twi.h File Reference

---

Detailed Description

TWI driver library.

This file contains basic drivers for the AVR32 TWI, with support for all master modes, TWI settings and clock speeds.

• Compiler: IAR EWAAVR32 and GNU GCC for AVR32
• Supported devices: All AVR32 devices with a TWI module can be used.
• AppNote: AVR32107 - Using TWI as a master on the AVR32

Author:

Atmel Corporation: http://www.atmel.com
Support email: avr32@atmel.com

$Name$

Revision

$RCSfile$

Date

Definition in file twi.h.

This graph shows which files directly or indirectly include this file:

Go to the source code of this file.

Data Structures
struct	twi_options_t
struct	twi_package_t
Defines
#define	TWI_ARBITRATION_LOST   -2
#define	TWI_INVALID_ARGUMENT   -1
#define	TWI_NO_CHIP_FOUND   -3
#define	TWI_RECEIVE_NACK   -5
#define	TWI_RECEIVE_OVERRUN   -4
#define	TWI_SEND_NACK   -7
#define	TWI_SEND_OVERRUN   -6
#define	TWI_SUCCESS   0
#define	TWI_TIMEOUT   5000
Functions
int	twi_init (struct twi_options_t *opt)
int	twi_probe (char chip_addr)
int	twi_read (struct twi_package_t *package)
int	twi_write (struct twi_package_t *package)

---

Define Documentation

#define TWI_ARBITRATION_LOST   -2

Definition at line 73 of file twi.h.

#define TWI_INVALID_ARGUMENT   -1

Definition at line 72 of file twi.h.

Referenced by twi_read(), and twi_write().

#define TWI_NO_CHIP_FOUND   -3

Definition at line 75 of file twi.h.

Referenced by twi_probe().

#define TWI_RECEIVE_NACK   -5

Definition at line 77 of file twi.h.

Referenced by twi_read(), and twi_write().

#define TWI_RECEIVE_OVERRUN   -4

Definition at line 76 of file twi.h.

#define TWI_SEND_NACK   -7

Definition at line 80 of file twi.h.

Referenced by twi_write().

#define TWI_SEND_OVERRUN   -6

Definition at line 79 of file twi.h.

#define TWI_SUCCESS   0

Definition at line 71 of file twi.h.

Referenced by main(), twi_probe(), and twi_set_speed().

#define TWI_TIMEOUT   5000

Definition at line 82 of file twi.h.

Referenced by twi_probe(), twi_read(), and twi_write().

---

Function Documentation

int twi_init

(

struct twi_options_t *

opt

)

twi_init: - Initialize the twi module

Parameters:

*opt

Options for initializing the twi module (see twi_options_t)

Definition at line 88 of file twi.c.

References twi_options_t::cpu_hz, twi_options_t::speed, twi_options_t::twi_addr, and twi_set_speed().

{

        volatile avr32_twi_t *twi = &AVR32_TWI;

        /* Reset, enable master transfer and disable slave transfer */
        twi->cr = // (1<<AVR32_TWI_CR_SWRST_OFFSET) |
                        (1<<AVR32_TWI_CR_MSEN_OFFSET);
        twi->iadr = opt->twi_addr;

        return twi_set_speed(opt->speed, opt->cpu_hz);

}

Here is the call graph for this function:

int twi_probe

(

char

chip_addr

)

twi_probe: - Test if a chip answers for a given twi address

Parameters:

chip_addr,:

address of the chip which is searched for

Returns:

: 0 if a chip was found, -1 otherwhise

Definition at line 102 of file twi.c.

References TWI_NO_CHIP_FOUND, TWI_SUCCESS, and TWI_TIMEOUT.

{
        volatile avr32_twi_t *twi = &AVR32_TWI;
        int timeout = TWI_TIMEOUT;

        twi->mmr = (chip_addr << 16) | (1<<AVR32_TWI_MMR_MREAD_OFFSET);
        twi->iadr = 0;
        twi->cr = (1<<AVR32_TWI_CR_START_OFFSET) | (1<<AVR32_TWI_CR_STOP_OFFSET);

        do {
                if ((twi->sr) & (1<<AVR32_TWI_SR_RXRDY_OFFSET))
                {
                        return TWI_SUCCESS;
                }
        } while (!(twi->sr & (1<<AVR32_TWI_SR_TXCOMP_OFFSET)) && --timeout);

        return TWI_NO_CHIP_FOUND;
}

int twi_read

(

struct twi_package_t *

package

)

twi_read: - Read multiple bytes from a another twi compatible device

Parameters:

package

Package information and data (see twi_package_t)

Returns:

0 in case of success

Definition at line 121 of file twi.c.

