TWI Atmega8 nie mogę odczytać danych z HMC5883l

Męczę się z tym problemem już od bardzo długiego czasu, więc postanowiłem wreszcie poszukać pomocy na forum. Mianowicie nie potrafię w żaden sposób sprawić by ten układ wysłał mi jakiekolwiek dane. Połączenie atmegi z kompasem jest poprawne ponieważ skaner wyszukuje jego adres:

Robiąc to bardziej ręcznie funkcjami z biblioteki też działa:

Problem zaczyna się gdy chce coś odczytać z jakiegoś rejestru:

Program zawiesza się czekając na dane, mimo że według dokumentacji powinien odczytać 0x20.

Nie wiem co mogę zrobić, projekt bez tego stoi w miejscu. Program napisałem najbardziej prosty jak się da. Nie mam analizatora żeby sprawdzić co się dzieje na liniach ale pewnie niczego nowego by to nie wniosło. Na dole podaje kod biblioteki, ale wątpie że jest to jej wina ponieważ obsługiwała wcześniej RTC bez problemu. Błagam o pomoc bo już nie mam na to dziadostwo siły.

/*************************************************************************
* Title: I2C master library using hardware TWI interface
* Author: Peter Fleury <pfleury@gmx.ch> http://jump.to/fleury
* File: $Id: twimaster.c,v 1.4 2015/01/17 12:16:05 peter Exp $
* Software: AVR-GCC 3.4.3 / avr-libc 1.2.3
* Target: any AVR device with hardware TWI 
* Usage: API compatible with I2C Software Library i2cmaster.h
**************************************************************************/
#include <inttypes.h>
#include <compat/twi.h>
#include "i2cmaster.h"

/* define CPU frequency in hz here if not defined in Makefile */
#ifndef F_CPU
#define F_CPU 16000000UL
#endif

/* I2C clock in Hz */
#define SCL_CLOCK 100000L


/*************************************************************************
Initialization of the I2C bus interface. Need to be called only once
*************************************************************************/
void i2c_init(void)
{
/* initialize TWI clock: 100 kHz clock, TWPS = 0 => prescaler = 1 */

TWSR = 0; /* no prescaler */
TWBR = ((F_CPU/SCL_CLOCK)-16)/2; /* must be > 10 for stable operation */

}/* i2c_init */


/*************************************************************************	
Issues a start condition and sends address and transfer direction.
return 0 = device accessible, 1= failed to access device
*************************************************************************/
unsigned char i2c(void)
{
/* send stop condition */
TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWSTO);

// wait until stop condition is executed and bus released
while(TWCR & (1<<TWSTO));

}/* i2c_stop */


/*************************************************************************
Send one byte to I2C device

Input: byte to be transfered
Return: 0 write successful 
1 write failed
*************************************************************************/
unsigned char i2c_write( unsigned char data )
{	
uint8_t twst;

// send data to the previously addressed device
TWDR = data;
TWCR = (1<<TWINT) | (1<<TWEN);

// wait until transmission completed
while(!(TWCR & (1<<TWINT)));

// check value of TWI Status Register. Mask prescaler bits
twst = TW_STATUS & 0xF8;
if( twst != TW_MT_DATA_ACK) return 1;
return 0;

}/* i2c_write */


/*************************************************************************
Read one byte from the I2C device, request more data from device 

Return: byte read from I2C device
*************************************************************************/
unsigned char i2c_readAck(void)
{
TWCR = (1<<TWINT) | (1<<TWEN) | (1<<TWEA);
while(!(TWCR & (1<<TWINT))); 

return TWDR;

}/* i2c_readAck */


/*************************************************************************
Read one byte from the I2C device, read is followed by a stop condition 

Return: byte read from I2C device
*************************************************************************/
unsigned char i2c_readNak(void)
{
TWCR = (1<<TWINT) | (1<<TWEN);
while(!(TWCR & (1<<TWINT)));

return TWDR;

}/* i2c_readNak */[/syntax]
[syntax=c]#ifndef _I2CMASTER_H
#define _I2CMASTER_H
/************************************************************************* 
* Title: C include file for the I2C master interface 
* (i2cmaster.S or twimaster.c)
* Author: Peter Fleury <pfleury@gmx.ch>
* File: $Id: i2cmaster.h,v 1.12 2015/09/16 09:27:58 peter Exp $
* Software: AVR-GCC 4.x
* Target: any AVR device
* Usage: see Doxygen manual
**************************************************************************/

/**
@file
@defgroup pfleury_ic2master I2C Master library
@code #include <i2cmaster.h> @endcode

@brief I2C (TWI) Master Software Library

Basic routines for communicating with I2C slave devices. This single master 
implementation is limited to one bus master on the I2C bus. 

