Larger Motor Controller

musictech

I am looking for a way to control nine motors on a robot using one or two stamps.· I am familiar with the Pololu motor controller but it only supports 2 motors.· I need something similar or a circuit that will do the same thing only cheaper than buying 5 pololu controllers.

Here·is the motor:

http://www.solarbotics.com/products/index.php?scdfa-250100084-viewDetail-productzq345zq4categoryzq37=true

Paul Baker

how about using the L293D as the basis of an H bridge, the site you pointed to sells them for $4.95 (great site btw, but they're a bit overpriced in many of thier items, so I think you can find a better price for the L293 elsewhere), then configure as shown in this document: http://downloads.solarbotics.com/PDF/kit10.pdf
use the last diagram on page 10, set stamp for output, logic level controls direction, set stamp to input stops the motor.

Quick confirmation, yeah www.mouser.com sells them for two bucks a pop, less than half the price.



Post Edited (Paul Baker) : 3/24/2005 8:27:19 PM GMT

Jonb

I recently built a dual H-bridge controller based on this one: http://www.dprg.org/projects/1998-04a/, it turned out well after a few modifications to suit my needs. It uses the L298 as opposed to the L293.

You could easily make a custom controller board.

Post Edited (Jonb) : 3/25/2005 4:37:05 AM GMT

LoopyByteloose

If you look into BEAM robotics, you can make several very very cheap H-bridges from six transistors and a couple of resistors. There are even some refinements of adding a pair of diodes and a few resistors inorder to conserve power. (from a guy named "Wilf").

The designs are all 'free form'. That means that they do not need a circuit board for mechanical support. It doesn't get any cheaper or smaller.

Also your supplier - Solarbotics - has a twin motor driver that is powered by a L298 on a 1 and 1/2 inch square circuit board. It is cheap and complete (at less than $20USD) while allowing you to later salvage the board for another project if you heart desires.

The L298 really is a powerhouse and doesn't add significant cost. Skip the L293 as you may later want to move up to more muscle.

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G. Herzog in Taiwan

musictech

Well I ordered the L293D Motor Controllers, and they work fine (thanks Paul). However, now I am trying to solve another issue. There are nine motors on my project and with the motor controller requiring 3 inputs per motor, that is 27 inputs (or 2 stamps). Can anyone think of a way that I could drive 1 motor with 1 pin? So that I only have to use 1 stamp per robot?

Paul Baker

Actually you could control all the motors via 3 lines using 4 74HC595's cascaded. The '595 is a shift register. The first '595 is connected to the stamp through SCK (pin 11), SI (pin 14) and RCK (pin 12), each successive '595 has the SI pin connected to the QH' pin of the previous '595 and the SCK and RCK of each '595 are tied·to the first '595's SCK and RCK.

The spec sheet for the '595 is here http://www.toshiba.com/taec/components/Datasheet/TC74HC595DS.pdf

To transmit data to the motor controllers you place the values on SI and pulse the SCK, doing this 27 times. When your done you pulse RCK and the values you shifted through the registers are updated to the outputs of the '595s.

The timing diagram for this is on page 2 of the spec sheet.

Post Edited (Paul Baker) : 4/20/2005 3:52:15 PM GMT

musictech

Thanks again Paul.· I may need a bit more help with this one, but it sounds like it will be much easier than what I am doing.

Paul Baker

No prob, just pipe up if you need additional help.