1 Summary 2 ======= 3 4 LEGO MINDSTORMS EV3 is a toy robot produced by the LEGO Group. It is based 5 on the davinci da850 evm. The EV3 has a 16MB spi flash and a SDHC microSD card 6 reader. 7 8 Booting 9 ======= 10 11 The EV3 contains a bootloader in EEPROM that loads u-boot.bin from address 0x0 12 of the SPI flash memory (with a size of 256KiB!). Because the EEPROM is read- 13 only and it takes care of low level configuration (PLL and DDR), we don't use 14 U-Boot to produce an SPL image. 15 16 Using the default configuration, U-Boot had a boot scrips that works as follows: 17 18 * Check to see if microSD card is present 19 * If it is, try to load boot.scr from the first FAT partition 20 * If loading boot.scr was successful, run it 21 * Otherwise, try loading uEnv.txt 22 * If loading uEnv.txt was successful, import it 23 * If there is a uenvcmd variable (from uEnv.txt), run it 24 * Try to load uImage from the first FAT partition 25 * If it was successful, try to load da850-lego-ev3.dtb 26 * If loading uImage was successful, boot it (DT is optional) 27 * If none of the above was successful, try booting from flash 28 29 Suggested Flash Memory Layout 30 ============================= 31 32 The following is based on the default U-Boot configuration: 33 34 | Image (file) | Start Addr. | Max. Size | 35 +--------------------+-------------+-------------------+ 36 | u-boot.bin | 0x0 | 0x40000 (256KiB) | 37 | da850-lego-ev3.dtb | 0x40000 | 0x10000 (64KiB) | 38 | uImage | 0x50000 | 0x400000 (4MiB) | 39 | rootfs (squashfs) | 0x450000 | 0xa00000 (10MiB) | 40 41 Writing image to flash 42 ====================== 43 44 The EEPROM contains a program for uploading an image file to the flash memory. 45 The program is started by holding down the right button on the EV3 when powering 46 it on. You can also `run fwupdateboot` in the u-boot shell to reboot into this 47 mode. The image can then be uploaded using the official LEGO MINDSTORMS EV3 48 software or a 3rd party program capable of uploading a firmware file. 49 50 If you are booting from the microSD card, it is enough to just write uboot.bin 51 to the flash. If you are not using a microSD card, you will need to create an 52 image file using the layout described above. 53
