//
//
// net-bi-stepper.ino
//
// bipolar stepper, controlled via serial with Procesing
//
// Original Neil Gershenfeld
// 11/21/12

// Modified Mauro Herrero - Fab Academy 2021

// (c) Massachusetts Institute of Technology 2012
// This work may be reproduced, modified, distributed,
// performed, and displayed for any purpose. Copyright is
// retained and must be preserved. The work is provided
// as is; no warranty is provided, and users accept all 
// liability.
//

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

#include <SoftwareSerial.h> //include SofwareSeriallibrary
SoftwareSerial mySerial = SoftwareSerial(9,10); //define Rx, Tx pins - the unofficial arduino & ATTiny pinout by www.pighixxx.com
float val; // declare char variable to store data received from serial port

//#define is used to define macros, as a non-function text - the name is
#define output(directions,pin) (directions |= pin) // set port direction for output - |=  --> bitwise operator OR
#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 << PA0) // H-bridge output pins
#define A1 (1 << PA1) // "
#define B2 (1 << PA3) // "
#define B1 (1 << PA4) // "
#define on_delay() _delay_us(25) // PWM on time - changing these two, can you vary the output voltage?
#define off_delay() _delay_us(5) // PWM off time
#define PWM_count 50 // number of PWM cycles - number of PWM per step - can rpm be modified?
#define step_count 50 // number of steps - why ~50 per turn? Stepper data sheet stablishes 200 (1.8 deg)

static uint8_t count; //static unsigned integer 8 bits (byte) variable

//
// A+ B+ PWM pulse
//
void pulse_ApBp() {
  clear(bridge_port, A2);
  clear(bridge_port, B2);
  set(bridge_port, A1);
  set(bridge_port, B1);
   for (count = 0; count < PWM_count; ++count) {  //from 0 to PWM_count
      set(bridge_port, A1);
      set(bridge_port, B1);
      on_delay();
      clear(bridge_port, A1);
      clear(bridge_port, B1);
      off_delay();
      }
   }
//
// A+ B- PWM pulse
//
void pulse_ApBm() {
  clear(bridge_port, A2);
  clear(bridge_port, B1);
  set(bridge_port, A1);
  set(bridge_port, B2);
   for (count = 0; count < PWM_count; ++count) {
      set(bridge_port, A1);
      set(bridge_port, B2);
      on_delay();
      clear(bridge_port, A1);
      clear(bridge_port, B2);
      off_delay();
      }
   }
//
// A- B+ PWM pulse
//
void pulse_AmBp() {
  clear(bridge_port, A1);
  clear(bridge_port, B2);
  set(bridge_port, A2);
  set(bridge_port, B1);
   for (count = 0; count < PWM_count; ++count) {
      set(bridge_port, A2);
      set(bridge_port, B1);
      on_delay();
      clear(bridge_port, A2);
      clear(bridge_port, B1);
      off_delay();
      }
   }
//
// A- B- PWM pulse
//
void pulse_AmBm() {
  clear(bridge_port, A1);
  clear(bridge_port, B1);
  set(bridge_port, A2);
  set(bridge_port, B2);
   for (count = 0; count < PWM_count; ++count) {
      set(bridge_port, A2);
      set(bridge_port, B2);
      on_delay();
      clear(bridge_port, A2);
      clear(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();
   }
   
void setup(){
  pinMode(9,INPUT);
pinMode(10,OUTPUT);
mySerial.begin(9600);
  //
   // main
   //
   static uint8_t i,j;
   //
   // set clock divider to /1
   //
   CLKPR = (1 << CLKPCE);
   CLKPR = (0 << CLKPS3) | (0 << CLKPS2) | (0 << CLKPS1) | (0 << CLKPS0);
   //
   // initialize bridge pins
   //
   clear(bridge_port, A1);
   output(bridge_direction, A1);
   clear(bridge_port, A2);
   output(bridge_direction, A2);
   clear(bridge_port, B1);
   output(bridge_direction, B1);
   clear(bridge_port, B2);
   output(bridge_direction, B2);
}


void loop(){
     if (mySerial.available()>0){
      mySerial.read();
     }
     val = mySerial.read();    //read it and store in val
    if(val=='a'){
      for (int i=0; i<step_count; ++i) {
        step_cw();  
      }  
    }   
   }