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beginning the spi, please help

 
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krakatau



Joined: 19 Feb 2009
Posts: 9

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beginning the spi, please help
PostPosted: Thu Feb 19, 2009 9:59 am     Reply with quote
I'm new in ccs, but i need to spi communication. I tried this code.

for master
Code:

void main()
{

   setup_adc_ports(NO_ANALOGS);
   setup_adc(ADC_OFF);
   setup_spi(SPI_MASTER | SPI_L_TO_H);
 
   setup_timer_1(T1_DISABLED);
   setup_timer_2(T2_DISABLED,0,1);

   // TODO: USER CODE!!
while(1)
 {
   output_low(pin_a5);
   spi_write(0XAA);
   delay_ms(1);
   output_high(pin_a5);
 }
}



for slave
Code:

int x;
void main()
{
setup_adc_ports(NO_ANALOGS);
setup_adc(ADC_OFF);
setup_spi(SPI_SLAVE);

setup_timer_1(T1_DISABLED);
setup_timer_2(T2_DISABLED,0,1);

// TODO: USER CODE!!
delay_ms(100);

while(1)
 {
   x=spi_read();
   delay_ms(1);
   output_b(x);
 }

}

the above code is operating
but i want send two byte sequential (master to slave).
so i want see on leds.1 second 0xAA one second 0x55.
Code:

void main()
{

   setup_adc_ports(NO_ANALOGS);
   setup_adc(ADC_OFF);
   setup_spi(SPI_MASTER | SPI_L_TO_H);
 
   setup_timer_1(T1_DISABLED);
   setup_timer_2(T2_DISABLED,0,1);

   // TODO: USER CODE!!
while(1)
{
output_low(pin_a5);
spi_write(0XAA);
delay_ms(1);
output_high(pin_a5);

delay_ms(1000);

output_low(pin_a5);
spi_write(0x55);
delay_ms(1);
output_high(pin_a5);

}
}

the above code
i can see 0xAA but i can't 0x55 in outputs
what can i do?


thanks
ECACE



Joined: 24 Jul 2006
Posts: 94

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PostPosted: Thu Feb 19, 2009 12:54 pm     Reply with quote
From your code:

Code:
while(1)
{
output_low(pin_a5);
spi_write(0XAA);
delay_ms(1);
output_high(pin_a5);

delay_ms(1000);

output_low(pin_a5);
spi_write(0x55);
delay_ms(1);
output_high(pin_a5);

}
}



You pass AA out to the slave, wait 1 sec, pass 55 out to the slave, then imediately send AA again.
Your slave is probably displaying it, but it is happening so fast that you can't see it.
You need to add a delay_ms(1000) after your 0x55 transmition. You will probably see it then.

So you should have:

Code:
while(1)
{
output_low(pin_a5);
spi_write(0XAA);
delay_ms(1);
output_high(pin_a5);

delay_ms(1000);

output_low(pin_a5);
spi_write(0x55);
delay_ms(1);
output_high(pin_a5);

delay_ms(1000);                  // Add this delay line to your code

}

}
_________________
A HW Engineer 'trying' to do SW !!! Run!!!
krakatau



Joined: 19 Feb 2009
Posts: 9

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PostPosted: Fri Feb 20, 2009 1:25 am     Reply with quote
Yes, I've done.
I don't believe that and I didn't see delay_ms. Exactly as you say. I tried very much on yesterday but I couldn't. But this morning I saw your message. I tried. It was done.
Thank you very much ECACE.

The following code is executing.
for master:
Code:

void main()
{

   setup_adc_ports(NO_ANALOGS);
   setup_adc(ADC_OFF);
   setup_spi(SPI_MASTER | SPI_L_TO_H);
 
   setup_timer_1(T1_DISABLED);
   setup_timer_2(T2_DISABLED,0,1);

   // TODO: USER CODE!!
while(1)
{
output_low(pin_a5);
spi_write(0XAA);
delay_ms(1);
output_high(pin_a5);

delay_ms(1000);

output_low(pin_a5);
spi_write(0x55);
delay_ms(1);
output_high(pin_a5);

delay_ms(1000);
}
}


For slave:
Code:

int x;
void main()
{

   setup_adc_ports(NO_ANALOGS);
   setup_adc(ADC_OFF);
   setup_spi(SPI_SLAVE);
 
   setup_timer_1(T1_DISABLED);
   setup_timer_2(T2_DISABLED,0,1);

   // TODO: USER CODE!!
delay_ms(100);
while(1)
{
x=spi_read();
delay_ms(1);
output_b(x);

}
}
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