References twi_package_t::addr, twi_package_t::addr_length, twi_package_t::buffer, twi_package_t::chip, twi_package_t::length, TWI_INVALID_ARGUMENT, TWI_RECEIVE_NACK, and TWI_TIMEOUT.

{
        volatile avr32_twi_t *twi = &AVR32_TWI;
        unsigned int i = 0;
        unsigned int timeout = TWI_TIMEOUT;

        if (package->length == 0)
        {
                return TWI_INVALID_ARGUMENT;
        }

        /* clear buffer for data */
        for (i = 0; i< package->length; i++)
                package->buffer[i] = '_';
        i=0;

        twi->mmr = (package->chip << AVR32_TWI_MMR_DADR_OFFSET) |
                        ((package->addr_length &3) << 8) |
                        (1<<AVR32_TWI_MMR_MREAD_OFFSET);
        twi->iadr = package->addr;

        /* send start condition */
        twi->cr = (1<<AVR32_TWI_CR_START_OFFSET);


        /* get data */
        while (i < package->length){
          if (twi->sr & (1<<AVR32_TWI_SR_RXRDY_OFFSET)){
            package->buffer[i++] = twi->rhr; /*put the byte in the receive holding register */  
            //print(usart, "got one byte\n");
          }

          /* Wait for ACK */
          while (!(twi->sr & (1<<AVR32_TWI_SR_RXRDY_OFFSET)) && (--timeout));

          /* Check for timeout */
          if(timeout==0){
            return TWI_RECEIVE_NACK;    
          }

          timeout=TWI_TIMEOUT; /* reset timer */
        } /* end while loop */

        /* send stop condition */
        twi->cr |= (1<<AVR32_TWI_CR_STOP_OFFSET);

        /* add terminating char */
        package->buffer[i++] = '\0';

        if (twi->sr & (1<<AVR32_TWI_SR_NACK_OFFSET))
                return TWI_RECEIVE_NACK;

        if (i < package->length)
                return TWI_INVALID_ARGUMENT;
        return i;
}

int twi_write

(

struct twi_package_t *

package

)

Definition at line 179 of file twi.c.

References twi_package_t::addr, twi_package_t::addr_length, twi_package_t::buffer, twi_package_t::chip, twi_package_t::length, TWI_INVALID_ARGUMENT, TWI_RECEIVE_NACK, TWI_SEND_NACK, and TWI_TIMEOUT.

{
        volatile avr32_twi_t *twi = &AVR32_TWI;
        int i = 0;
        int timeout = TWI_TIMEOUT;

        /* No data to send */
        if (package->length == 0)
        {
                return TWI_INVALID_ARGUMENT;
        }

        twi->cr |= (0<<AVR32_TWI_CR_MSDIS_OFFSET);

        /* set slave address and 3 internal address byte length */
        twi->mmr = (0<<AVR32_TWI_MMR_MREAD_OFFSET) | \
                        (package->chip << AVR32_TWI_MMR_DADR_OFFSET) | \
                        ((package->addr_length & 3) << 8);
        /* set internal address for remote chip */
        twi->iadr = package->addr;

        /* set start condition */
        twi->cr |= (1<<AVR32_TWI_CR_START_OFFSET);

        /* send data*/
        while (i < package->length){

                if (twi->sr & (1<<AVR32_TWI_SR_TXRDY_OFFSET))
                        twi->thr = package->buffer[i++]; /*put the byte in the transmit holding register */

                /* Wait for ACK */
                while (!(twi->sr & (1<<AVR32_TWI_SR_TXCOMP_OFFSET)) && timeout--);

                if(timeout==0)
                        return TWI_RECEIVE_NACK;

                timeout=TWI_TIMEOUT; /* reset timer */

        }


        /* set stop condition */
        twi->cr |= (1<<AVR32_TWI_CR_STOP_OFFSET);

        /* NACK */
        if (twi->sr & (1<<AVR32_TWI_SR_NACK_OFFSET))
                return TWI_SEND_NACK;

        /* not all bytes were sent */
        if (i < package->length)
        {
                /* TIMEOUT */
                return TWI_INVALID_ARGUMENT;
        }

        /* Everything went ok */

        return i;
}

---