WinCE

• Familiarize yourself with the datasheet of the processor which you are using (I have been working on PXA27x on sometime, so will explain based on that).
• Prepare some assembly level (or C if you are not familair with assembly routines), which you can run on ICE and check the hardware. Especially whether you are able to access the new SDRAM.
• Run some preliminary tests on the SDRAM like writing certain portions of and verifying it.
• Scrutinize and tune the SDRAM timing values as they play a very important role in system's performance.

• The memory initialisation for 16-bit interface
• The oem address table change (if required to change the SDRAM size)
• Memory parameters in the BIB files (especially config_cebase.bib)
  

In display drivers, DrvEscape is a function to retrieve information from a device that is not available in DDI for example, issuing a DrvEscape to the PXA27X display driver with GETGXINFO parameters will fill in the GAPI data structure.

For accessing the DrvEscape routines, the following code segment can be used:

  {
          HDC hDC = NULL;
          DWORD Status;
          CEDEVICE_POWER_STATE pwrState = D0;
          hDC = CreateDC(NULL, NULL, NULL, NULL);
          if (NULL != hDC)
          {
             pwrState = D0;
             Status= ExtEscape(hDC, IOCTL_POWER_SET,
                                  0, NULL,
                                  sizeof(pwrState), (LPSTR)&pwrState );
              ReleaseDC(NULL,hDC);
          }
      }

For checking whether the bluetooth stack is up and initialised, you can make use of the manual reset event BTH_NAMEDEVENT_STACK_INITED (L"system/events/bluetooth/StackInitialized").

You can get more information on this page.

If you are experiencing system performance issues in ROM based File systems, here is a nice tweak to boost up the performance. Most of the times, this slowdown will be due to constant registry flushing in to ROM in background.

[HKEY_LOCAL_MACHINE\init\BootVars]
"RegistryFlags"=dword:2

In one of my previous posts, I mentioned about cloning OALIOCTL, was thinking of writing about it. But Bruce have already written about. And it was my reference too. So check it out

It is assumed that , the OAL code is cloned to the BSP under development, including the ioctl code. For the purpose of explaining the process, the Mainstone III reference platform will be used.

The BSP specific, ioctl will be located under the directory, MAINSTONEIII\SRC\OAL\OALLIB\ioctl.c.

Now lets assume that we need to implement an ioctl to flag the backing up of system alarm setting during shutdown.

• Define a new function in ioctl.c as:

BOOL OALIoCtlHalAlarmSet
               (   UINT32 code, VOID *pInpBuffer,
                   UINT32 inpSize, VOID *pOutBuffer,
                 UINT32 outSize, UINT32 *pOutSize)
{
g_oalIoCtlUserAlarmSet = TRUE;
return(TRUE);
}

• Define a macro for the new IOCTL.

#define FILE_DEVICE_CUST_OEM   32806

#define IOCTL_DDK_SET_ALARM_FLAG        \
CTL_CODE(FILE_DEVICE_CUST_OEM, 0x0100, METHOD_BUFFERED, FILE_ANY_ACCESS)

• Modify g_oalIoCtlTable variable in ioctl.c to add the new ioctl mapping:

const OAL_IOCTL_HANDLER g_oalIoCtlTable[] = {
.....
{
IOCTL_DDK_SET_ALARM_FLAG,
0,
OALIoCtlHalAlarmSet
},
#include 
.....
}

On resuming from sleep mode of PXA27X, the usb client wont be working straight away. No insertion events will be detected and the device will be shown as an uknown device in PC.

For overcoming this situation, we have to clear the OTGPH bit in PSSR (Power Manager Sleep Status Register). This is a write to clear bit.

OTGPH will be set when entering sleep mode when writing the PWRMODE register and indicates that the OTG pad is retaining state. So after resuming, the USB OTG, UDC and UHC should be configured, then only clear the OTGPH bit.

Referece : Marvell PXA27X Processor Developer Manual, November 3 , 2006

For monitoring events for a network interface, the notification request ioctl IOCTL_NDISUIO_REQUEST_NOTIFICATION in NDISUIO driver can be used.

By using this Notification mechanism, we can capture events for each network interface in Windows CE such as

• Bind
• Unbind
• Power Up
• Power down
• etc...

In power manager, the PDD has a certain set of events that it monitors. For eg:

• PM_BOOTPHASE2_EVENT
• PM_SYSTEM_API_EVENT etc

  HANDLE hSysTmrReset = CreateEvent(NULL, FALSE, FALSE, _T("PowerManager/SystemIdleTimerReset"));
  BOOL bExit = FALSE;
  if (INVALID_HANDLE_VALUE != hSysTmrReset )
  {
      while (FALSE == bExit)
      {
          ResetEvent(hSysTmrReset);
          Sleep(1000);
          SetEvent(hSysTmrReset);
       
          RETAILMSG(TRUE, (TEXT("Reset\r\n")));
          Sleep(20000);
      }
      CloseHandle (hSysTmrReset );
  }
  return 0;

To enable aggressive scanning for wifi network (preferred or non-preferred ones) in Wireless Zero Configuration in Windows CE, use this registry setting:

[HKEY_LOCAL_MACHINE\Comm\WiFi]
ScanInterval: dword:5