extras i/o for basic stamp2

dimitrizmech

hi, i am dimitriz and i am working with the basic stamp2, on a robotic arm project.

i have a problem and i want your hepl.
the problem is that i have a 6dof manipulator arm, this means 6 servo motor, (3 analog and 4 digital). so initially i want to work with buttons for the right and left motion of each motor, this means that i have 2buttons x 6motors=12 inputs and 6 outputs for the servos, so i want totally 18 in/out, but i have only 16i/o.

Please do you suggest me to do anything

thanks and sorry for my english

dimitriz

stamptrol

dimitri,

You can multiplex some of your inputs or outputs so that a few stamp pins can read or write a greater number of real-world signals.

For example two 4066 analog mux chips will let 5 stamp pins read 8 field inputs. Or, a 74595 serial mux chip lets 8 field outputs be controlled with 3 stamp pins.

I've used these techniques to use 32 i/o on a single stamp.

Cheers,

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Tom Sisk

http://www.siskconsult.com
·

dimitrizmech

thanks stamptrol....

.....but how easy is to ''give'' me a schematic example, about the connections of these elements.

i mean how i will connect the above elements:
a) button
b) servo
c) basic
d) 74595
between them.

sorry again but now i am doing some steps in electronic

thanks
dimitriz

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Bill Chennault

dimitriz--

Download this Parallax manual (it is free). On pages 130 and 137 it will tell you how to expand outputs and inputs using a Stamp . . .

StampWorks

Have fun!

--Bill

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You are what you write.

stamptrol

dimitriz,

I would concur with Bill C., his reference gives you everything you need.

Cheers,

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Tom Sisk

http://www.siskconsult.com
·

dimitrizmech

thanks a lot, both of you!!!!

i will begin to read it immediately.

thanks again!!!

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dimitrizmech

hi..again

i take the 74hc595 and i am trying to program the basic stamp, but i have a problem.
i read the stamp works, but i do not unterstand, how can i program 6outs from the 74hc595, to transmit pulse for each servo separately.
for example:





i waiting for your answer...

thanks

dimitriz

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Phil Pilgrim (PhiPi)

The 74HC595 would be inappropriate for outputting servo pulses. It would be better to multiplex your inputs and output your servo pulses directly from the BASIC Stamp.

Another option would be to use Parallax ServoPALs to control your servos. Although each servoPAL has two I/O pins, only one is needed to control two servos. So you can control six servos with three pins. In addition, the ServoPALs will keep pulsing the motors while the BASIC Stamp is busy tending to other tasks. The ServoPAL is programmed using the same pulses you would normally send to a servo motor.

For controlling that many motors, a less expensive option is the Parallax Servo Controller. It requires a single pin and can control up to 16 servos. Like the ServoPAL, it will keep pulsing the motors without further intervention. The Servo Controller is programmed via a serial I/O protocol.

-Phil

Post Edited (Phil Pilgrim (PhiPi)) : 1/22/2008 10:46:34 AM GMT

dimitrizmech

phil are you sure because the other two members stamptrol and Bill Chennault, told me that this is possible....with 74hc595 or 74hc165. so the problem is that i don't now the solution and i confused.

phil, please help me, so if you know any mode, that i can programmed basic with the above chips for the servo control , tell me; i do not want to give much more money for the Servo Controller.


thanks a lot

dimitriz

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stamptrol

Dimitriz,

Going back to your original post, you wanted 12 inputs and 6 outputs.

Use the techniques we pointed out to take care of the inputs then use the Stamp pins to drive the servos.

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Tom Sisk

http://www.siskconsult.com
·

Phil Pilgrim (PhiPi)

Dimitriz,

The reason the 74HC595 is not a good choice for outputting pulses is that having to shift the data in each time you want to turn a pin on or off would prevent you from getting accurate pulse widths. That's why it's better either to drive the motors directly or to make use of a peripheral device (e.g. Parallax Servo Controller) designed for the purpose.

Here is an article that describes how to muliplex switches with a 74HC165. It's from the StampWorks manual that Bill recommended.

-Phil

dimitrizmech

stamptrol thanks again.....

can i ask something about 74hc165?

the manual, refered to programming of 8inputs, switches.
if i want to program, 2 separately buttons to control 1 servo from the basic stamp, how can i program that.

if it is easy, can you help me with a simple part of code?

thanks a lot

dimitriz

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stamptrol

·· This is from the StampWorks experiments.

·· It will give you 16 inputs and drive 6 servos and still have spare pins.

·· You read the inputs (as shown in the sample program in the StampWorks). You assign each input to be one of your switches which will command the servos.



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Tom Sisk

http://www.siskconsult.com

dimitrizmech

stamptrol, for an other time, thanks again !!!

best regards!

dimitriz

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