28BYJ-48.c

#include <Arduino.h>
const int IN1 = 9;
const int IN2 = 10;
const int IN3 = 11;
const int IN4 = 12;
int d_hs[8] = {
	B1000, 
	B1100,
	B0100,
	B0110,
	B0010,
	B0011,
	B0001,
	B1001
};
int i = 0;
void step(int d);
void setup()
{
	pinMode(IN1, OUTPUT);
	pinMode(IN2, OUTPUT);
	pinMode(IN3, OUTPUT);
	pinMode(IN4, OUTPUT);
}
void loop()
{
	step(1);
	delayMicroseconds(900);
}
void step(int d)
{
	i += d;
	if(i > 7) i = 0;
	if(i < 0) i = 7;
	byte b = d_hs[i];
	digitalWrite(IN1, bitRead(b, 0));
	digitalWrite(IN2, bitRead(b, 1));
	digitalWrite(IN3, bitRead(b, 2));
	digitalWrite(IN4, bitRead(b, 3));
}