[SOLVED] SPI init on ATMEGA128 ?

[bianchi77]

Guys

Do I make a correct SPI init on ATMEGA128 ?
My clock is 16Mhz,
what's the clock for SPI (SCK) ?

Code:

void spi_init(void)
{
SPCR = 0x52; //setup SPI: Master mode, MSB first, SCK phase low, SCK idle low
SPSR = 0x00;
}

Thank you

 

[very question]

Hi
In your example SCK frequency is 16Mhz/64=250Khz

 

[Bluestar88]

Hello guys,
I am trying to initialize SPI interface on Atmega128. My code is here. But when I see SCK pin with Oscilloscope I don't have any pulse..Only there is a line with 1 volt amplitude ....Why? I think I should see a pulse with 1Mhz on SCK.....Please help me...Is there any problem on my code (I also activate usart1 on atmega128 which works correctly)?

#include <mega128a.h>
#include <delay.h>
#define ChipSelectAd PORTB.0

#ifndef RXB8
#define RXB8 1
#endif

#ifndef TXB8
#define TXB8 0
#endif

#ifndef UPE
#define UPE 2
#endif

#ifndef DOR
#define DOR 3
#endif

#ifndef FE
#define FE 4
#endif

#ifndef UDRE
#define UDRE 5
#endif

#ifndef RXC
#define RXC 7
#endif

#define FRAMING_ERROR (1<<FE)
#define PARITY_ERROR (1<<UPE)
#define DATA_OVERRUN (1<<DOR)
#define DATA_REGISTER_EMPTY (1<<UDRE)
#define RX_COMPLETE (1<<RXC)

// Get a character from the USART1 Receiver
#pragma used+
char getchar1(void)
{
char status,data;
while (1)
      {
      while (((status=UCSR1A) & RX_COMPLETE)==0);
      data=UDR1;
      if ((status & (FRAMING_ERROR | PARITY_ERROR | DATA_OVERRUN))==0)
         return data;
      }
}
#pragma used-

// Write a character to the USART1 Transmitter
#pragma used+
void putchar1(char c)
{
while ((UCSR1A & DATA_REGISTER_EMPTY)==0);
UDR1=c;
}
#pragma used-


// SPI functions
#include <spi.h>

// Declare your global variables here

void SPI_MasterInit(void)
{
	// Set MOSI and SCK and SS output, all others input
	              PORTB=0x00;
                   DDRB=0x07; 
                  // SPI initialization
                 // SPI Type: Master
                 // SPI Clock Rate: 1000.000 kHz
                 // SPI Clock Phase: Cycle Start
                 // SPI Clock Polarity: Low
                 // SPI Data Order: MSB First
                 SPCR=0x50;
                 SPSR=0x00;
 }



void SPI_MasterTransmit(char cData)
{
	// Start transmission
	SPDR = cData;

	//PORTC=SPDR;// JUST CHECKING!

	// Wait for transmission complete
	while(!(SPSR & (1<<SPIF)));
}



void main(void)
{

unsigned char a;


// Port B initialization
// Func7=In Func6=In Func5=In Func4=In Func3=In Func2=In Func1=In Func0=In 
// State7=T State6=T State5=T State4=T State3=T State2=T State1=T State0=T 
PORTB=0x00;
DDRB=0x00;

// USART1 initialization
// Communication Parameters: 8 Data, 1 Stop, No Parity
// USART1 Receiver: On
// USART1 Transmitter: On
// USART1 Mode: Asynchronous
// USART1 Baud Rate: 9600
UCSR1A=0x00;
UCSR1B=0x18;
UCSR1C=0x06;
UBRR1H=0x00;
UBRR1L=0x19;




while (1)
      { 
      
         ChipSelectAd=0;
       delay_ms(1000);
	     SPI_MasterInit();
		 SPI_MasterTransmit(0xff);
		  ChipSelectAd=1;
		delay_ms(1000);
     

          ChipSelectAd=0;
         delay_ms(1000);
		SPI_MasterInit();
		SPI_MasterTransmit(0x00);
		   ChipSelectAd=1;
	 	delay_ms(1000);
      
      a=getchar1(); 
            
        if (a=='u')
         {
          PORTD.4=1;   
          putchar1('A');  
         }

      
      }
}

 

[Bluestar88]

My code is answered when I deleted Usart1 configuration...Does anybody know why?

