XCore Exchange

#include <xs1.h>
#include <stdio.h>
#include <print.h>

port temp = XS1_PORT_1A;

in buffered port:8 inP = XS1_PORT_1B;

clock clk25 = XS1_CLKBLK_1;

int x;

int main(void)
{
configure_clock_rate(clk25, 100, 4);
configure_in_port(inP, clk25);
start_clock(clk25);
par
{

{
temp <: 1;
temp <: 0;
temp <: 1;
temp <: 0;
temp <: 1;
temp <: 0;
temp <: 1;
temp <: 1;
}

{ for(int i=0 ; i<8 ; i++)

{ inP :> x; }
printf("%d",x);
}
}
return 0;
}

CousinItt wrote: ↑Mon Jun 24, 2019 1:00 pm It looks like you're assuming that the two tasks in your par statement will run in lock step. Since you have no clocking on the output, there's no guarantee as to what your input buffer will get.

Secondly, you're reading your input eight times in a loop. That's not necessary for a buffered input - the input statement will block until the buffer is full, and you only need to read it once.

Try using a buffered output port with the same clock as the receiver, and enabling the clock when both are set up. There's no need to do that in separate tasks.

Also, try using the simulator with waveform tracing.

It looks like you're assuming that the two tasks in your par statement will run in lock step. Since you have no clocking on the output, there's no guarantee as to what your input buffer will get.

Try using a buffered output port with the same clock as the receiver, and enabling the clock when both are set up. There's no need to do that in separate tasks.

CousinItt wrote: ↑Tue Jun 25, 2019 12:49 pm See what mon2 said.

The following code (based on AN10046 and AN10047) works, but out of sync by one bit. It's simpler if you have an external signal on which to synchronise.

See also 6.9 onwards in the XMOS Programming Guide, rev F, and XS1 Ports: use and specification for more information.

Code: Select all

#include <xs1.h>
#include <stdio.h>

in buffered port:8 in_port = XS1_PORT_1A;
out buffered port:8 out_port = XS1_PORT_1B;

clock clk = XS1_CLKBLK_1;

int main(void) {
  unsigned data;
  configure_clock_rate(clk, 100, 8);
  configure_out_port(out_port, clk, 0);
  configure_in_port(in_port, clk);

  out_port <: 0x43;
  start_clock(clk);

  in_port :> data;
  printf("received 0x%x\n", data);

  return 0;
}

CousinItt wrote: ↑Thu Jun 27, 2019 11:29 am I don't think this is simple for a looped-back buffered port without any additional synchronisation (which is easy to add). There are library functions that allow you to do adjust sampling edges and delays, but I doubt they would make a fundamental difference. You can also enable clock tracing in the simulator, which gives you more information about what's happening in the ports.