Society of Robots - Robot Forum
Electronics => Electronics => Topic started by: BANE on January 21, 2008, 06:21:14 PM
-
What I'm trying to make is a conveyor belt that can detect an object ether at the front or back. However, I'm trying conserve on the ports used on the microcontroller, so if i can figure out how to make a sensor that sends four signals (nothing detected, front detected, back detected, and both detected). I know this is probably really simple, but if someone could link me to some schematics or some helpful advise that would be most appreciated :).
see the conveyor pic!
bane
-
just dedicate another microcontroller just for deteting the things and have the microcontroller output serial data on one of the pins on the master microcontroller and thats it ,
-
Yes thats what kind of what i had in mind, but what i really need is the schematics for the IR sensor :P
I quickly drew this up, do you think i will work if i have to different resistors for the IR's outputs. I think i can get the microcontroller to distinguish between the voltage difference (2.5 v = no detection, 1 v = front detection, 1.5 v = back detection, and 0 v = both detection)
Sorry if this is terribly incorrect, I'm still pretty new at all of this ;)
bane
-
whooooops!!! forgot to attach the picture!!
bane
-
this is a clearer schematic of what you want
http://www.superdroidrobots.com/product_info/qrb1134.htm (http://www.superdroidrobots.com/product_info/qrb1134.htm)
I think i can get the microcontroller to distinguish between the voltage difference (2.5 v = no detection, 1 v = front detection, 1.5 v = back detection, and 0 v = both detection)
You want an analog output from your microcontroller , I believe you can use PWM to do analog output , just like speed control.
I personally always did serial data, thats extremely easy to do . Ill take a look into analog outputs . You are using C on an AVR , right
EDIT: found the link on doing analog outputs ,and it does use PWM like I thought . http://www.tigoe.net/pcomp/analogout.shtml (http://www.tigoe.net/pcomp/analogout.shtml)
-
Sorry, im not sure what you mean by this
you are using C on an AVR , right
But i assume that "C" is the programming languge and AVR is the microcontroller?
I will be using LynxTerm as the programming program (in the mailing process) so what every that uses (assuming C) and i will be using Lynxmotions mini ABB BS2.
Just a question, is there anything wrong will the schamatics that I drew up??
bane
-
you assumed correctly and your schematic was correct , just you layed it out in an unorganized fashion
you should spread out your components and also have the power wire be a horizontal wire , makes it easier for the eyes
also you only needed schematic for one sensor , since the other 4 were copies
mailing process, what do you mean?
-
There are 2 IR emitters and 2 IR receivers and I only drew them that way because thats the way it will look on the conveyor system (sorry, helps me see what I'm doing :D) I don't have the microcontroller right now, but ordered it two days ago, so i assumed its in the mailing process :D.
I haven't considered this but what type of resistors (amount of resistance) should I use so that the signal is strong yet a major difference in the microcontrollers readings is still shown?
bane
-
Easy . . . wire both IR receivers in series . . .
5V --- IR1 --- IR2 --- Vout --- resistor --- ground
Now, use two different types of IR - not the same model or sensitivity!
So IR1 might cause a 2V shift, while IR2 might only cause a 1V shift. You'd have to check datasheets to do this . . .
0V shift - nothing happened
2V shift - IR1 was blocked
3V shift - both IR's were blocked
1V shift - IR2 was blocked
-
couldn't you just use two diff. resistors for a diverse signal? I'm not quite sure about how to make the IR sensors in series (maybe some schematics ;) please if your time premites) And why did you call it a "shift" in voltage and what would be your nominal voltage? Couldn't you program the controller to look for a series of voltage ranges? Another thing, when you see a signal and its just a big number, i know that the frequencies are but if its just voltage? (I only have used the Parralax Sumo Bot board and thats what it does, not sure about others)
bane
-
its really not as hard as it sounds . . . replicate my above circuit using two different types of IR sensors, attach Vout to an ADC pin on your microcontroller, program and IF->Then loop, and you are done.
I only have used the Parralax Sumo Bot board and thats what it does, not sure about others
hmmmm problem . . . the parallax sumo board does not have an analog to digital converter, meaning each of your pins are only capable of two digital states - not four like you want. You will have to use two pins (for four states) if you want to use that board.