SONAR Sensor Software Driver

[B_Dubbs]

Hi team 1153 posting. I would just like to extend a gracious thank you to everyone who helped, as we got our sonar up and running tonight. Now onto new problems. Our Sonar is giving us data in spurts so our Displays look like
Distance = 5
Distance = 0
Distance = 5
Distance = 0
Distance = 5
Distance = 0
Distance = 5
Distance = 0
Distance = 5
Distance = 0
etc.
Does anyone know why t has these jumps to zero? We followed through the code that it seems to be coming from Timer3 being equal to 0 at certain points, but we would like to know if that is the case or what is causing it to go to zero and if possible how to fix this issue. Many thanks team 1153.

[MikeDubreuil]

Originally Posted by B_Dubbs

Distance = 0
Distance = 5
Distance = 0
etc.
Does anyone know why t has these jumps to zero?

You'll need to provide more information for me to understand the problem. Is 5 the correct distance? Where does Ping_Sonar() and Get_Sonar_Distance() get called in your code? I seem to remember while developing the code that many print statements in the code cause bizarre results, watch out for that too.

[Gdeaver]

I know that this discussion is focused on the VEX sonar but, the Matbotix sonar sensor is a much better sensor. It has been redisigned and is offered in several versions with different cones of detection. The nice thing about programming these sonars is that they offer a analog voltage output. A simple A to D call is all that is needed. They are 25$ plus shipping. Check out Sparkfun electronic for the differnt models and some links to FAQ and data sheet. The Sharp IR proximity sensor are similiar to the sonar but, better for some uses.
http://www.sparkfun.com/commerce/cat...hp?cPath=23_84

[Roger]

Unfortunately I didn't grab the code from last night so I don't remember exactly how "B_Dubbs" set it up (and he is hopefully at school right now and can't answer).

Generally it was counting down each loop and at one number it would do the Ping_Sonar() and a (lower) number it would do the Get_Sonar_Distance(). Originally it was 38 and 19, but I was trying to get him to go down to 3 and 1. My reasoning being that the Ping needs time to, er, ping before doing the Get.

We didn't have too many printfs, just printing out the distance and (at one time) printing out the raw number in Get_Sonar_Distance(). The output was pretty regular.

The numbers were approximately the distance, though I was just eye-balling it from afar. I tried to find out how far a distance it could reach but the numbers were only going up to 12 or 14. (I'm hoping for a bigger distance.) When it was working it would alternate a number-distance with a zero.

We are using 2006 (pre-Kevin's PWM routine) code, BTW.

Going back to my DOS days programming with INT 27h, I recall that you can daisy-chain programs to an interrupt address. Thinking ahead to making this code work with 2007 code, can this daisy-chaining work with IFI's code?

Mike, I want to also thank you for your time. I also want to thank you for an opportunity for me (at least) to dive into FRC interrupts -- it looks like fun!

Gdeaver: I'll put your suggestion into the Subcommittee in charge of Acquisitions (Sonars and Sodas sector) We're only using vex sonars as we have a couple from years past.