The PCB's or just IC's are designed to work with a microcontroller this is normally ByPic, Arduino or Raspberry Pi. They will have an I2C, serial or both interface. A PC can also be used by using a USB to serial or USB to I2C converter depending on which interface is required.
P0 Series (I2C or Serial) These are pre-programmed microcontrollers that can expand the current microcontroller offering or give protection to the existing microcontroller pins.
BV4601 (I2C and Serial) This can be stacked with another or with the motor controllers. This device also has 2 ADC inputs.
Motor Controllers (1A and 4A, I2C and Serial). These can be stacked, suitabe for stepper and DC motors.