Personal range finder

With this project I focused on making an affordable personal range finder as an assistive device.

The tricky part to using the srf series range finder with the arduino is the I2c bus interface it is a fairly straightforward protocol (a good reference is at http://www.robot-electronics.co.uk/htm/using_the_i2c_bus.htm) but would take a lot of typing if you did it from scratch. It is basically a handshake method where the arduino slaves the srf range finder to its clock pulses and tells it when and from where the rangefinder will send information. It sends out info on the leading edge of the clock pulse and receives it on the falling edge, but the signals state (bit passing) never changes while the clock state is high, except to signal a start or stop to a communication. So the easiest way to communicate with your range finder is to use the code found on the Wiring web site (it is the sibling of arduino but even more user friendly it seems) and use the “wire” library (here’s the link http://wiring.org.co/reference/libraries/Wire/index.html). I took that code and modified it to include changing the address, the sensitivity and the range settings for the srf range finder (it should be talked about although maybe a bit muddled in the pamphlet that comes with the range finder). Also be sure to use the arduino 06 platform when implementing the library or it won’t compile, that was a big problem for me. So either use the code on the Wiring web site or take a look at mine (in the extended entry along with the pins to use) I hope this helps. Good luck!
Ps it took me a really long time to do the water colors so i hope you enjoy them.

I had many hours working with these guys especially the srf10 in the above picture; I had to learn about the I2c bus communication to get it running. I did find code for it finally on the wiring website there is code from the wire. class that makes bus communication a snap but you have to down load the arduino 06 if you want to call the class in arduino. the other sensor the sense ez is a real plug and play sensor and the focal area of the sound cone is very narrow and really accurate i can't recommend this sensor enough. i will post the code when i finish writing it but it is very simple to use. the srf10 has a much bigger range but it detects anything in a 180 degree sweep from center up to three feet on the sides and below it so you have to either really point it up or raise it three feet off the ground. not so good for my application.

i got the servo working finally, although i couldn't get the port addressing to work from tom igoes code example. just allot of repeat typing. it runs off of 12 volts and sinks about 250mA under a load so if i use a battery it won't be running for that long. ill have to think about that i am using a hbridge right now i can't decide if i need the enable pin or if i should switch to a darlington array for easier wiring.

Here are some basic "circuits" I used to function as switches for ac current controlled by the arduino. The arduino puts power to a transistor, which controls the relays. The resistors are used to drop the base voltage because the transistors need a good voltage differential between base and emitter to operate.