The Arduino sends serial data to the 74HC595 chip. The chip "expands" this data into 8 outputs, which feed into the Input pins of the L293D drivers.
Two L293D chips, each containing four H-bridges. hw 130 motor control shield for arduino datasheet better
| Shield Function | Arduino Pin | |----------------|-------------| | direction | Digital 12 | | Motor A PWM speed | Digital 3 | | Motor B direction | Digital 13 | | Motor B PWM speed | Digital 11 | | Servo 1 signal | Digital 9 | | Servo 2 signal | Digital 10 | | Enable A (jumper) | Digital 6 (if removed, else always on) | | Enable B (jumper) | Digital 5 (if removed, else always on) | | External power (VS) | Screw terminal “EXT_PWR” | The Arduino sends serial data to the 74HC595 chip
// HW-130 Motor Shield Pin Definitions #define ENA 9 // Speed Motor A #define IN1 4 // Direction Motor A #define IN2 5 // Direction Motor A each containing four H-bridges.