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Benjamin,
Please supply additional details on the level shifter you are using.  It is possible for I2C to get stuck if the level shifters are not implemented correctly.  This happens when the slave device is transmitting a low and fails to receive the correct number of SCL edges.

A similar problem can occur with asynchronous battery backup switchovers.  Basically, if the RTC goes into backup mode while driving the I2C bus low it prevents the bus from returning to normal once main power is restored.  The action to correct this is listed below:
1. Drive the bus with START condition
2. Hi-Z the Master SDA output
3. Generate 9 SCL periods
4. Enable the Master SDA output
5. Drive the bus with a STOP condition
 
Do you know if the microcontroller is driving a NACK after the last data read byte?  The last data read byte should be followed by a NACK and a STOP.
 
 
Regards,
Brad

Thank you so much! The problem was the ACK I send instead of a NACK! However on the datasheet (figure 5, page 9) it says that a ACK must be send before a STOP and not a NACK. It is normal or it is a mistake? If it's a mistake, it should be corrected to avoid problems like mine. Thank you again for your help!

Best regards,

Benjamin

Benjamin,

Glad to help.  I have submitted a request for the data sheet to be updated.

Regards,

Brad

Hi Benjamin,

I am writing code in C for BQ32000, but not able to establish contact with BQ32000,

If possible will you help me with code you written for BQ32000.

I am using LM3S9B96 with internal I2C with pullup of 4.7k Ohm.

My code is for PIC µcontrollers and for the HI-TECH C Compiler but I think that it could help you. There is the header code :

#ifndef BQ32000_H_
#define BQ32000_H_

#define XTAL_FREQ 32MHZ

#include "i2c/i2c.h"
#include "delay.h"
#include "lcd.h"
#include <stdio.h>
#include <string.h>

//adresses
#define BQ_ADRW     0b11010000
#define BQ_ADRR     0b11010001

//Registres
#define SEC_REG     0
#define MIN_REG     1
#define HOURS_REG     2
#define DAY_REG     3
#define DATE_REG     4
#define MONTH_REG     5
#define YEAR_REG     6
#define CAL_REG     7
#define TCH2_REG     8
#define CFG2         9

//Jours de la semaine (DAY_REG)
#define DIMANCHE     1
#define LUNDI         2
#define MARDI         3
#define MERCREDI     4
#define JEUDI        5
#define VENDREDI     6
#define SAMEDI         7

void BQInit();
char getReg(char reg);
void setReg(char reg, char data);

void setSeconds(char);
void setMinutes(char);
void setHours(char);
void setDay(char);
void setDate(char);
void setMonth(char);
void setYear(char);

void getSeconds(char*);
void getMinutes(char*);
void getHours(char*);
void getDay(char*);
void getDate(char*);
void getMonth(char*);
void getYear(char*);

int dayToInt(char* day);
void intToDay(int d, char* jour);


#endif /*BQ32000_H_*/

and here the source code, if there is any problem, ask me

#include "BQ32000.h"

void BQInit() {
   
    OpenI2C(MASTER, SLEW_ON);
    SSPADD=19;  //clock = FOSC/(4 * (SSPADD + 1))
    setSeconds(128);
    setSeconds(0);
    setMinutes(0);
    setHours(12);
    setDay(LUNDI);
    setDate(1);
    setMonth(1); 
    setYear(10);
}

char getReg(char reg) {
    char data;
       
        IdleI2C();
    StartI2C();
        IdleI2C();
    WriteI2C(BQ_ADRW);
        IdleI2C();
    WriteI2C(reg);
        IdleI2C();
    StartI2C();
        IdleI2C();
    WriteI2C(BQ_ADRR);
    data=ReadI2C();
        NotAckI2C();
        IdleI2C();
    StopI2C();
   
    DelayUs(60); //temps minimum avant de re gŽrŽrer un Start

    return data;
}

void setReg(char reg, char data) {
   
        IdleI2C();
    StartI2C();
        IdleI2C();
    WriteI2C(BQ_ADRW);
        IdleI2C();
    WriteI2C(reg);       
        IdleI2C();
    WriteI2C(data);
        IdleI2C();   
    StopI2C();
   
