RTOS/AM5726: Using system clock for time measurement

Hi Carlo,

You can use the Timestamp module for time measurements.  You can add the following line to your .cfg file:

var Timestamp = xdc.useModule('xdc.runtime.Timestamp');

Since you are building for the A15 on, BIOS will select the ti.sysbios.family.arm.a15.TimestampProvider as the Timestamp delegate.  The A15 TimestampProvider uses the A15's internal PMC counter, which is running at the CPU frequency.

In your C code, to measure time:

#include <xdc/runtime/Timestamp.h>

UInt32 t1, t2, delta;

t1 = Timestamp_get32();

...

t2 = Timestamp_get32();

delta = t2 - t1;  // Number of CPU cycles taken

Is that the sort of time measurement you were looking for?

Best regards,

Janet

Hi Carlo,

You can use Timestamp_getFreq() to determine the frequency of the timestamp counter:

  #include <xdc/runtime/Timestamp.h>
  #include <xdc/runtime/Types.h>

    Void Timestamp_getFreq(Types_FreqHz *freq)

Check the XDC tools cdoc for more information (see the xdctools release notes on documentation).  Here is an example:

    Types_FreqHz freq;

    Timestamp_getFreq(&freq);
    t1 = Timestamp_get32();
    ...
    t2 = Timestamp_get32();
    msecs = ((t2 - t1) * 1000) / freq.lo;    // Time in milliseconds

Best regards,

Janet

Hi Carlo,

The Timestamp frequency returns the value that BIOS thinks the CPU is running at (1500 MHz).  If your CPU is running at a lower speed (1000 MHz), you can add these lines to your .cfg file:

var BIOS = xdc.useModule('ti.sysbios.BIOS');

BIOS.cpuFreq.lo = 1000000000;

Setting BIOS.cpuFreq does not actually change the CPU frequency.  It is only informational so that timestamps and Clock ticks are accurate.

Best regards,

Janet