photoresistor to BOE question (and my robot chassis (pics) and idea) love some

SLUG-1

Im connecting 2 photoresistors in series (to me board of ed) and have bought several assorted radio shack resistor packs.... none of them have a 2k ohm resistor in it...do I have any other options/?/ or will i have to wait to buy a 2k ohm resistor (note: I got just about every other resistor rating on hand). forgive me, I am not very familliar with electronics and im learning as i go. [noparse]:)[/noparse]


im working from the robotics handbook i downloaded (and im wiring as shown there) ! any other methods or any info would be great!

Chapter 6: Light Sensitive Navigation with Photoresistors <B>· Page 195
http://www.parallax.com/Portals/0/Downloads/docs/books/edu/Roboticsv2_2.pdf
</B>

Post Edited (SLUG-1) : 12/23/2008 5:26:50 PM GMT

agfa

Just curious.· Why are using two photoresistors in series?

You should be able to use other resistor values, higher or lower.· It would just change the light level that crosses the input threshold.· you could also use 2 1k resistors in series, or other combinations of resistors.· Total resistance in a series circuit is the sum of the individual resistor values.

SLUG-1

Ahh! thank you! the reason im using them in series is because :

Chapter 6: Light Sensitive Navigation with Photoresistors · Page 195
http://www.parallax.com/Portals/0/Downloads/docs/books/edu/Roboticsv2_2.pdf

and so im learning for the first time how to hook up photoresistors. i would prefer to hook them up individually but if you actually look at how they
are hooked, you will see that each photoresistor is on a different I/o pin . what i would like to know is how i could hook up 5 photoresistors 2 for front 1 for each side and 1 for back!>?

Post Edited (SLUG-1) : 12/22/2008 6:17:24 PM GMT

Justin Ratliff

So on about page 195 it shows 2 photo cells connecting to 2 different I/O pins.· Like agfa said, if you can't find the exact resister value shown, no big deal as long as it's sort of close.· If you are still trying to get a 2K resister you can connect 2 1K resisters in series to get 2K resistance from the 2.

If you want 5 photo cells the best thing to do would be to connect each one up to their own I/O pin on the stamp.·

If you are looking to save your I/O pins used for light detection you could in theory connect the photo sensors in parallal to each others.· I've never done that before, it might provide some strange readings.· And you robot would not know which direction the lights was coming from, only that there was light.

Another alternative would be to mount the light sensor on a servo, like a head or turit for the robot.· Command the servo to turn left, forward, right and to the rear then repeart.· Light measurements could be taken at each location and the robot could determine where a bright light source is.·

Or just turn the robot to find a light source.

Those are a few of the suggestions I have.·

Happy Roboting,
-Justin Ratliff

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Happy Roboting,

-Justin Ratliff
The Robotics Club of Yahoo
https://www.trcy.org

SLUG-1

Perfect.!. i wasnt sure if had to be exact (resistor value). i think ill use 5 i/o pins for the now! 2 in front 1 on each side and 1 for rear, and if i end up needing an I/O pin i could always wire the front 2 in series and leave the other 3 on thier own I/O pins. I want 2 thank you all for being patient with me as i am newb. I guess ill take a second to mention what my robot has/is going to be equipped with.
sensor's:
mesmic accelerometer
5 photoresistors
1 Ping )) w/ servo mount
2IR detectors
and eventually a camera

-im using the BOE bot chassis split down the middle and Bonded to A rectangle of of aluminum and im using a T bracket to mount another smaller rectangle to the back of the top rectangle
making for an interesting chassis design ( basically to make more space for the turret i plan to put on top ). Now im hoping to do a laser range finder w/ camera. ill post some pictures of the
chassis in the next post.

oh and i have a USB Parallax servo controller- im hoping this is a viable option for taking the servo calculations off my Basic Stamp 2 (so it can worry about sensors and such) any feedback would be appreciated!

This is my security bot

Post Edited (SLUG-1) : 12/23/2008 4:58:49 PM GMT

SLUG-1

here are some pictures of my robots chassis (still a work in progress!)

GWJax

another way to control your sensor is by using a A/D chip along with a shift register chip to cut back on your I/O pins but then the programming may be a little bit harder for you at this stage. If you want I can look for a good schematics for you along with some sample code.

Jax

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If a robot has a screw then it must be romoved and hacked into..

SLUG-1

Sure id be interested in seeing some schematics ! Also i am wondering about using the servo controller in robotics appz! will this help take the load of my BS2?

boe-crazy

Cool, I've been thinking about this. What if one were to mount a boe-bot chassis to the back of another chassis with two seperate BOE's (board of education) and have the two work together to accomplish tasks faster and with more accuracy than with just one boe-bot. If you had one with a ping sensor and the other board with a servo controller and treads you could explore narrower spaces. Another one could have a arm instead of treads, and, with the arm you can pick up a object, carry it through a foriegn environment, and then set it down at a pinpoint location.

Ugha

SLUG-1: Great looking chassis... but I'm a little concerned with the weight on your servos. I'd recommend just piling everything you plan to hook up onto the base and hooking it up to run forward,
turn around and go backwards.... see if the servos seem to struggle or not. Might be wise to add an additional pound for future expansions as well.

boe-crazy: I've done something like that, two BOE's and a BS2 OEM on two boe-bot chassis bolted together. Its not quite what you mentioned but it proves its possible.
My thread with pictures: http://forums.parallax.com/forums/default.aspx?f=10&m=311323&g=312570

Please note that the robot doesn't have the second BOE in those pictures and I am working on a tread-based chassis so those images are obsolete.

boe-crazy

THanks!

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To make something work one must build, test, and verify bfore proceding.· -- myself

SLUG-1

ive been thinking that perhaps slightly bigger wheels would b(o)e an asset. Then also was thinking of putting a a free floating wheel for the back (the type shopping carts use.... but im not sure if that would create calculation problems while reversing!?! oh yeah can someone link the address for Looking up I.C.'s!!?? sry i cant remember what it is for the life of me!! [noparse]:)[/noparse] BTW ill put some new pictures up soon im working on a turreted camera w/laser (hope fully for eventual range finding) .
!!! as a first time MCU user U guys really help 2 inspire!





many milllion Thnxses!
Slug-1