How to achieve maximum spi communication speed?

[Einly]

Dear all,

I am interfacing AD7716 with PIC16f876. It is a 4 channel adc. Every channel will give 32 bits output. To complete reading the digital output, we have to shift in 32x4 bits using spi communication.

Below is a part of my code:

#use fast_io(b)

//For each channel, I only shift_left 2 bytes since I am only interested in the 2 most significant bytes. After that I just provide 16 clock pulses, without actually reading the data.

for(int i=0;i<16;i++)
{
output_high(SCLK);
output_low(SCLK);
sheft_left(chan0,2,input(SDATA));
}

for(int i=0;i<16;i++)
{
output_high(SCLK);
output_low(SCLK);
}

for(int i=0;i<16;i++)
{
output_high(SCLK);
output_low(SCLK);
sheft_left(chan1,2,input(SDATA));
}

for(int i=0;i<16;i++)
{
output_high(SCLK);
output_low(SCLK);
}

for(int i=0;i<16;i++)
{
output_high(SCLK);
output_low(SCLK);
sheft_left(chan2,2,input(SDATA));
}

for(int i=0;i<16;i++)
{
output_high(SCLK);
output_low(SCLK);
}

for(int i=0;i<16;i++)
{
output_high(SCLK);
output_low(SCLK);
sheft_left(chan3,2,input(SDATA));
}

for(int i=0;i<16;i++)
{
output_high(SCLK);
output_low(SCLK);
}

#use standard_io(b);

I check with oscilloscope and found out that to shift in all the 4 channels, I need around 340us, means 85 us for each channel.

May I know how can I shorten the time needed to shift all the data? By
1) Using different code?
2) Using hardware spi?
3) Using different PIC microcontroller chip?
4) Using DSP?
_________________
Einly

[Neutone]

Change syntax to count down. This;