TB67S109AFTG stepper driver test code

/*
   Scott Beasley - 2020
   This is a test program for the cheap knockoff TB67S109AFTG
   stepper driver boards that pose as TB6600 drivers. These drivers
   have an issue with losing or gaining steps.  The ones I have tested
   have step issues whilst changing direction. The move following the
   direction change will lose/gain steps.  I have noticed as well that
   the pulse delay needs to change as the current is set to a higher
   selection on the driver.   The driver also will only output no more
   than 1.2amps per my testing.  Your mileage may vary.

   UPDATE:
   The issue may be with the ENA function of the chip being slow to change
   state.  If I enable the driver and leave it that way, no steps seem to be
   lost.
*/

// Direct io macros.
#define SET_BIT(p,n) ((p) |= (1 << (n)))
#define CLR_BIT(p,n) ((p) &= (~(1) << (n)))
#define TOGGLE_BIT(p,n) ((p) ^= ((1) << (n)))

// Arduino pins
#define STEPPIN 12   // Connected to the PUL + on driver
#define DIRPIN 6     // Connected to the DIR + on the driver
#define ENAPIN 10    // Connected to the ENA + on the driver
// DIR -, PUL - and ENA - are connected to the Arduino GND

// 328p ports
#define STEP_OUT PB4
#define DIR_OUT PD6
#define ENA_OUT PB2

// Globals
//const int PULSEDELAY = 750; // Delay for 0.5-0.7a
const int PULSEDELAY = 850; // Delay for 1-1.2a
//const int PULSEDELAY = 450; // Pulse delay for current setting of 1.5-1.7a

void setup() {
  // put your setup code here, to run once:
  pinMode(STEPPIN,OUTPUT);
  pinMode(DIRPIN,OUTPUT);
  pinMode(ENAPIN,OUTPUT);
  SET_BIT (PORTB, ENA_OUT);
}

void loop() {
  forward(200);
  delay(500);
  forward(200);
  delay(500);
  TOGGLE_BIT (PORTD, DIR_OUT); //SET DIRECTION
  reverse(400);
  delay(1000);
  TOGGLE_BIT (PORTD, DIR_OUT); //REVERSE DIRECTION
}

void pulse (void) {
    SET_BIT (PORTB, STEP_OUT);
    delayMicroseconds(PULSEDELAY);
    CLR_BIT (PORTB, STEP_OUT);
    delayMicroseconds(PULSEDELAY);
}

void forward(int steps){
  for(int i=0;i<steps;i++){
      pulse ();
  }
}

void reverse(int steps){
  for(int i=0;i<steps;i++){
      pulse ();
  }
}