NET+OS Bootloader Overview Requirements How to Build How to Customize Changes to Applications Configuration Settings

Features Recovers when flash update fails Application image is compressed Uses DHCP or BOOTP to get an IP address Uses TFTP to download new firmware

Normal Operation Bootloader always runs at Power Up Uses standard BSP initialization code Performs 32-bit CRC checksum of application image Decompresses Application from flash to RAM Starts Application

Recovery Mode Triggered if Application Image fails CRC checksum Uses DHCP/BOOTP to get an IP address Uses TFTP to download a new application Image Writes application image to flash Resets the unit

Structure of Flash ROM Bootloader stored in first 64K of flash Last sector of flash may be used for NVRAM storage Rest of flash is used to hold application image Customers can create more sections

Requirements DHCP or BOOTP Server TFTP Server TFTP must be on the same machine as the DHCP/BOOTP server

DHCP/BOOTP Server Setup Must supply boot filename, which is used as the name of the firmware image to download Bootloader will reject offers that don’t have a boot filename Must also supply an IP address Should supply a gateway and subnet mask

Lock Bootloader Sectors Booloader image must be written into start of flash at the factory Sectors that contain the bootloader must be locked at the factory to prevent accidental erasure Lock method depends on flash part

How to Build for Green Hills Configure the BSP Build the BSP Build the RAM image of the bootloader Build the ROM image of the bootloader Bootloader is in netos\src\bootloader

How to Build for MicroCross Configure the BSP Build the BSP Build “make all” in the bootloader directory

How to Customize Customization hooks in customize.c Customize.c contains a default implementation of the bootloader Custom features are added by modifying functions in customize.c These functions were written to be easy to customize

Example static char *getDefaultFilename(void) { static char *defaultFilename = ""; return defaultFilename; }

How to Change default Filename Default filename is sent to DHCP/BOOTP server as a hint about what file the unit wants to download Standard implementation is to send an empty string Change getDefaultFilename() to supply a default boot filename

Change Error Reporting Default implementation blinks LEDs in a pattern to indicate error condition Edit reportError() to change this

Determine when to Update Image Default implementation is to update the image if it fails a 32-bit CRC checksum test Might want to look at buttons or switches too Change shouldDownloadImage()

Determine if Image is Valid Need to determine if image downloaded from TFTP server is valid Default implementation performs a 32-bit CRC checksum of it Might need to prevent users from upgrading cheap units with firmware from expensive ones Edit isImageValid()

Might not want to use DHCP Default implementation uses DHCP/BOOTP to get an IP address and name of TFTP image to download Might want to get this information in a different way Can change downloadImage() to do this

Exchanging Additional Information May want to send additional information to the DHCP server, or have it send additional information to the unit Can customize downloadImage() to send Vendor Class ID (60) to DHCP server DHCP server can send Vendor Info (43) to unit

Changes to NAFTPAPP NAFTPAPP looks at filename to determine where to write image into flash Image.bin is written into application image space in flash Rom.bin is written to start of flash

Changes to Applications Debug, romzip, and ramzip images are gone The “Image” image replaces all of them Creates debug version that corresponds to the image the bootloader will execute Also creates compressed version that can be written to flash and executed by the bootloader

Structure of Application Image Image that is written to flash has a header Header is created by boothdr.exe Image is usually compressed Generated automatically when “image” is generated

Boothdr.exe Used to generate image that is written to flash Adds header and 32-bit CRC checksum Compresses application image boothdr [ ]

Boothdr Config File Used to set values in bootloader header Default version stored in linkerScripts\bootldr.dat Customers can override this by editing build or make files to use a different one

Default Boothdr Config File WriteToFlash Yes Compressed Yes ExecuteFromRom No flashOffset 0x10000 ramAddress 0x MaxFileSize 0xD0000

Customized Headers Customers can append their own headers onto the bootloader header Useful for identifying the H/W requirements of the firmware Custom header is appended by adding the name of a header file onto the command line used by boothdr.

New BSPCONF.H Settings BSP_BOOTLOADER_SIZE determines the size of the bootloader image in flash BSP_APPLICATION_OFFSET determines where the application image starts in flash BSP_APPLICATION_IMAGE_SIZE determines the maximum size of the application image in flash