Problem with i2c code for lpc2138

[adamarul]

Hi All,
I am using lpc2138 as i2c master to read eight ADCs(AD7400) using a mux(PCA9548a).
After sending the slave address, i see only level high(NACK) in the SDA line instead of level 0(ACK).
Attached the code and simulator screenshot(image location: https://obrazki.elektroda.pl/3144481400_1406226026.png ) for your reference.the control remains in the statement "while(!(I2C1STAT == Status));" in the function "I2C_Send_Byte" as NACK is received(I2C1STAT = 0x20) instead of ACK(I2C1STAT = 0x18). Could you please suggest me if there any modification required.
Thanks in advance

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Code C - [expand]
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// Header:    I2C interface
// File Name: I2c_Interface
// Date:     
 
 
 /*
   Device address
----------------
 
 |----SLAVE Address -----------|
 
 |0 | 1 | 0 | 0 | A2 | A1 | A0 | R/W-bar |
 
 |-Fixed--------|--Programmable-|
 
*/
 
 
 
#include<lpc213x.h>
  /* Master */
#define START                   0x08
#define REP_START               0x10
 
/* Master Transmitter */
#define MT_SLA_ACK              0x18
#define MT_SLA_NACK             0x20
#define MT_DATA_ACK             0x28
#define MT_DATA_NACK            0x30
#define MT_ARB_LOST             0x38
 
/* Master Receiver */
#define MR_ARB_LOST             0x38
#define MR_SLA_ACK              0x40
#define MR_SLA_NACK             0x48
#define MR_DATA_ACK             0x50
#define MR_DATA_NACK            0x58
 
/* Slave Transmitter */
#define ST_SLA_ACK              0xA8
#define ST_ARB_LOST_SLA_ACK     0xB0
#define ST_DATA_ACK             0xB8
#define ST_DATA_NACK            0xC0
#define ST_LAST_DATA            0xC8
 
/* Slave Receiver */
#define SR_SLA_ACK              0x60
#define SR_ARB_LOST_SLA_ACK     0x68
#define SR_GCALL_ACK            0x70
#define SR_ARB_LOST_GCALL_ACK   0x78
#define SR_DATA_ACK             0x80
#define SR_DATA_NACK            0x88
#define SR_GCALL_DATA_ACK       0x90
#define SR_GCALL_DATA_NACK      0x98
#define SR_STOP                 0xA0
 
/* Misc */
#define NO_INFO                 0xF8
#define BUS_ERROR               0x00
 
// bit defines
#define I2CON_AA            2
#define I2CON_SI            3
#define I2CON_STO           4
#define I2CON_STA           5
#define I2CON_I2EN          6
 
// defines and constants
#define TWCR_CMD_MASK       0x0F
#define TWSR_STATUS_MASK    0xF8
 
// return values
#define I2C_OK              0x00
#define I2C_ERROR           0x01
 
 
 
typedef enum
{
    I2C_IDLE = 0, I2C_BUSY = 1,
    I2C_MASTER_TX = 2, I2C_MASTER_RX = 3,
    I2C_SLAVE_TX = 4, I2C_SLAVE_RX = 5
} eI2CStateType;
 
// functions
//u32 init_i2c(void) ;
// Initialize I2C (TWI) interface
char I2C_Init(char bitrateKHz);
// Deinitialize I2C (TWI) interface
char I2C_DeInit(void);
 
// Set the I2C transaction bitrate (in KHz)
char I2CSetBitrate(char bitrateKHz);
 
// Set an I2C start condition 
char I2C_Start_Condition(void);
// Set an I2C stop condition 
char  I2C_Stop_Condition(void);
 
char I2C_Send_Byte(char , char );
char I2C_Receive_Byte(void);
 
char I2C_Master_Write(char *,char * );
char I2C_Master_Read(char *);
 
char I2C_Slave_Write(char *);
char I2C_Slave_Read(char *);
 
 
 
char bitrate_KHz=100;
  char Send_Cmd[2]={0xA0,0x00};
   char Send_Data[2]={1,'a'};
 
 
 
void Delay_Ms(unsigned int i)  
{
    i*=2728; 
    while(i--); 
}    
     
char I2C_Init(char bitrateKHz)
{
    //PINSEL0 |= 0X00000050;
    