    DelayUs(60); //temps minimum avant de re gŽrŽrer un Start
   
}

void getSeconds(char* sec) {
    char data = getReg(SEC_REG);
    *sec = (((data&112)>>4)*10+(data&15));
}

void getMinutes(char* min) {
    char data = getReg(MIN_REG);
    *min = (((data&112)>>4)*10+(data&15));
}

void getHours(char* hours) {
    char data = getReg(HOURS_REG);
    *hours = (((data&48)>>4)*10+(data&15));
}

void getDay(char* jour) {
    switch(getReg(DAY_REG) & 0x07) {
        case LUNDI:
            sprintf(jour ,"%s" ,"Lun");
        break;
        case MARDI:
            sprintf(jour ,"%s" ,"Mar");
        break;
        case MERCREDI:
            sprintf(jour ,"%s" ,"Mer");
        break;
        case JEUDI:
            sprintf(jour ,"%s" ,"Jeu");
        break;
        case VENDREDI:
            sprintf(jour ,"%s" ,"Ven");
        break;
        case SAMEDI:
            sprintf(jour ,"%s" ,"Sam");
        break;
        case DIMANCHE:
            sprintf(jour ,"%s" ,"Dim");
        break;
    }
}

void getDate(char* date) {
    char data = getReg(DATE_REG);
    *date = (((data&48)>>4)*10+(data&15));
}

void getMonth(char* month) {
    char data = getReg(MONTH_REG);
    *month = (((data&16)>>4)*10+(data&15));
}

void getYear(char* year) {
    char data = getReg(YEAR_REG);
    *year = (((data&240)>>4)*10+(data&15));
}

void setSeconds(char sec) {
    char data;
    getSeconds(&data);
    data &= 0x80;
    sec = ((sec/10)<<4)+sec-((sec/10)*10);
    setReg(SEC_REG, sec|data);
}

void setMinutes(char min) {
    char data;
    getMinutes(&data);
    data &= 0x80;
    min = ((min/10)<<4)+min-((min/10)*10);
    setReg(MIN_REG, min|data);
}

void setHours(char hours) {
    char data;
    getHours(&data);
    data &= 0xC0;
    hours = ((hours/10)<<4)+hours-((hours/10)*10);
    setReg(HOURS_REG, hours|data);
}

void setDay(char day) {
    setReg(DAY_REG, day);
}

void setDate(char date) {
    date = ((date/10)<<4)+date-((date/10)*10);
    setReg(DATE_REG, date);
}

void setMonth(char month) {
    month = ((month/10)<<4)+month-((month/10)*10);
    setReg(MONTH_REG, month);
}

void setYear(char year) {
    year = ((year/10)<<4)+year-((year/10)*10);
    setReg(YEAR_REG, year);
}

int dayToInt(char* day) {
    if(!strcmp(day,"Dim")) return 1;
    else if(!strcmp(day,"Lun")) return 2;
    else if(!strcmp(day,"Mar")) return 3;
    else if(!strcmp(day,"Mer")) return 4;
    else if(!strcmp(day,"Jeu")) return 5;
    else if(!strcmp(day,"Ven")) return 6;
    else if(!strcmp(day,"Sam")) return 7;
    return -1;
}

void intToDay(int d, char* jour) {
    switch(d) {
            case LUNDI:
                sprintf(jour ,"%s" ,"Lun");
            break;
            case MARDI:
                sprintf(jour ,"%s" ,"Mar");
            break;
            case MERCREDI:
                sprintf(jour ,"%s" ,"Mer");
            break;
            case JEUDI:
                sprintf(jour ,"%s" ,"Jeu");
            break;
            case VENDREDI:
                sprintf(jour ,"%s" ,"Ven");
            break;
            case SAMEDI:
                sprintf(jour ,"%s" ,"Sam");
            break;
            case DIMANCHE:
                sprintf(jour ,"%s" ,"Dim");
            break;
        }
}

Hi Benjamin

Thank you very much.

I apply code your, writing and reading to resisters is fine, but RTC is not updating time.

It contunusly shows value which is set by program not gating update.

Plz help if possible.

Hi Benjamin

Will you please give some more information about steps below.

data=ReadI2C();
        NotAckI2C();

Just before these instructions, I ask to the BQ32000 to give me the value of a register so I store this value into "data" and then I send a Not Acknowledge to confirm to the BQ3200 that I have receive the information correctly

Hi Benjamin,

BQ32000 is giving BCD output. Can I directly store in "char" or have to do some process?

Please help.

That's why I wrote the getSeconds, getMinutes, etc functions. They return the value of the register in a decimal number, not in BCD. If you want to convert them into strings you can use the sprintf function like this :

char h,m,s,aString[12];       // char type does not mean that you store characters into it, only that the data is on one byte (value≤255)

getHours(&h);

getMinutes(&m);

getSeconds(&s);

sprintf(aString,"%2dh %2dm %2ds",h,m,s); // aString will contain something like "08h 36m 54s"

note : Only the getDay function gives you a string directly

Hi Bejamin,

Thank you for great help,

My code is working now.

Thank you again......

you're welcome

hi Benjamin,

Where have you got that  header file of i2c, could you please put it up here on the forum,

it would be of great help to me.

Thanks

Varun

PS: because the one that I have is for firmware controlled master mode.

I've got all the I2C relative files from my compiler (Hi-Tech PICC18). I put you all of them in a zip file in attachment

5140.I2C.zip

Thank you Benjamin,

Varun