| OEMReadData | Reads data from the transport for downloading. |
| OEMEthGetFrame | Reads data from the NIC using function pointer pfnEDbgGetFrame. |
| OEMEthSendFrame | Writes data to the NIC using function pointer pfnEDbfSendFrame. |
| OEMEthGetSecs | Returns number of seconds passed relative to a fixed time. |
The Ethernet support functions use callbacks into network controller-specific routines. This means that you must implement additional routines and set up appropriate function pointers in the OEMPlatformInit function if you want to support a different network controller, as demonstrated in the following sample code:
cAdaptType=pBootArgs->ucEdbgAdapterType;
// Set up EDBG driver callbacks based on
// Ethernet controller type.
switch (cAdaptType) {
case EDBG_ADAPTER_NE2000:
pfnEDbgInit = NE2000Init;
pfnEDbgInitDMABuffer = NULL;
pfnEDbgGetFrame = NE2000GetFrame;
pfnEDbgSendFrame = NE2000SendFrame;
break;
case EDBG_ADAPTER_DP83815:
pfnEDbgInit = DP83815Init;
pfnEDbgInitDMABuffer = DP83815InitDMABuffer;
pfnEDbgGetFrame = DP83815GetFrame;
...
}
Flash Memory Support
Having implemented network communication capabilities, you also must enable the boot loader to download run-time image onto the new hardware platform and pass control to it. Alternately, you can save the run-time image to flash memory. Table 5-4 lists the download and flash memory support functions that you must implement for this purpose if the reference BSP's boot loader does not already support these features.
Table 5-4 Functions for supporting download and flash memory
| Function | Description |
|---|---|
| OEMPreDownload | Sets up the necessary download protocol supported by platform builder. |
| OEMIsFlashAddr | Checks if the image is for flash or RAM. |
| OEMMapMemAddr | Performs temporary remapping of the image to RAM. |
| OEMStartEraseFlash | Prepares to erase flash of enough size to fit the OS image. |
| OEMContinueEraseFlash | Continue erasing flash based on download progress. |
| OEMFinishEraseFlash | Complete the flash erasing once the download is done. |
| OEMWriteFlash | Write OS image to flash. |
User Interaction
Boot loaders can support user interaction based on a menu that provides the user with different options to start the platform, which can be helpful during the development process and later on for maintenance and software updates. Figure 5-4 shows a standard boot loader menu. For sample source code, check out the Menu.c file located in the SrcBootloaderEboot directory of a reference BSP or in the %_WINCEROOT%PlatformCommonSrc CommonBootBlmenu folder.
Figure 5-4 An example of a boot loader menu
Additional Features