 

[Bluestar88]

Why I couldn't have SPI inteface and Usart1 (by FT232r) together?

 

[KlausST]

Hi,

Why I couldn't have SPI inteface and Usart1 (by FT232r) together?

We used many times both interfaces at the same time. No problem.

--> It must be something with your hardware or your code.

Klaus

 

[Bluestar88]

Thanks for your reply,
My code is attached. Would you please to take a look on it?
Thanks so much...

#include <mega128a.h>
#include <delay.h>

// SPI functions
#include <spi.h>


#define CLK1 PORTE.3
#define CLK2 PORTE.4
#define CLK PORTE.7


#ifndef RXB8
#define RXB8 1
#endif

#ifndef TXB8
#define TXB8 0
#endif

#ifndef UPE
#define UPE 2
#endif

#ifndef DOR
#define DOR 3
#endif

#ifndef FE
#define FE 4
#endif

#ifndef UDRE
#define UDRE 5
#endif

#ifndef RXC
#define RXC 7
#endif

#define FRAMING_ERROR (1<<FE)
#define PARITY_ERROR (1<<UPE)
#define DATA_OVERRUN (1<<DOR)
#define DATA_REGISTER_EMPTY (1<<UDRE)
#define RX_COMPLETE (1<<RXC)

// Get a character from the USART1 Receiver
#pragma used+
char getchar1(void)
{
char status,data;
while (1)
      {
      while (((status=UCSR1A) & RX_COMPLETE)==0);
      data=UDR1;
      if ((status & (FRAMING_ERROR | PARITY_ERROR | DATA_OVERRUN))==0)
         return data;
      }
}
#pragma used-

// Write a character to the USART1 Transmitter
#pragma used+
void putchar1(char c)
{
while ((UCSR1A & DATA_REGISTER_EMPTY)==0);
UDR1=c;
}
#pragma used-




// Declare your global variables here

void main(void)
{

unsigned char a;
// Port B initialization
// Func7=In Func6=In Func5=In Func4=In Func3=In Func2=Out Func1=Out Func0=Out 
// State7=T State6=T State5=T State4=T State3=T State2=0 State1=0 State0=0 
PORTB=0x00;
DDRB=0x07;          



// Port D initialization
// Func7=In Func6=In Func5=In Func4=In Func3=In Func2=In Func1=In Func0=In 
// State7=T State6=T State5=T State4=T State3=T State2=T State1=T State0=T 
PORTD=0x00;
DDRD=0x30;



PORTE=0x00;
DDRE=0xF8;           



// USART1 initialization
// Communication Parameters: 8 Data, 1 Stop, No Parity
// USART1 Receiver: On
// USART1 Transmitter: On
// USART1 Mode: Asynchronous
// USART1 Baud Rate: 9600
UCSR1A=0x00;
UCSR1B=0x18;
UCSR1C=0x06;
UBRR1H=0x00;
UBRR1L=0x19;


// SPI initialization
// SPI Type: Master
// SPI Clock Rate: 31.250 kHz
// SPI Clock Phase: Cycle Start
// SPI Clock Polarity: Low
// SPI Data Order: MSB First
SPCR=0x51;
SPSR=0x00;

while (1)
      {
      PORTB.0=0 ;             
      spi(0x00); 
      delay_ms(1);
      spi(0x1E);
      PORTB.0=1 ;
      
       PORTB.0=0 ;               //Mux bit
     // spi(0xBB);     
      spi(0x10); 
      delay_ms(1);
      spi(0x08);
      PORTB.0=1 ;
      
       PORTB.0=0 ;             
      spi(0x21); 
      delay_ms(1);
      spi(0x07);
      PORTB.0=1 ; 
     
