Hi Ken,

I tried it out today in my lab using the source code you provided, though
there is still no output but i can step though the program from from the
program memory using the MPLAB.

I wonder is it my hardware connection is wrong.
This is my connection:
Pin 1 - output of DAC
Pin 2, 5, 6 - Ground
Pin 3 - SCL (2k pullup resistor)
Pin 4 - SDA (2k pullup resistor)
Pin 7 - 5V
Pin 8 - No connection

I still couldn't get any voltage at the Pin 1. What could be the problem?
This is the source code after I implement.
I will try again tomorrow.

#include<p18f452.h>
#include<i2c.h>

//function prototype
void MAX517(unsigned char data_DAC, unsigned char I2C_Address);

void main(void){

 char data_DAC;
 char I2C_Address;

 //init condition
 TRISC = 0X1A; //Set SDA & SCL as 1. Activate I2C port

 OpenI2C(MASTER, SLEW_ON); //Initialize I2C module
 SSPADD = 9;     //400KHz Baud clock (9) @16MHz

 while(1){ //Start condition

   data_DAC = 0xFF;
   MAX517(data_DAC, I2C_Address);     //Write data to I2C DAC
   }//end of while

}//end of main

void MAX517( unsigned char data_DAC, unsigned char I2C_Address )
 {
      I2C_Address &= 0x58;   // Coerce address byte to WRITE mode

      StartI2C();            // Start condition

      WriteI2C(I2C_Address); // Address byte of DAC

      WriteI2C(0x00);        // Command byte

      WriteI2C(data_DAC);    // Output Data

      StopI2C();             // Stop condition
 }


----- Original Message -----
From: "Ken Pergola" <no_spam@LOCALNET.COM>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Thursday, March 18, 2004 4:03 AM
Subject: Re: [PIC]:I2C DAC test


> Hi Nicholas,
>
> Now wonder you are having problems -- see what happens when you provide
> extra details?
>
> When I first looked at your code, I thought it was written by you. I
thought
> your reference to the function 'AckI2C()' was a check for slave
acknowledge,
> but now that I know you are using the C18 compiler, the 'AckI2C()' is a
> function that generates a MASTER ACK which is what you do not want. It
looks
> like the WriteI2C() function automatically checks for a slave ACK.
>
>
> Therefore, try this (remove all 'AckI2C()' from your DAC code):
> I changed the int you were using to unsigned char, and made some other
> changes.
>
>
>
>  void MAX517( unsigned char DataByte,
>               unsigned char I2C_Address )
>  {
>       I2C_Address &= 0xFE;   // Coerce address byte to WRITE mode
>
>       StartI2C();            // Start condition
>
>       WriteI2C(I2C_Address); // Address byte of DAC
>
>       WriteI2C(0x00);        // Command byte
>
>       WriteI2C(DataByte);    // Output Data
>
>       StopI2C();             // Stop condition
>  }
>
>
> Let us know if this works. You might also want to process the function
> return code of the WriteI2C() function, but for now just try to get the
DAC
> working.
>
> Also, I would recommend a stiffer voltage reference versus the resistive
> voltage divider Vref that you are currently using.
> If you need help selecting a voltage reference just come on back with some
> questions. If you are breadboarding, you can easily find them in a TO-93
> package.
>
> Best regards,
>
> Ken Pergola
>
> --
> http://www.piclist.com hint: PICList Posts must start with ONE topic:
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>

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