How to connect ports via loopback using the XMOS simulator

• version

  1.1.1

• scope

  Example.

  This code is provided as example code for a user to base their code on.

• description

  How to connect ports via loopback using the XMOS simulator

• boards

  Unless otherwise specified, this example runs on the SliceKIT Core Board, but can easily be run on any XMOS device by using a different XN file.

The xTIMEcomposer simulator contains a plugin mechanism that lets you model external components via plugins. As part of the xTIMEcomposer tools, a pre-built loopback plugin is provided which enables ports/pins to be connected, thus allowing testbenches to be written in XC.

For example, compile the following code for the XK-1A target:

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

port p1 = PORT_UART_RX;
port p2 = PORT_UART_TX;

int main() {

  par {
    {
       p1 <: 1;
    }
    {
       p2 when pinseq(1) :> void;
       printstrln("Done!\n");
    }
  }
  return 0;
}

The intention is to connect the pins of port p1 to the pins of port p2, thus allowing the example to complete successfully. Note: If you run the above code without making the connection, the execution will pause indefinitely, due to the fact that p2 will never go high.

There are a number of ways to specify the ports/pins to connect using the loopback plugin.

Using the port name as defined in the XN file

xsim --plugin LoopbackPort.dll "-port PORT_UART_RX 1 0 -port PORT_UART_TX 1 0" a.xe

Using the port names as defined by the XS1 architecture

xsim --plugin LoopbackPort.dll "-port tile[0] XS1_PORT_1I 1 0 -port tile[0] XS1_PORT_1J 1 0" a.xe

Specifying the pins directly

xsim --plugin LoopbackPort.dll "-pin 0 X0D24 -pin 0 X0D25" a.xe