Let's Make Robots!

IR compound eye

Mr._General_4.bas17.21 KB
Vendor's Description: 

I have posted some tip/walkthroughs on home made IR sensors for obstacle detection and later for motion tracking. Now DAGU proudly presents the IR compound eye. Designed to fit LMR's universal sensor bracket, this sensor works by shinning IR light onto an object and then tracking the reflected IR. This sensor does not work in bright daylight as sunlight has a lot of IR and blinds the sensor.The IR LEDs can be controlled by a digital output so that ambiant light as well as reflected light can be measured. Your microcontroller needs 4 analog inputs available to use this sensor. See a video of it working here: http://www.youtube.com/watch?v=iKYCob7getU

Note: calibration is not normally required, heatshrink is provided fo those who wish to fine tune their eye. A black permanent marker can also be used. Incorrect application can reduce the range of the eye.

This product is now sold at Robot Shop.

Click on the schematic for a bigger image.



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The range that the eye can detect and track an object depends on 2 things.

1- Ambient IR such as daylight will reduce the range. This sensor works best indoors at night.
2- How well an Object reflects IR light. This depends on size and colour of an object.

With Mr. General, the robot can detect my hand from as far as 200mm depending on ambiant light.
When holding a white business card the robot can detect my hand from as far as 300mm.

For fast accurate tracking I program Mr. General to try and stay withing 100mm.

I bought one of these a while back, but still didn't have time to play with it. I hope to hook it up this weekend. But I don't know how to connect it?! I know it takes 4 ADCs and I'm looking at the schematic. However I still don't quite understand this electronics mumbo jumbo so the schematic doesn't make much sense. I don't know what this J1 rectangle is supposed to indicate? I suppose they are the connections (1 x 5V, 4 x ADC and 2 x ground)? But then I'm not sure whether the 4 grounds at the bottom of the schematic are actually the ADC connections?!

Hope to get a few hints :/

Unfortunately I cannot teach you to read a schematic in a post. For a start there is more than one way to draw a schematic. The schematic in this post is fairly international standard which is different to the way I normally draw them on Corel Draw.

Ground is always ground (0V) so no they are never ADC connections.

It ain't your job teaching me to read schematics, but unwillingly you just did anyway :D

Since one can connect 5V directly to an ADC I figured that the ADC is allready grounded so I didn't know. But know I do: Ground is ALWAYS ground!!

Besides after hooking up a couple of QRB1134 sensors recently I actually UNDERSTAND this circuit now (since it's also made from phototransitors and IR LEDs). Besides if I had bothered to open the bag the eye came in, look at the device and read the note that came with it I wouldn't have had to ask those silly questions to begin with. Sorry!

I do however have one thing I would like confirmed before I connect it:

It doesn't say the pin numbers on the board. So I've been trying to figure out which is pin 1 and which is pin 7. I presume that pin 1 is the one where it says J1 (like in the schematic) and pin 7 is the one closer to the PN100 transistor. Is this correct?

Thanks :)

If you look carefully at the pads on the PCB, pin 1 has a square pad where the others are round. The next batch of PCB's should have the pin numbers printed on them. This was an oversite on our part. Be carefull not to apply too much heat when soldering the components as the phototransistors, LEDs and transistor can easily be damaged. If you take more than a second to solder a joint then stop and let it cool before trying again.

The board I got came PRESOLDERED thankfully. I believe I even asked if that was the case before I bought it, because otherwise I probably wouldn't have bought it at all.

And I'm not sure what a "pad" means (excuse my english). I think it means the holes in the PCB for soldering components, but I'm not sure. Either way it doesn't help me determining which is pin 1 and which is pin 7.

If you look at the photo at the top you will see that the copper pad around pin 1 is square. Here is a greyscale photo which might be easier to see it in. My software is playing up at the moment so I can't insert an arrow or anything. Just below LED1 you will see the copper around the hole is square rather than round.



This is off course impossible to see on a soldered board, so thanks for the info. It's opposite of what I thought since I kinda assumed that pin 1 was the one where it says J1, like in the schmatic. Good thing I didn't hook it up yet ;)

J*number* seems to usually just indicates a header. So for that diagram, J1 is the 1x7 row of pins/solder pads/holes/whatever.

The 4 grounds at the bottom should just be grounds.They are likely already tied to the ground of the PCB, common with pin 7 of the header. They shouldn't be connections you have to make.

Pin1 is 5V, or whatever voltage you're running it.

Pins 2-5 (on J1) will be what connects to the ADCs. Looks like pin2 is Q7-Q8, pin3 Q6-Q5, etc...

Pin 6 appears to be the enable for the IR emitters. Looks like if you tie it to ground the IR LEDs stay on, or you can put it to a digital IO on the micro and switch the IR LEDs (turn em off to save power, or not interrupt your Sharp, or whatever)

Pin 7 is ground, which should just tie the other grounds in the diagram together into one point that connects to your micro's ground.

I've had the same questions. I haven't seen a really good pin out for it.