help with shift_right and shift_left

[John Morley]

Hi All,

I'm trying to use the shift_right and shift_left functions to communicate with a serially connected (CLK and DATA) external sensor. I first need to shift out an 8 bit command to the sensor, and then shift in a byte that comprises the requested data. I don't seem to be able to compile these functions, and I'm not sure where I'm going wrong. Here is the code:

// This shifts 8 bits out on SDATA, LSB first each time SCLK goes high. Value to be shifted out is contained in Cmd.
int Cmd = 0x05;
int i;

for(i=0;i<8;++i)
{
output_bit(SDATA,shift_right(Cmd,1,0));
SCLK = 1; // Clock high
SCLK = 0; // Clock low
}

AND

// This shifts a byte in on SDATA, MSB first each time SCLK goes high.
int8 databyte;
output_float(SDATA); //release the data line
for(i=0; i<8; ++i)
{
SCLK = 1; // Clock to high
shift_left(databyte,2,input(SDATA));
SCLK = 0; // Clock to low
}

BTW, SDATA and SCLK are defined above using:

//-----< Port location defines >-----
#byte port_a = 0x05
#byte port_b = 0x06


//-----< Pin defines >-----

//Interface Bit Definitions
#bit SDATA = port_b.0 // Data
#bit SCLK = port_b.1 // Clock

The PIC is a 16F84.

Thanks,

John
___________________________
This message was ported from CCS's old forum
Original Post ID: 144515308

[john cutler]

for(i=0;i<8;++i)
:= {
:= output_bit(SDATA,shift_right(Cmd,1,0));
:= SCLK = 1; // Clock high
:= SCLK = 0; // Clock low
:= }


Look in compiler manual - I think you need:

output_bit(SDATA,shift_right(&Cmd,1,0));

Also don't you want the clock to make it's transtion before and after the shifting?

Hope this is helpful

Jc
___________________________
This message was ported from CCS's old forum
Original Post ID: 144515310