Hi, I am trying to use the CD4001 NOR gate chip to control the DIR and PWM of a H-bridge so that the motor can run at variable speeds in either direction. I found a very good article about this discussing in detail how this can be done at lamja.com http://www.lamja.com/?p=58. While everything makes sense, I am confused about how to keep the motor stopped. According to the truth table, the PWM would have to be set to 1 for the motor not running. However, when you initially turn on the power, isn't the PWM=0?, which would cause the motor running uncontrolled? Or did I miss something here? Similarly, what happens if the PWM input is lost? Will the motor run out of control?
I thought about adding an invert gate before the PWM input to make it PWM=0 means motor stopped, but I wasn't sure this is the way to do it. Any comments would be greatly appreciated. Thanks!
I thought about adding an invert gate before the PWM input to make it PWM=0 means motor stopped, but I wasn't sure this is the way to do it. Any comments would be greatly appreciated. Thanks!