This I2c library is implemented as a compact assembler software implementation of the I2C protocol 
which runs on any AVR (i2cmaster.S) and as a TWI hardware interface for all AVR with built-in TWI hardware (twimaster.c).
Since the API for these two implementations is exactly the same, an application can be linked either against the
software I2C implementation or the hardware I2C implementation.

Use 4.7k pull-up resistor on the SDA and SCL pin.

Adapt the SCL and SDA port and pin definitions and eventually the delay routine in the module 
i2cmaster.S to your target when using the software I2C implementation ! 

Adjust the CPU clock frequence F_CPU in twimaster.c or in the Makfile when using the TWI hardware implementaion.

@note 
The module i2cmaster.S is based on the Atmel Application Note AVR300, corrected and adapted 
to GNU assembler and AVR-GCC C call interface.
Replaced the incorrect quarter period delays found in AVR300 with 
half period delays. 

@author Peter Fleury pfleury@gmx.ch http://tinyurl.com/peterfleury
@copyright (C) 2015 Peter Fleury, GNU General Public License Version 3

@par API Usage Example
The following code shows typical usage of this library, see example test_i2cmaster.c

@code

#include <i2cmaster.h>


#define Dev24C02 0xA2 // device address of EEPROM 24C02, see datasheet

int main(void)
{
unsigned char ret;

i2c_init(); // initialize I2C library

// write 0x75 to EEPROM address 5 (Byte Write) 
i2c(); // set stop conditon = release bus


// read previously written value back from EEPROM address 5 
i2c();

for(;;);
}
@endcode

*/


/**@{*/

#if (__GNUC__ * 100 + __GNUC_MINOR__) < 304
#error "This library requires AVR-GCC 3.4 or later, update to newer AVR-GCC compiler !"
#endif

#include <avr/io.h>

/** defines the data direction (reading from I2C device) in i2c(void);


/** 
@brief Issues a start condition and sends address and transfer direction 

@param addr address and transfer direction of I2C device
@retval 0 device accessible 
@retval 1 failed to access device 
*/
extern unsigned char i2c_start(unsigned char addr);


/**
@brief Issues a repeated start condition and sends address and transfer direction 

@param addr address and transfer direction of I2C device
@retval 0 device accessible
@retval 1 failed to access device
*/
extern unsigned char i2c_rep_start(unsigned char addr);


/**
@brief Issues a start condition and sends address and transfer direction 

If device is busy, use ack polling to wait until device ready 
@param addr address and transfer direction of I2C device
@return none
*/
extern void i2c_start_wait(unsigned char addr);


/**
@brief Send one byte to I2C device
@param data byte to be transfered
@retval 0 write successful
@retval 1 write failed
*/
extern unsigned char i2c_write(unsigned char data);


/**
@brief read one byte from the I2C device, request more data from device 
@return byte read from I2C device
*/
extern unsigned char i2c_readAck(void);

/**
@brief read one byte from the I2C device, read is followed by a stop condition 
@return byte read from I2C device
*/
extern unsigned char i2c_readNak(void);

/** 
@brief read one byte from the I2C device

Implemented as a macro, which calls either @ref i2c_readAck or @ref i2c_readNak

@param ack 1 send ack, request more data from device<br>
0 send nak, read is followed by a stop condition 
@return byte read from I2C device
*/
extern unsigned char i2c_read(unsigned char ack);
#define i2c_read(ack) (ack) ? i2c_readAck() : i2c_readNak(); 



/**@}*/
#endif

__________

Komentarz dodany przez: Treker

No ale przecież biblioteka marudzi, że nie udała się już pierwsza operacja I2C. Funkcja i2c_start() oddaje 0 gdy wszystko poszło OK, a 1 gdy status jest niefajny. Moim zdaniem używasz złego adresu slave'a. Nie wiem co to za skaner tam masz, ale HMC5883 ma 0x3C/3D.