PWM in control dc motor speed (Both direction)

[sysysy]

Hi,

I am using 16f877a PIC to control my 2 dc motor via L298 motor driver.(dual channel)

Since 16f877a only got 2 PWM pin, and I've used it for controlling both of my motor speed.

Initially, I use each of the pin to control each of my dc motor speed to running forward. Hence, I have no pins left for controlling the motor speed running reverse.

As we know, we need to set 1 input high and 1 input low to make the motor run.

My question is, can I only use 2 PWM pin but can control 2 of my DC motor speed running forward and backward as well? The concept is when running backward, I make 2 input also high, but one of the input is control by PWM.
Hence, there is a potential different between 2 input and manage to make the moving backward.

When I set my duty cycle for PWM very high, that mean motor will run faster in forward direction but slower in backward direction.

When I set my duty cycle for PWM very low, that mean motor will run slower in forward direction but faster in backward direction.

I try it and it really work. But I just worry is this danger to my circuit or driver?

Hope will get some opinions.

Thanks,

Regards,

sysysy