A few questions on DAC's and Shiftout

i'm using dac , arduino's shift out, i'm having few issues. here's dac: http://search.digikey.com/scripts/dksearch/dksus.dll?detail&name=ltc1446cn8%23pbf-nd

as far can tell it's working because getting voltage out of it. however, can't seem delay work because voltage constant , not delaying. here script:

code: [select]

int clockpin = 8;
int datapin = 9;
int latchpin = 10;
int data = 250;

void setup ()
     {
           pinmode (clockpin, output);
           pinmode (datapin, output);
           pinmode (latchpin, output);
     }

void loop ()
     {
           digitalwrite (latchpin, low);
           shiftout(datapin, clockpin, msbfirst, data);
           digitalwrite (latchpin, high);
           delay (1000);
     }

i know code partially working because when change value data variable changes voltage. also, loosely based on shiftout tutorial here. work better?:

code: [select]

int clockpin = 8;
int datapin = 9;
int latchpin = 10;
int data = 250;

void setup ()
     {
           pinmode (clockpin, output);
           pinmode (datapin, output);
           pinmode (latchpin, output);
               digitalwrite (latchpin, low);
     }

void loop ()
     {
           shiftout(datapin, clockpin, msbfirst, data);
           digitalwrite (latchpin, high);
               digitalwrite (latchpin, low);
           delay (1000);
     }

i'm thinking first script didn't let latch pin go low before delay, still high throughout delay. can't test yet (hard @ work...ya know?), later. thought i'd other eyes looking @ before tested theroy.  

im not sure want do, im assuming there shiftregister in there somewhere? delay() dont affect in way, shiftregisters output last set to, , constant.

maybe more trying?

code: [select]

int clockpin = 8;
int datapin = 9;
int latchpin = 10;
int data = 250;

void setup ()
     {
           pinmode (clockpin, output);
           pinmode (datapin, output);
           pinmode (latchpin, output);
     }

void loop ()
     {
           digitalwrite (latchpin, low);
           shiftout(datapin, clockpin, msbfirst, data);
           digitalwrite (latchpin, high);
           delay (1000);
           digitalwrite (latchpin, low);
           shiftout(datapin, clockpin, msbfirst, 0x00);
           digitalwrite (latchpin, high);
           delay (1000);
     }


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