#include <avr/io.h>

#include "config.h"

#include "i2csw.h"

// This Library uses slow (100kHz) Bus timing

inline void delay_5u(){

asm volatile(

"delay_5u_lp%=:\n\t"

"dec %0 \n\t"

"brne delay_5u_lp%=\n\t"

::"r" ((uint8_t)((5ul*F_CPU)/(3ul*1000000ul))) );

}

inline void delay_2u5(){

asm volatile(

"delay_2u5_lp%=:\n\t"

"dec %0 \n\t"

"brne delay_2u5_lp%= \n\t"

::"r" ((uint8_t)((2.5*F_CPU)/(3ul*1000000ul))) );

}

#define QDEL() delay_2u5()

#define HDEL() delay_5u()

//Control I2C bus with DDR register to simulate open collector behavior

#define SDA_LO() SDADDR |= (1<<SDA)

#define SDA_HI() SDADDR &= ~(1<<SDA)

#define SCL_LO() SCLDDR |= (1<<SCL)

#define SCL_HI() SCLDDR &= ~(1<<SCL)

// defines and constants

#define READ 0x01 // I2C READ bit

//generate a start or repeated start condition

void i2cStart(){

QDEL();

SDA_HI();

HDEL();

SCL_HI();

HDEL();

SDA_LO();

HDEL();

SCL_LO();

}

void i2cStop(){

HDEL();

SCL_HI();

HDEL();

SDA_HI();

}

uint8_t i2cPutbyte(uint8_t b)

{

uint8_t i, ack;

for (i=0;i<8;i++){

QDEL();

if ( b & 0x80 ){

SDA_HI();

}else{

SDA_LO();

}

QDEL();

SCL_HI(); //clock out bit

HDEL();

SCL_LO();

b <<= 1;

}

QDEL();

SDA_HI(); //release SDA to be able to get ack

QDEL();

SCL_HI(); //clock in ack

QDEL();

ack = SDAPIN & (1<<SDA); // get the ACK bit

QDEL();

SCL_LO();

QDEL();

SDA_LO(); //leave with SDA low

return (ack == 0); // return ACK value

}

uint8_t i2cGetbyte(uint8_t ack)

{

uint8_t i, b = 0;

QDEL();

SDA_HI();

for(i=0;i<8;i++){

HDEL();

b <<= 1;

SCL_HI(); //clock in bit

HDEL();

if(SDAPIN & (1<<SDA)) b |= 1;//read bit

SCL_LO();

}

QDEL();

//only ack if requested

if (ack){

SDA_LO();

}

QDEL();

SCL_HI();

HDEL();

SCL_LO();

return b; // return received byte

}

//this is a dummy for now

void i2cInit(void)

{

}

//write to i2c eeprom in multibyte write mode

int8_t i2cEeWrite( uint16_t address, uint8_t *data, uint16_t len )

{

uint8_t ack;

union{uint8_t b[2]; uint16_t w;} addr;

addr.w = (uint16_t)address;

while(len){

i2cStart();

//set start address

#ifdef EEPROM_2_ADDR_BYTES

if (! i2cPutbyte(EEPROM_ADDRESS)) goto error;

if (! i2cPutbyte(addr.b[1])) goto error;

if (! i2cPutbyte(addr.b[0])) goto error;

#else

if (! i2cPutbyte(EEPROM_ADDRESS|(addr.b[1]<<1))) goto error;

if (! i2cPutbyte(addr.b[0])) goto error;

#endif

do{

len--;

if(! i2cPutbyte(*data++) ) goto error;

addr.w++;

//keep writing until a 4 byte boundary in eeprom is reached

}while(len && (addr.b[0] % EEPROM_SECTOR_SIZE));

//initiate and wait for internal write cycle

do{

i2cStop();

i2cStart();

ack = i2cPutbyte(EEPROM_ADDRESS);

}while(!ack);

i2cPutbyte(0);

i2cStop();

}

return 0;

error:

i2cStop();

return -1;

}

//read bytes from eeprom to buffer

void i2cEeRead(uint8_t *data, uint16_t address, uint16_t len)

{

uint8_t ack;

union{uint8_t b[2]; uint16_t w;} addr;

addr.w = (uint16_t)address;

while(len){

i2cStart();

#ifdef EEPROM_2_ADDR_BYTES

//setup address

i2cPutbyte(EEPROM_ADDRESS);

i2cPutbyte(addr.b[1]);

i2cPutbyte(addr.b[0]);

//do a repeated start condition

i2cStart();

i2cPutbyte(EEPROM_ADDRESS | READ );

#else

//setup address

i2cPutbyte(EEPROM_ADDRESS | (addr.b[1]<<1) );

i2cPutbyte(addr.b[0]);

//do a repeated start condition

i2cStart();

i2cPutbyte(EEPROM_ADDRESS | READ | (addr.b[1]<<1) );

#endif

do{

//keep on going until all bytes are sent, or the end of a field is reached

//ack = (len != 1) && (addr.b[0] != 0xff) && (addr.b[0] != 0x7f)&& (addr.b[0] != 0x3f )&& (addr.b[0] != 0xcf);

ack = 0;

*data++ = i2cGetbyte(ack);//send no ack on last byte

addr.w++;

len--;

}while (ack);

i2cStop();

}

}

#ifdef EE_DETECT

//Probes if a device with this address acks

uint8_t i2cProbe(uint8_t addr){

uint8_t ack;

i2cStart();

ack = i2cPutbyte(addr);

i2cStop();

return ack;

}

//detect if there is a valid i2c eeprom card inserted

//returns card size in sectors of 256 bytes

//a return value of zero means no valid card

uint8_t i2cEeDetect(){

uint8_t retval;

HDEL();

if( !(SDAPIN & (1<<SDA)) ){

//SDA is low, so this can't be an i2c card

return 0;

}

if(i2cProbe(0x23)){

//device 0x23 shouldn't be present, so this is not a valid card

return 0;

}

//find out size of card by probing sub addresses - max 2kiB

for(retval=0;retval<8;retval++){

if( ! i2cProbe(0xa0|(retval<<1)) )

break;

}

if(i2cProbe(0x67)){

//device 0x67 shouldn't be present, so this is not a valid card

return 0;

}

//seems to be a valid card, so we return the size

return retval;

}

#endif