Blog 15

Working with stepper motor

In this post I am going to connect a stepper motor with my Arduino. I want the stepper motor to turn left and right, and I want the stepper motor to turn a certain degrees.

Before programming I first need to connect the Arduino with the stepper motor.

The hardware I used:

• 7fets
• 28BYJ-48 Stepper Motor

( I also posted in Blog 14, I connected the 7fets with an lcd + display. This is something what of course is not needed )

As you can see in the image is that the stepper Motor has 5 coloured cables, that are all together in a white cube. These cables have to get connected with the 7fets. To do this you have to get 5 male to female cables. From cable blue to orange from the stepper motor it has to be connected to pin 2,4,6,8. The red cable can be put on pin 1, all the other places in the row that are dev power. ( Places where it can gets it's voltage ) ( out 1 till 4 , works different counts 0 till 3) ( in 1 till 4 ) 7FETs

Now the programming part:

I used a script named ardemo_lcd.pde, that I changed to get it working with the stepper motor.

const int SPICLK  = 13;
const int SPIMOSI = 11;
const int SPIMISO = 12;
const int SPISS  = 10;

void SPIinit(void)
{
  pinMode (SPICLK,  OUTPUT);
  pinMode (SPIMOSI, OUTPUT);
  pinMode (SPIMISO, OUTPUT);
  pinMode (SPISS,   OUTPUT);
  digitalWrite (SPISS, 1);
   
  SPCR    =  _BV(SPE) | _BV(MSTR) | _BV(SPR1) | _BV(SPR0);
} 

char SPI(char d) 
{  // send character over SPI
  char received = 0;
  SPDR = d;
  while(!(SPSR & _BV(SPIF)));
  received = SPDR;
  return (received);
} 

void SPI_startpkt (void)
{
 digitalWrite (SPISS, 0);
}

void SPI_endpkt (void) 
{
  digitalWrite (SPISS, 1);
}

void set_var (unsigned char addr, unsigned char a, unsigned char v)
{
  SPI_startpkt ();
  delayMicroseconds (WAIT1);
  SPI (addr);
  delayMicroseconds (WAIT2);
  SPI (a);
  delayMicroseconds (WAIT2);
  SPI (v);
  delayMicroseconds (WAIT2);
  SPI_endpkt ();   
} 

void set_var32 (unsigned char addr, unsigned char a, unsigned long v)
{
  SPI_startpkt ();
  delayMicroseconds (WAIT1);
  SPI (addr);
  delayMicroseconds (WAIT2);
  SPI (a);
  delayMicroseconds (WAIT2);
  SPI (v);
  delayMicroseconds (WAIT2);
  SPI (v>>8);
  delayMicroseconds (WAIT2);
  SPI (v>>16);
  delayMicroseconds (WAIT2);
  SPI (v>>32);
  delayMicroseconds (WAIT2);
  SPI_endpkt ();   
}

static unsigned char spi_7fet_addr = 0x88;

void setup() {
  //declare the motor pins as outputs
  SPIinit ();  
  Serial.begin(9600);
  set_var(0x88, 0x30, 0xff);
}

void loop(){
  set_var32 (0x88, 0x42, 0x50);
  delay(1000); 
}

void setup() {
  //declare the motor pins as outputs
  SPIinit ();  
  Serial.begin(9600);
  set_var(0x88, 0x30, 0xff);
}

void loop(){
  set_var32 (0x88, 0x42, 0x50);
  delay(1000); 
}

This says that at address 0x88 from the 7fets it has to go 50 further from the current position and after that it should take a 1 sec break. ( repeat and repeat itself) 0x42 is for setting the relative position. ( so in the example script it goes 50 further from the current position ) Port 42 is 32bits, don't forget about if a port is 32bits or not. ( On the DIO protocol you can find all the ports. )