Control Motors from cmd_vel directly [closed]

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I have a program set up in which I can control all motors pwm and their directions from C code using sysfs. I also have an online dashboard from which I can publish cmd_vel messages with which I wish to control the device movement. I cannot seem to find any examples of combing a C program directly changing header pins with a ROS program handling the Twist messages.

Is there such examples which I can look into using? I need to control the header pins directly and using an extra component such as an arduino is not an option.