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SPI: �It�s possible send 16 CLK�s on a SPI instruction?

 
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carm
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SPI: �It�s possible send 16 CLK�s on a SPI instruction?
PostPosted: Tue Jan 31, 2006 9:32 am     Reply with quote

I have a problem.
I have an ADC wich need 16 bit instructions (LTC1859).
If i use SPI instructions, i only can send 8 bits with CLK�s, and if i repeat the instruction with the correct code, appear a "dead time" between clk�s.
�It�s possible make 2 byte intructions with SPI without the "dead time"?

Here is the code:


#include <16F873A.h>
#device adc=10
#device ICD=TRUE
#include <stdio.h>
#fuses XT,NOWDT,PUT,NOPROTECT,NOBROWNOUT,NOLVP
#use delay(clock=4000000)
#use rs232(baud=9600,xmit=pin_c6,rcv=pin_c7)



long conv=0,convh,convl;


void main (void){

setup_adc(adc_off);
setup_adc_ports(no_analogs); //configuro puerto A como digital

set_tris_a(0xFF);
set_tris_b(0xFF);
set_tris_c(0x92); //configuro puertos

setup_spi(spi_master|spi_l_to_h|spi_clk_div_4); //configuro modo SPI

output_low(pin_c2); //inicializo RD nivel bajo
output_low(pin_c0); //inicializo CONVST a nivel bajo



while(TRUE){

spi_write(0x84); //configuration to AD
spi_write(0x00); //send 0x00
output_high(pin_c0);

while (!input(pin_c1)){}
conv=spi_read(0); //
output_low(pin_c0);

printf("\n\r%ld",conv);
}//cierro while


}//cierro main
libor



Joined: 14 Dec 2004
Posts: 288
Location: Hungary

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PostPosted: Tue Jan 31, 2006 11:06 am     Reply with quote

In synchronous data transfers (those with a CLK line) like SPI, there must be no problem having a 'dead time' anywhere in the data stream, that is the reason the CLK line is implemented for.
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