Distance Measurement

Help & Support Robot Parts
1

Hi:

I am looking for advice on which sensor or type of sensor would be my best choice.

I want to accurately measure distances that will range between perhaps an inch to less than a foot.

I have been looking at the Devantech SRF235 because of the focused beam.

I will be interfacing to a microcontroller so I can go either i2c or ADC.

I did like the idea of interfacing from I2C to USB so I could do my initial testing straight on my PC.

Any suggestions welcome

Thanks

TimV

2

Hi Jonathan:

Thanks for the quick reply.

Given the USB aspect, is there software that I can play with from Windows to test the sensor out?

Thanks

Tim

3

Thanks!

I ordered and received an Arduino Diecimila as well as an I2C-IT IR Rangefinder.

I downloaded an application for this configuration from HVWTechnologies. They have a .PDE file that is supposed to be for this sensor since it comes from them.

I can download the code to the Arduino and the program runs but the only result I ever see is the number 1. There are supposed to be a number of set up options for selecting the output format (cm, value or Inches) but their code has no descriptions.

I downloaded the manual from here at RobotShop.ca and it is mostly useless. I also downloaded the zip folder which contains code, but there is a hex version and a C version but no PDE that the Arduino software can read.

Nowhere have I found the address information that is supposed to be called to read the data from - if I need it. I know that the device ID is x20 and that is about all.

I need help to either find more information or understand how to get the C code downloaded to the Arduino.

I am brand new to the Arduino but I have worked quite a bit with Pic Micro. That was all assembler and I have no real C knowledge.

Where do I start?

Thanks very much

Tim

4

Hi and FYI

I have spent the weekend with this sensor and now have it actually supplying readings. The document that comes with the sensor says that the device address is 0x20. It can be changed by soldering across some jumper pads. I did not do that.

It turns out that the device address on my unit is 0x22.

I would still like to know how to set this to see the voltage readings as there is no scale for the distances that it is reporting. They are not inches or centimeters. Yes, I could build a conversion table between what it is returning and whatever scale I want, but avoiding that was the reason for buying the I2C-IT in the first place.

I have sent off a note to HVWTechnologies to see about changing settings. It might in handled in the Arduino library so we shall see where that leads.

Tim

5

Hi:

Thanks for the response. I have received information from the folks at HVWTech that was most helpful.

By default, the unit ships configured to read inches. This code is from the I2C-IT sketch. Changing the Wire.Send(x) x number will set the device as indicated below.

It should be noted that the device will only return whole numbers.

Inches = 1
Cm = 2
Raw = 3
in the section of code that sends to the I2C-IT.

Wire.beginTransmission(deviceaddress);
Wire.send(1);

I hope that this helps others who follow along this path.

I am considering this post closed unless someone can recommend a sensor that will provide a better level of resolution.

Thanks

TimV

6

Hello TimV, welcome to the RobotShop Community.

An approach that may interest you would be to use the Devantech USB to I2C module (RB-Dev-17) in combination with a Solarbotics I2C-IT Infrared Rangefinder (RB-Sbo-47).

7

You can dowload Arduino code examples for the I2C-IT to get you started.

8

You could use Hyperterminal (it comes with Windows).