Hi Ken,

There is still not output from the DAC. I am suspecting that I may initial
the TRISC incorrectly. What do you think might be the problem?
I have tied the Vref (pin8) to high, just wanna see whether is ther any
voltage in the output.
I have double check my hardware connection and it seem alright. Please
advise me?

Thanks,
Nicholas

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

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

void main(void){
    char data_DAC;
    char DAC_Address = 0x58;

    //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 = 0x7F;
        MAX517(data_DAC, DAC_Address);     //Write data to I2C DAC
        }//end of while
    }//end of main

//DAC function
void MAX517(unsigned char data_DAC, unsigned char DAC_Address)
{
    DAC_Address = (DAC_Address & 0xFE);     // Coerce address byte to WRITE
mode
    StartI2C();     // Start condition
    WriteI2C(DAC_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: Friday, March 19, 2004 1:19 AM
Subject: Re: [PIC]:I2C DAC test


> Nicholas wrote:
>
>
> Sorry for not explaining that.
>
> By adding the 'I2C_Address' parameter to your MAX517 function, I made it
> more universal versus the way you coded it. Your code was not bad at all,
> I'm just showing you a different perspective, that's all.
>
> In other words, you had hard-coded the I2C address so that only a MAX517
> with a slave device address of 0x2C would work.
> By having your MAX517 function accept an 'I2C_Address' argument, I'm
showing
> you how you can accommodate up to 4 MAX517 devices on the I2C bus with one
> function if you ever need future expansion.
>
> Be careful Nicholas, you did not use my exact example that I posted
> yesterday. Somehow you changed my code. You need to add my original code
> back in.
>
> My original reference was:
>
>      I2C_Address &= 0xFE;   // Coerce address byte to WRITE mode
>
>
> The reference to 'I2C_Address &= 0xFE;' should have been written more
> clearly as:
>
>   I2C_Address = ( I2C_Address & 0xFE );
>
> Both do the same thing -- just short-hand versus long-hand.
>
> The '&' is the bitwise AND operator. What this is doing is forcing your
R/W
> bit (bit 0) of your I2C address to be 0 without affecting the other 7
bits.
> In this case, it is just defensive programming since you could have passed
> in 0x59 (R/W bit = 1 = read) (correct 7-bit device address but incorrect
> 8-bit I2C address).
>
> Nicholas, I think you are doing great so far -- keep up the good work and
do
> not give up. You'll be posting soon sharing your success with us.
>
>
> Best regards,
>
> Ken Pergola
>
> P.S. Don't forget to make that change: I2C_Address = ( I2C_Address &
0xFE );
>
> --
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