AVR32 Linux Development/U-Boot
From AVRFreaks Wiki
The STK1000 and NGW100 have 8 MB onboard flash, which is pre-loaded with a bootloader (U-Boot). This bootloader is by default configured to load a Linux kernel from an SD card on STK1000, or onboard flash on NGW100.
The following documentation also applies to NGW100.
NOTE: If the bootloader has been overwritten or needs an upgrade, please refer to the Upgrading U-boot Guide
The U-Boot can be configured via a terminal program by attaching a serial cable to the RS-232 interface on STK1000 marked UART_A. The default communication setting is 115200 bauds, 8 data bits, no parity, 1 stop bit, (8N1). When the STK1000 is powered on, the default configuration is to automatically boot from the SD card after a two second delay. Press space before the two seconds elapse to abort auto-boot and configure U-Boot.
NOTE: The STK1000 bootloader may be configured to only display output on the LCD display. If space is pressed before the two seconds elapse, the user may have to use the watch the LCD display for messages and to change the U-boot configuration.
U-Boot has several configuration (environment) variables that can be changed at the command prompt. Use the printenv
command to view the current settings of these variables.
Uboot> printenv
The variables can be changed with the setenv
command. For instance, the MAC address used for ETH_A can be change as follows:
Uboot> setenv ethaddr "60:87:71:14:cd:ef"
Variables many arguments can also be set with the askenv
command. This example can be used on the STK1000:
Uboot> askenv bootargs Please enter 'bootargs': console=ttyS0 root=/dev/mmcblk0p1 fbmem=600k
Then save and boot:
Uboot> saveenv Uboot> boot
If you have multiple STK1000 cards connected to the network, you should configure different MAC addresses on the cards to avoid network problems.
The default U-Boot environment variables are stored inside the binary. Modifications are stored in RAM, and will be lost when the CPU is reset or powered off. The saveenv command will save the variables to flash, and U-Boot will load these variables from flash the next time it is started.
After configuring, and optionally saving the variables to flash, run the boot command to load the Linux kernel from flash.
For more information about U-boot, please visit Das U-Boot