voltage for the sonar input. These are pins 9 and 10 in the manual (9 is + and toward the edge of the board, 10 is - or ground and toward the interior of the board). They are near the board's power pins on the left-hand center of the board. They are three sets of pins below where you will put the signal wire that is bringing the echo response from the sonar and they are aligned perpendicular to the board's power and the motors' power. Be sure to get the + toward the edge of the board and the - (ground) toward the interior of the board.
  If everything seems to be working but the servo motor is not behaving, it could be a power problem: you can use the multimeter to be sure between 5.5 and 6.5 volts are being supplied.
  
  The three-pin female socket header with one wire attached on the side should be attached at servomotor #8. The wire should be on the pin toward the interior of the board, not the pin nearest the edge of the board. (Remember when hooking motors up that the brown wire must go toward the edge of the board -- this is the ground signal; the middle pin is the power, and the left pin -- the one we're using here, is the PWM signal which will ping the sonar.) The wire itself should be placed in the same protoboard row as the sonar input signal -- this should ultimately lead the the middle (#3 out of 5) spot on the lower back of the sonar.
  
  The two-pin female socket header with one wire attached should be attached to A/D pins #1 and #2 (in the manual). Pin #1 is the top-left-most pin on the board (when looking with the PONTECH at the top left/center). The wire itself should be connect to pin #1 and then should lead to the row on the protoboard shared by the resistor and capacitor. This will be the "nicely conditioned" signal back from the sonar echo. You should follow the signal wire from the other end of the resistor to the spot on the sonar right next to the power (+) wire.



• Try it out before mounting it on the robot. The software is available from the software page (it's an update of the old servomotor-driving software, now in client/server form and with sonar-reading capabilities.) Be sure to
  • turn on the power from the batteries before running the server that talks to the board
  • you should hear the ticking of the sonar when you power on if you listen closely
  • turn off the power from the batteries when you're finished running the sonar/servomotor -- it will otherwise continue to draw current, quickly depleting the batteries (and potentially harming the battery holder or circuit)
  
  
  
• Feel free to email me if something here isn't clear or you run into problems. I'll be away until Sunday, but I'll be replying to emails and if something needs physical attention, I should be able to get to it Sunday night. Good luck and happy sonaring!