    PINSEL0 |= 0X30C00000;
    IODIR0 = 0x4800;
//  PCONP |= 0x80000;
    I2C1CONCLR |= 0X6c;
    I2C1CONSET = 0X40; 
    I2CSetBitrate(bitrateKHz);
    return 0;   
}
 
char I2CSetBitrate(char bitrateKHz)
{
    unsigned int b;
    b=(20000/(bitrateKHz *2));
    //I2C0SCLL = b;
    //I2C0SCLH = b;
    I2C1SCLL = 50; // PCLK = 10MHz, I2C Speed = 100KHz
    I2C1SCLH = 50;
    return 0;
}
 
 
char  I2C_Start_Condition(void)
{
    I2C1CONSET = 0X60;//enable start condition in master tx mode
    while(!((I2C1CONSET & 0x08)==0x08));//checking for SI to go high 
    while(!(I2C1STAT == START));
    I2C1CONCLR = 0x00000028;//clearing SI and START 
    return 0;
}
 
char I2C_Stop_Condition(void)
{
    I2C1CONSET = 0X50;              // sending stop bit by making STO high
    while(!((I2C1CONSET & 0x10)==0x10));
    I2C1CONCLR = 0X08;
    return 0;
}
 
 
char I2C_Send_Byte(char data, char Status)
{
    I2C1DAT = data;//slave address and W bit loaded
    //Delay_Ms(1000);
    while(!(I2C1STAT == Status));//waiting for slave addr to be send 
    I2C1CONCLR = 0x28;//clearing SI
    return 0;
}
char I2C_Receive_Byte(void)
{
    char Rec_Data;
    while(!(I2C1STAT == MR_DATA_ACK));
    Rec_Data=I2C1DAT;
    I2C1CONCLR = 0X28;//clearing SI*/
    return Rec_Data;    
}
 
 
/*
    buffer  - Send device address, memory addr, length and data 
*/
char I2C_Master_Write(char* buffer,char* buffer2)
{
    unsigned char length,dat1=0xE0,dat2=0x06;
    I2C1CONSET = 0X40; 
    if((I2C_Start_Condition())!=0)
    return 1;
    
 
    if((I2C_Send_Byte(dat1,MT_SLA_ACK))!=0)
        return 1;
    //Delay_Ms (1000000);
    if((I2C_Send_Byte(dat2,MT_DATA_ACK))!=0)
    return 1;  
/*  length=*buffer++;
    do{
    if((I2C_Send_Byte(*buffer2++,MT_DATA_ACK))!=0)
    return 1;
    }while(--length);  */
    if((I2C_Stop_Condition())!=0)
    return 1;
    return 0;
}
 
 
char I2C_Master_Read(char *buffer)
{
    char *dat,length,i,a[100];
    char dat1 = 0xE1, dat2 = 0x03;
    I2C1CONSET = 0X60;//enable start bit in Master mode
    if((I2C_Start_Condition())!=0)
    return 1;
    if((I2C_Send_Byte(dat1,MT_SLA_ACK))!=0)
    return 1;
    if((I2C_Send_Byte(dat2,MT_DATA_ACK))!=0)
    return 1;
    if((I2C_Stop_Condition())!=0)
    return 1;
/* 
    length=  *buffer--;
    buffer--;
 
    I2C1CONSET = 0X44;//enable start bit in Master mode      
 
    if((I2C_Start_Condition())!=0)
    return 1;       
    if((I2C_Send_Byte((*buffer |0x01),MR_SLA_ACK))!=0)               //(*buffer |0x01)
    return 1;   
    for(i=0;i<length;i++)
    {
        if((a[i] =I2C_Receive_Byte())==0)
        return 1;
    }
    a[i]='\0';
 
    if((I2C_Stop_Condition())!=0)
    return 1;
    dat=a;
//return dat;*/
 return 0;
 
}
/*******************************************************
        EEPROM Write 
        Send_CMD send Slave address,Memory loc (i.e) 0xA0,0x00
        Send_Dat send Length and data (i.e) 1,'a'
 
        
 
*******************************************************/
  int main()
  {
   char  Send_Cmd = 0xe1,send = 0x01 ;
   I2C_Init(bitrate_KHz);
   I2C_Master_Write(&Send_Cmd,&send);
   I2C_Master_Read (&Send_Cmd);
   while(1)
   {
 
   }
  }

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[adamarul]

Also, why is that the value set in the register I2CCONSET gets cleared during runtime., SI bit in particular ? Is this a hardware driven register ? that is., does this register value change based on any hardware event ?