TC 1321

[rodolfo]

Somebody has used the TC1321?

I bought 50 pcs for a redesign and have tried to use it with standard I2C PCM functions.
It does not work.

I have considered the discussion posted: Fri Dec 05, 2003 7:36 am "10 bit DAC I2C"

Program listing:

#include <16f873.h>
#fuses HS,NOWDT,NOPROTECT
#device PIC16f873 *=16
#use delay(clock=20000000) //20 MHz
#use i2c(MASTER,SCL=PIN_C3,SDA=PIN_C4,NOFORCE_SW) //HW forced


void outda(long val)
{
int v1=0;
int v2=0;

val&=0x03FF;
val<<=6;
v1=(byte)val; //LSB
v2=val>>8; //MSB
i2c_start();
i2c_write(0x90); //address
i2c_write(0x00); //command
i2c_write(v2); //data
i2c_write(v1); //data
i2c_stop();

}


main()
{
long aux;
while(True)
{
delay_ms(20);
for(aux=220;aux<1024;aux++)
{
delay_ms(3);
outda(aux);
}
}
} //END


Compiler:

CCS PCM C Compiler, Version 2.713

Circuit:

uC: PIC 16F874-20/sp
DAC: TC1321
Pull up resistors: 22k tied to 5VDC.

Can somebody tell me if successfully have used the TC1321?

Thanks in advance.

[Kenny]

Pullup resistors should be in the range 2k2 to 4k7.
Add NOLVP to #fuses line.
Comments by PCM Programmer in the old post apply - you need a reference voltage and a buffer amp.
It's an old compiler version, the NOFORCE_SW for hardware i2c has been replaced with FORCE_HW in later versions, a bit confusing really.
If you still have problems, try software i2c by leaving out NOFORCE and add these two lines to set the pins to inputs - the pullups will pull both SCL and SDA to the idle high state.
output_float(PIN_C3);
output_float(PIN_C4);

HTH