// for linear pipette stepper

// wire color | hbridge output | 
// black | 1 | B2
// red | 2 | A2
// purple | 3 | B1  
// grey | 4 | A1

#include <avr/io.h>
#include <util/delay.h>

#define output(directions,pin) (directions |= pin) // set port direction for output
#define set(port,pin) (port |= pin) // set port pin
#define clear(port,pin) (port &= (~pin)) // clear port pin
#define pin_test(pins,pin) (pins & pin) // test for port pin
#define bit_test(byte,bit) (byte & (1 << bit)) // test for bit set

#define bridge_port PORTA // H-bridge port
#define bridge_direction DDRA // H-bridge direction
#define A2 (1 << PA1) // Grey 
#define A1 (1 << PA4) // Purple 
#define B2 (1 << PA3) // Black = 1
#define B1 (1 << PA0) // Red = 2
#define on_delay() _delay_us(1500) // PWM on time
#define off_delay() _delay_us(500) // PWM off time
#define PWM_count 5 // number of PWM cycles

static uint8_t count;

//
// A+ B+ PWM pulse
//
void pulse_ApBp() {
  set(bridge_port, A2);
  set(bridge_port, B2);
  clear(bridge_port, A1);
  clear(bridge_port, B1);
   for (count = 0; count < PWM_count; ++count) {
      clear(bridge_port, A1);
      clear(bridge_port, B1);
      on_delay();
      set(bridge_port, A1);
      set(bridge_port, B1);
      off_delay();
      }
   }
//
// A+ B- PWM pulse
//
void pulse_ApBm() {
  set(bridge_port, A2);
  set(bridge_port, B1);
  clear(bridge_port, A1);
  clear(bridge_port, B2);
   for (count = 0; count < PWM_count; ++count) {
      clear(bridge_port, A1);
      clear(bridge_port, B2);
      on_delay();
      set(bridge_port, A1);
      set(bridge_port, B2);
      off_delay();
      }
   }
//
// A- B+ PWM pulse
//
void pulse_AmBp() {
  set(bridge_port, A1);
  set(bridge_port, B2);
  clear(bridge_port, A2);
  clear(bridge_port, B1);
   for (count = 0; count < PWM_count; ++count) {
      clear(bridge_port, A2);
      clear(bridge_port, B1);
      on_delay();
      set(bridge_port, A2);
      set(bridge_port, B1);
      off_delay();
      }
   }
//
// A- B- PWM pulse
//
void pulse_AmBm() {
  set(bridge_port, A1);
  set(bridge_port, B1);
  clear(bridge_port, A2);
  clear(bridge_port, B2);
   for (count = 0; count < PWM_count; ++count) {
      clear(bridge_port, A2);
      clear(bridge_port, B2);
      on_delay();
      set(bridge_port, A2);
      set(bridge_port, B2);
      off_delay();
      }
   }
//
// clockwise step
//
void step_cw() {
   pulse_ApBp();
   pulse_AmBp();
   pulse_AmBm();
   pulse_ApBm();
   }
//
// counter-clockwise step
//
void step_ccw() {
   pulse_ApBm();
   pulse_AmBm();
   pulse_AmBp();
   pulse_ApBp();
   }

int main(void) {
   //
   // main
   //
   static uint8_t i;
   //
   // clear clock divider to /1
   //
   CLKPR = (1 << CLKPCE);
   CLKPR = (0 << CLKPS3) | (0 << CLKPS2) | (0 << CLKPS1) | (0 << CLKPS0);
   //
   // initialize bridge pins
   //
   set(bridge_port, A1);
   output(bridge_direction, A1);
   set(bridge_port, A2);
   output(bridge_direction, A2);
   set(bridge_port, B1);
   output(bridge_direction, B1);
   set(bridge_port, B2);
   output(bridge_direction, B2);
   //
   // main loop
   //
   while(1){
       for(i=0;i<50;i++) {
            step_cw();
        }
        for(i=0;i<50;i++) {
             step_ccw();
         }
    }
}