1 bit shifting to right on 3-wire serial communication. why?

regall · Joined: 15 Jan 2005 Posts: 6 Location: Turkey

what is the reason of shifting 1 bit to the right on 3-wire serial communication?

#fuses HS,NOWDT
#use delay (clock=8000000)
#use RS232(BAUD=9600, XMIT=PIN_C6, RCV=PIN_C7, STREAM=COM1)

data=fgetc(COM1);
spi_write(data);
spi_read();
delay_ms(10);
data1=spi_read(0);
data1=data1<<1; //solving the problem like that
printf("The Response=%x\n\r",data1);

TSchultz · Joined: 08 Sep 2003 Posts: 66 Location: Toronto, Canada

I suspect you may be using the wrong signaling with your SPI. You can setup the SPI for any of the 4 modes. Using the wrong mode can cause a problem like this. Also it looks like you are shifting left.

What is the device you are communication to with SPI?
How have you setup the SPI?

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