AVR Freaks

Thanks a lot, it is executing but it says nothing other than 0x00. Just  a basic doubt, How is MISO working here. I understand that its pin value is 0,hence its input. So, I read value only from the SPDR? Is there no connections of MISO here?

Hello,
I tried it..but nothing's changed. I have attached the sensor datasheet. Kindly look at it.

I am sorry that I did not mention it .I changed to volatile. It is able to evaluate but it says only zero. I want to read my wriiten value. If you just look at  pg.64, there is a flow chart for communication test,i just tried it. BTW ofcourse I changed the OPCODES accordingly. Pg 40.,there is a simple I2C test, I am trying exactly the same with same opcodes on SPI interface.

0x90  -writing

0x47 -address

0xFF -data

and so on..

EDIT:flowchart pg:74

#define F_CPU 1000000UL
#include <avr/io.h>
#include <util/delay.h>
#include <avr/interrupt.h>
#include "spi_master.h"

volatile char result ;
void spi_master_int (void)
{

	DDRB = 0x07 ;  //PB2=MOSI ,PB1=SCK as output ,PB0 =SS as output
	SPCR = SPCR = (1<<SPE) | (1<<MSTR) | (1<<CPHA) ; //spi enabled master mode, spi_mode 1,prescalar :fosc/16

 }

int main(void)
{
    spi_master_int();

   while (1)
    {
		//spi_send(0x7E);
		spi_send(0xA1);
		spi_send(0x47);
		spi_send(0xBA);
		spi_send(0x21);
		spi_send(0x47);
		result = spi_send(0xFF);

    }
}

my spi.h file:

void spi_master_int (void);
uint8_t spi_send (uint8_t r_data);

uint8_t spi_send (uint8_t r_data)
{

	SPDR = r_data;
	while(!(SPSR & (0x80) ))
	{};
	return (SPDR);
}

These are the modified codes. And what is the difference between CS and SS ? is both not the same?

DDRB = 0x07

According to the data sheet , if i set the directon pin as 1,it is output, that is my PORT B's last pin is SS.

PB0= 1 // SS

PB1=1  // SCK and so on.

 

If you have connected the SS from the uC to the sensor SSN, there is no control of the SS signal in the above code.

Yes the controller is connected to the SS of the slave. What should I do to control/select it?

I am very sorry that I have attached a different datasheet . My apologies. But the pins and config was all same.I just noted it when clawson told me the pg number. I am really sorry

http://www.atmel.com/Images/Atme...

This is my datasheet.

In this Pg:365,the SS pin can be configured as  input or I really I dont understand how should I control it ? As I did not use interrupt or used the SPIE register.

I feel bad for making such a trouble for the easiest interface. :(

NO NO ...Its between sensor (datasheet from post number: 15) and the AVR. The mistake is the datasheet of AVR was interchanged. This is trhe right one :

http://www.atmel.com/Images/Atme...

Thanks for the clarity. But My second value doesnot go into the bus at all. . . . I am not sure if this is a good/bad

question

 void spi_select()
{
	DDRB = 0x06;
}

void spi_deselect()
{

 DDRB = 0x07;
}

//inside main - this while loop after initialising

while (1)
    {
        spi_select();
        spi_send(0xA1);
        spi_send(0x47);

        spi_send(0xBA);

        spi_send(0x21);

        spi_send(0x47);

        result = spi_send(0xFF);
        spi_deselect();
    };

   

This is my updated code. I made a breakpoint at result. But the program is held at the never ending loop during the transfer of the second value.

