Question about PWM vs. high/low signal

Blake

I am trying to find a high power (10amp continuous) dual H-bridge to control to drive motors (both going forward and reverse). I found one out of India that had four pins, and depending on which pin was driven high, motor 1 went forward or reverse, and motor 2 went forward or reverse. Very simple and what i need. Yet all the H-bridges I see from companies in North America seem to use PWM.

For instance, Robotics Connection has a 10 amp dual H-bridge on this link:
www.roboticsconnection.com/p-77-10-amp-dual-h-bridge.aspx

which uses high/low for direction, and PWM for speed. I would be fine if my motors were full on or full off without speed control.

My question is this: Can I apply a on/off (0V or 5V) constant signal to a PWM pin and achieve a full on or full off state? Or does a PWM pin, even in a full on state, require the on/off switching frequency? I have a feeling these H-bridges accept PWM because they are meant to be used with a PWM motor controller delivering them signal. But are there any off-the-shelf dual high-power H-bridges that will work with on/off signals from a basic stamp for example.

I know this is a simple question, thanks for the help.

Blake

Franklin

Looks to me like you could do what you want with that controller.

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- Stephen

Mike Green

There are two ways to design an H-bridge with two input signals. In one case, there's a direction pin and an on/off pin. In the other case, there's a "go forward" pin and a "go backward" pin. PWM is just a scheme to vary the speed by turning the motor on and off rapidly with the motor speed proportional to the average on/off time. If the "on" signal is on all the time, the motor goes at full speed. If the "on" signal is off all the time, the motor stops.