      PORTB.0=0 ;            
      spi(0x00); 
      delay_ms(1);
      spi(0x1F);
      PORTB.0=1 ;       
      
        CLK2=0;
        CLK=1;
        delay_us(5 );
        CLK=0;
        delay_us(2 );
        CLK2=1;
        delay_us(3 );
        CLK=1;       
        delay_us(1 );       
        CLK2=0;
        delay_us(2 );
        CLK=0;  
        
        
         a=getchar1(); 
            
         if (a=='u')
         {
          PORTD.4=1;   
          putchar1('A');  
         }
        
         
      }
}

- - - Updated - - -

 

[bianchi77]

I use uart and SPI at once...
code for uart :

void usart_init( unsigned int ubrr )
{
	/* Set baud rate */

	UBRR0H = (unsigned char)(ubrr>>8);
	UBRR0L = (unsigned char)ubrr;
	/* Enable receiver and transmitter */
	UCSR0B = (1<<RXEN)|(1<<TXEN);
	/* Set frame format: 8data, 2stop bit */
	UCSR0C = (1<<USBS)|(3<<UCSZ0);
}
For SPI :

//8MHz SPI start
        SPCR = (1<<SPE)|(1<<MSTR);
        SPSR |= (1<<SPI2X); //8MHz

 

[Bluestar88]

Thanks,
My code is similar to yours, But I don't know why it doesn't answer....If I should do any special job in this case?

 

[bianchi77]

Reduce SPI to a slower speed ?

 

[Bluestar88]

I reduced SPI speed and tested it...then I increased the SPI speed....But the SCK pin is 1 always....It doesn't show any pulse.....

- - - Updated - - -

I found a point. It has a problem with getchar1 command. When I remove "a=getchar1();" from my code I have pulses on SCK pin.
Anybody knows why?

 

[KlausST]

Hi,

The only thing I can imagine is, that this function acts like a busy wait. Maybe it waits for a character to receive at the UART.
Then no other function can be processed.

Klaus

 

[Bluestar88]

I found getchar1() acts as polling it means it waits for data and it doesn't generate sck pulses...What Can I do to solve this problem?
I really need ti use getchar1() command for receive data in micro by USB?

 

[bianchi77]

do polling for few seconds, if there's no character accepted...exit polling ( loop ) and do SPI after SPI finish, back to polling again ?

 

[KlausST]

Hi,

with async data receive, I´d go for a interrupt solution.

Easy to implement, high reliability, low processing power, easy to access data with software fifo.

I know, the first time it seems to be difficult. But there should be plenty of code examples..

Klaus

 

[Bluestar88]

Would you please to take an example.... By applying rx interrupt, I use below code.....Please help me about details....

// USART1 Receiver interrupt service routine
interrupt [USART1_RXC] void usart1_rx_isr(void)
{
char status,data;
status=UCSR1A;
data=UDR1;
if ((status & (FRAMING_ERROR | PARITY_ERROR | DATA_OVERRUN))==0)
   {
   rx_buffer1[rx_wr_index1++]=data;
#if RX_BUFFER_SIZE1 == 256
   // special case for receiver buffer size=256
   if (++rx_counter1 == 0)
      {
#else
   if (rx_wr_index1 == RX_BUFFER_SIZE1) rx_wr_index1=0;
   if (++rx_counter1 == RX_BUFFER_SIZE1)
      {
      rx_counter1=0;
#endif
      rx_buffer_overflow1=1;
      }
   }
}

 

[KlausST]

Hi,

in main loop i´d just check if "rx_wr_index1 > 0)
Then you know if you received data. Now you should do an atomic [copy of buffer to a variable in main loop; and clearing the index] to further process the data.

The squared brackets mean that all within the brackes should be atomic.

Klaus

 

[Bluestar88]

Thanx

Would you please to give an example?
I really appreciate you...

 

[Bluestar88]

Nobody can help me?
I want to receive data by Interrupt SPI from computer...

 

[KlausST]

Hi,

Since this is not unusual, I'd Google for "interrupt driven SPI AVR".

Klaus