In the following code,it is held at the while(!(SPSR));

uint8_t spi_send (uint8_t r_data)
{

	SPDR = r_data;
	while(!(SPSR & (0x80) ))
	{};
	return (SPDR);
}

how can this be cleared?

oops . It is while(!(SPSR &(1<<SPIF)));

According to the datasheet,

if any,

DDRBx = 0 : PinPBX= input

DDRBx=1; pinPBx=output

According to this post,

Set SS high when not doing SPI, set low just prior to SPI read/write, set high again after read/write completes for each SPI access

while initialising, I have made PB0 ,the only chipselect pin present , PB0 as 1;

in the function select () : it is made to PB0=0 (DDRB = 0x06)

in the function deselct (): it is made toPB0= 1 (DDRB = 0x07)

 void spi_select()
 {
	PORTB &=(~ 1<< PB0);
 }

 void spi_deselect()
 {

	 PORTB |=(~ 1<< PB0);
 }

Thank you all for the clear explanations and guidance. I will use this above code and let u know the results soon

Hello all,

I made the chnages with

void spi_select()
 {
	PORTB &= ~( 1<< PB0);
 }

 void spi_deselect()
 {

	 PORTB |= (1<< PB0);
 }

The values are sent and updated . But the result register always remains zero (post 33). What could be the problem ?

int main(void)
{
    spi_master_int();
	
	spi_select();
	
	spi_send(0x88); //turn on
	
	spi_deselect();	
		
	while (1)
	{	
		spi_select();
		spi_send(0x90); //wrte
		
		spi_send(0x47); //address
		
		spi_send(0xBA); //data
		
		spi_deselect();
		
		spi_select();
		spi_send(0x10); //read
		spi_send(0x47); //address
		result = spi_send(0xFF); //reading back data
		spi_deselect();
   };

This is my code . From pag 4-4 ,I am trying to do the same that is happening in i2c with SPI. I expected to get the data ' BA' to be read in the result register

Thanks a lot for your time and pointing out the points.So fine,it is clear . I think I will have to deal with the hardware first.  This is the program (that I have quoted )I have written. Let us assume, the chip is not damaged.

If the chip is normal,is my expectation of ' reading the  value (BA) in result register' right?

For now, I am not doing any measurements but just trying to do what is in pg 4-4 via SPI. Am I procedding the right way?

#define F_CPU 1000000UL
#include <avr/io.h>
#include <util/delay.h>
#include <avr/interrupt.h>
#include "spi_master.h"

volatile char result ;

void spi_select()
{
	PORTB &= ~ (1<< PORTB0);

}

void spi_deselect()
{
	PORTB |= (1<< PORTB0);

}
void spi_master_int (void)
{

	DDRB = 0x07 ;  //PB2=MOSI ,PB1=SCK as output ,PB0 =SS as output
	SPCR =  (1<<SPE) | (1<<MSTR) | (1<<CPHA) ; //spi enabled master mode, spi_mode 1,prescalar :fosc/16

 }

int main(void)
{
    spi_master_int();

	spi_select();

	spi_send(0x88);

	spi_deselect();	

	while (1)
	{
		spi_select();
		spi_send(0x90);

		spi_send(0x47);

		spi_send(0xBA);

		spi_deselect();

		spi_select();
		spi_send(0x10);
		spi_send(0x47);
		result = spi_send(0xFF);
		spi_deselect();
   };

}

//this spi_master.h

void spi_master_int (void);
uint8_t spi_send (uint8_t r_data);
void spi_select (void);
void spi_deselect(void);

uint8_t spi_send (uint8_t r_data)
{

	SPDR = r_data;
	while(!(SPSR & (1<<SPIF) ))
	{};
	return (SPDR);
}

This is my full present code. IIC_EN pin is connected to the ground. I am using the debugger,but I did not get any change in the value. As I added SPDR,result and r_data in the watch section. Each time the different datas are passed on it (each send invoked) and the r_data value changes,but no change in the SPDR and result. They are always 0x00.

EDIT : I want to make sure that there is no problem with the software /n programming part.

I was able to see the change in SPIF register  from 0x80 to 0x00.  But I cannot see change is the SPDR register.

The best way to "debug" something like SPI is with a DSO or Logic Analyzer.

Unfortunately I do not have a DSO.

To achieve this ,is my program and approach proper ?

EDIT:

And if the 'result 'in my program is optimised. Then how will I be able to read the results if I am starting to do the measurements. In Pg 75 and 76 there are steps about reading the results. It is writing the opcodes and then reading the value, which is almsot the same as I do here.