LOW command and a Motor driver Problem

Andy B

hi again guys..

i bought this motor driver
http://www.hvwtech.com/products_view.asp?CatID=113&SubCatID=146&SubSubCatID=0&ProductID=30

as you will see,there is a common ground which is connected to the stamp VSS
to control Forward and backward of each motor you send a LOW command.

I:E
Left_F·· PIN 0
Right_F· PIN 1
LEFT_R··PIN 2
Right_R· PIN 3
LOW 0 and LOW 1 to drive both motors forward, connected to the pins on the L298
my problem is:
when i give it a LOW 2 or LOW 3, the motors freeze, because it hasnt turned off LOW 0 and LOW 1 and is trying to go forwards and backwards at the same time.

Forgive my Stupidity but is there a way to turn off the LOW to that pin? rather than sending a HIGH.
As i am not sure and NOT brave enought to send a HIGH incase i blow the Stamp or Controller.
or should i be using another command to turn it off? ... Making it neither High or Low?

All the help i can get will be greatly appreciated, i'm a very Newbie to robotics

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Prone to outbursts of ultimate creativity and weird interests

Post Edited (Andy : 7/16/2006 4:36:14 AM GMT

Andy B

i think i found a solution:

alloff:
DIRS = %0000000000000000
return

it seems to turn them off, hope i'm right lol

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Prone to outbursts of ultimate creativity and weird interests

Franklin

tie a resistor from the pin to vdd then when you set the pin high it won't be low but it will not have enough power to damage anything. There are examples of this around but I couldn't find any at this time.

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- Stephen

Andy B

Thank you stephen, i'll give that a try also and see what works best

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Prone to outbursts of ultimate creativity and weird interests

Beau Schwabe

By the looks of the L298 datasheet on page 1, it appears that there is logic
protection that prevents the H-Bridge from self destruction.
http://www.tecel.com/data/l298.pdf

In other words, when BOTH inputs (Fwd or Back) are the same either both HIGH
or both LOW, you have an electronic braking effect from the motor.

Aside from that the "motor Kit" already has 10K current limiting resistors on
the inputs.


Seems like what you want to do is "Disable" the motors.· I would pay attention
to the "Enable" pin... The documentation says...

"[color=red]The Enable connection is an active LOW[/color] connection that is pulled HIGH for 
you on the circuit board. Ground this connection to disable a motor. Note: 
While disabled, commands from the host microcontroller will have no effect on 
that motor"

...It should say "The Enable connection is an active HIGH..."· ...either way,
making this pin LOW should disable the motor(s).· If you need separate control
for each motor, then you will need 2 I/O's (One on each motor). If both motors
can be enabled/disabled at the same time then you will only need 1 I/O. ( Tie
both Enables on the motor controller kit together. )

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Beau Schwabe

IC Layout Engineer
Parallax, Inc.

Andy B

I thought there was something wrong with the instructions that came with it..
Many thanks BEAU i will give that a try tonight

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Prone to outbursts of ultimate creativity and weird interests