NXC ForceOff to turn off the NXT

[mattallen37]

Is the ForceOff command the best way to power off an NXT while tasks are running? I made a program execute at startup by naming it "! Startup", and I made the NXT shut off by pressing the exit button. I just want to be sure that ForceOff is the best way to do this.

[afanofosc]

I would use PowerDown() or SleepNow() from the IOCtrl module:

http://bricxcc.sourceforge.net/nbc/nxcd ... tions.html

I doubt there is any significant difference in what the firmware does when you turn off the NXT via the IOCtrl module vs turning it off via the UI module (which is where ForceOff lives).

John Hansen

[mattallen37]

Okay, thank you.

Edit: is it fine that I see pixel lines appear and then disappear when turning off the NXT this way (any of the three ways)? How/why does the FW's user menu shut-off not do that?

[afanofosc]

I don't know whether the abrupt shutoff is at all harmful. I'd be surprised if it was but I'm not a hardware guy. Do you see the lines when you use ForceOff?

In c_ui.c there is code like this:

Code: Select all

  // Check for "force" off
  if (IOMapUi.ForceOff != FALSE)
  {
    IOMapUi.ForceOff = FALSE;
    VarsUi.Function  = FUNC_NO_OFF;
    VarsUi.Parameter = MENU_INIT;
    VarsUi.State     = 0;
    IOMapUi.State    = DRAW_MENU;
  }

This causes the firmware to call cUiOff() in Functions.inl:

Code: Select all

UBYTE     cUiOff(UBYTE Action)          // Tell AVR to turn off ARM
{
  if (Action == MENU_INIT)
  {
    switch (VarsUi.State)
    {
      case 0 :                          // Stop VM if running
      {
        if (pMapCmd->ProgStatus == PROG_RUNNING)
        {
          pMapCmd->DeactivateFlag = TRUE;
        }
        VarsUi.State++;
      }
      break;

      case 1 :                          // When VM is stopped -> Display off and close all connections
      {
        if (pMapCmd->ProgStatus != PROG_RUNNING)
        {
          pMapDisplay->Flags     &= ~DISPLAY_ON;
          VarsUi.BTCommand        = (UBYTE)DISCONNECTALL;
          VarsUi.BTPar1           = (UBYTE)0;
          VarsUi.BTPar2           = (UBYTE)0;
          pMapComm->pFunc(VarsUi.BTCommand,VarsUi.BTPar1,VarsUi.BTPar2,0,NULL,&(VarsUi.BTResult));
          VarsUi.State++;
        }
      }
      break;

      case 2 :                          //  Send off command to AVR
      {
        if (VarsUi.BTResult != INPROGRESS)
        {
          pMapIoCtrl->PowerOn   = POWERDOWN;
          VarsUi.Timer          = 0;
          VarsUi.State++;
        }
      }
      break;

      case 3 :                          // Wait for power off
      {
        if (++VarsUi.Timer >= ARM_WAIT_FOR_POWER_OFF)
        {
          VarsUi.State++;
        }
      }
      break;

      case 4 :                          // Vitual off state (if still power) wait for on button
      {
        pMapIoCtrl->PowerOn     = 0;
        if (BUTTON_ENTER == cUiReadButtons())
        {
          VarsUi.State++;
        }
      }
      break;

      default :                         // Turn on again
      {
        IOMapUi.State           = INIT_DISPLAY;
        VarsUi.State            = 0;
      }
      break;

    }
  }

  return (VarsUi.State);
}

So you could do something to the display flags before calling PowerDown().

Code: Select all

  SetDisplayFlags(0); // should turn off the display, disable refresh, use normal memory
  Wait(MS_1); // give firmware a chance to process the previous IOMap change
  PowerDown(); // turn off

I am pretty sure that the display will be properly reset to default values when you turn the NXT back on.

John Hansen

[mattallen37]

That makes no difference, even waiting 5ms.

[mightor]

I am not sure why you are worried Considering the NXT doesn't get messed up if you yank the batteries out, I doubt the firmware will do anything worse than that.

- Xander

[mattallen37]

At this point, it's not so much that I am worried, as I am curious how the FW user menu doesn't make the lines on the screen.