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No ACK from Slave (I2C communication PIC16f1459 & LM75)

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adda

Joined: 12 Oct 2015
Posts: 1

No ACK from Slave (I2C communication PIC16f1459 & LM75)

Posted: Mon Oct 12, 2015 9:37 am

I am unable to receive an ACK from the slave. I send the initial address with write bit, but do not get an acknowledgement.
--main.c

Code:

#include <xc.h>
#include <stdlib.h>
#include "I2C.h"
#define CDC_DATA_OUT_EP_SIZE 64
#define CDC_DATA_IN_EP_SIZE 64
#define _XTAL_FREQ 32000000
unsigned char Byte1;
unsigned char Byte2;
unsigned int Int1;
unsigned char readBuffer[CDC_DATA_IN_EP_SIZE];

void main(void)
{

while(1)
{

I2CInit();
// __delay_ms(5);
I2CStart();
// __delay_ms(5);

//I2CWait();

I2CSend(0x48|0x27);
I2CAck();
I2CSend(0x00);
I2CAck();
I2CRestart();
I2CSend(0x49|0x27);
I2CAck();
Byte1 = I2CRead();
I2CNak();
I2CStop();
}

}

I2C lib

Code:

/** INCLUDES *******************************************************/
#include <xc.h>
#include <stdlib.h>
#include <stdint.h>
#include <string.h>
#include <stddef.h>
#include "I2C.h"

#define BUFF_SIZE 64
#define SDA TRISBbits.TRISB4 // I2C bus
#define SCL TRISBbits.TRISB6 //
#define SCL_IN PORTBbits.RB6 //
#define SDA_IN PORTBbits.RB4 //
#define CDC_DATA_OUT_EP_SIZE 64
#define CDC_DATA_IN_EP_SIZE 64

/** VARIABLES ******************************************************/
typedef struct buffer{
float buff[BUFF_SIZE];
int readIndex;
int writeIndex;
}buffer;

static char buttonMessage[] = "Button pressed.\r\n";
static char buttonMessage2[] = "Button pressed2.\r\n";
static uint8_t readBuffer[CDC_DATA_OUT_EP_SIZE];
static uint8_t writeBuffer[CDC_DATA_IN_EP_SIZE];
unsigned char readBuffer1[CDC_DATA_IN_EP_SIZE];
unsigned char Byte1;
unsigned char Byte2;
unsigned int Int1;
float float1;

/*I2C Implementation*/
void I2CInit(void)
{
SDA = 1;
SCL = 1;
SDA_IN = 0;
SCL_IN = 0;

SSPADDbits.SSPADD = 0x8;
SSPSTAT = 0xA8;//0b10101000; //No slew rate
SSPADD = 0x27;
SSPCON1bits.SSPM = 0x08;
SSPCON1 = 0x28;
SSPSTATbits.SMP = 1;
SSPSTATbits.CKE = 0;
//Disable SMBus inputs
// SSPADD = 0x27; //100 KHz
// SSPCON1 = 0b00101000; //I2C Master mode
SSPCON3 = 0x00; //Rien de slave

}

/*
Function: I2CStart
Return:
Arguments:
Description: Send a start condition on I2C Bus
*/
void I2CStart()
{

SSPCON2bits.SEN = 1; /* Start condition enabled */
//while(SSPCON2bits.SEN); /* automatically cleared by hardware */
//LATCbits.LATC0 = 1; /* wait for start condition to finish */
}

/*
Function: I2CStop
Return:
Arguments:
Description: Send a stop condition on I2C Bus
*/
void I2CStop()
{
SSPCON2bits.PEN = 1; /* Stop condition enabled */
//while(SSPCON2bits.PEN); /* Wait for stop condition to finish */
LATCbits.LATC0 = 1; /* PEN automatically cleared by hardware */
}

/*
Function: I2CRestart
Return:
Arguments:
Description: Sends a repeated start condition on I2C Bus
*/
void I2CRestart()
{
SSPCON2bits.RSEN = 1; /* Repeated start enabled */
//while(SSPCON2bits.RSEN); /* wait for condition to finish */
}

/*
Function: I2CAck
Return:
Arguments:
Description: Generates acknowledge for a transfer
*/
void I2CAck()
{

SSPCON2bits.ACKDT = 0; /* Acknowledge data bit, 0 = ACK */
SSPCON2bits.ACKEN = 1; /* Ack data enabled */
//while(SSPCON2bits.ACKEN); /* wait for ack data to send on bus */
}

/*
Function: I2CNck
Return:
Arguments:
Description: Generates Not-acknowledge for a transfer
*/
void I2CNak()
{
SSPCON2bits.ACKDT = 1; /* Acknowledge data bit, 1 = NAK */
SSPCON2bits.ACKEN = 1; /* Ack data enabled */
//while(SSPCON2bits.ACKEN); /* wait for ack data to send on bus */
}

/*
Function: I2CWait
Return:
Arguments:
Description: wait for transfer to finish
*/
void I2CWait()
{
while ((SSPCON2 == 0x1F ) || ( SSPSTAT == 0x04 ) );
/* wait for any pending transfer */
}

/*
Function: I2CSend
Return:
Arguments: dat - 8-bit data to be sent on bus
data can be either address/data byte
Description: Send 8-bit data on I2C bus
*/
void I2CSend(unsigned char dat)
{

SSPBUF = dat; /* Move data to SSPBUF */
//while(BF); /* wait till complete data is sent from buffer */
I2CWait(); /* wait for any pending transfer */
}

/*
Function: I2CRead
Return: 8-bit data read from I2C bus
Arguments:
Description: read 8-bit data from I2C bus
*/
unsigned char I2CRead(void)
{
unsigned char temp;
/* Reception works if transfer is initiated in read mode */
SSPCON2bits.RCEN = 1; /* Enable data reception */
//while(!SSPSTATbits.BF); /* wait for buffer full */
temp = SSPBUF; /* Read serial buffer and store in temp register */
I2CWait(); /* wait to check any pending transfer */
return temp; /* Return the read data from bus */
}

/*end implementation functions*/

PCM programmer

Joined: 06 Sep 2003
Posts: 21708

Posted: Mon Oct 12, 2015 9:47 am

Quote:

#include <xc.h>

This is XC8 code. You're on the wrong forum. Every PIC C compiler
has its own forum. Try these two forums:
Microchip XC8 forum:
http://www.microchip.com/forums/f249.aspx
Microchip i2c forum:
http://www.microchip.com/forums/f10.aspx

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