46a373e2f5
Bump kernel revision used by lego_ev3_defconfig to the latest tag from ev3dev, as suggested by Peter. This is a 4.4 series kernel, which has the added benefit of not necessitating a specific gcc to boot. We need a patch to create an empty drivers/lego/Kconfig file for the build to succeed though, as the ev3dev kernel normally expects a drivers tree to be checked out there. Signed-off-by: Vincent Stehlé <vincent.stehle@laposte.net> Suggested-by: Peter Korsgaard <peter@korsgaard.com> Reviewed-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be> Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
132 lines
3.2 KiB
Plaintext
132 lines
3.2 KiB
Plaintext
Lego Mindstorms EV3
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Intro
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=====
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This is the buildroot basic board support for the Lego Mindstorms EV3
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programmable brick. No support for sensors and drivers is provided for the
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moment.
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The Lego Mindstorms EV3 brick comprises a Texas Instruments AM1808 SoC, with
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an ARM 926EJ-S main processor running at 300 MHz.
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See:
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- https://en.wikipedia.org/wiki/Lego_Mindstorms_EV3
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- http://www.lego.com/en-us/mindstorms/products/ev3/31313-mindstorms-ev3/
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- http://www.ti.com/product/am1808
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The buildroot configuration uses the Linux kernel of the ev3dev project.
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See:
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- https://github.com/ev3dev/ev3-kernel/
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- http://www.ev3dev.org/
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How it works
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============
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Boot process :
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--------------
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The u-boot on-board the EV3 brick has provision to boot a Linux kernel from the
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external µSD card. It will try to load a uImage from the first µSD card
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partition, which must be formatted with a FAT filesystem.
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How to build it
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===============
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Configure Buildroot
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-------------------
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The lego_ev3_defconfig configuration provides basic support to boot on the Lego
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Mindstorms EV3 programmable brick:
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$ make lego_ev3_defconfig
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Build everything
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----------------
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Note: you will need to have access to the network, since Buildroot will
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download the packages' sources.
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$ make
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Result of the build
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-------------------
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After building, you should obtain this tree:
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output/images/
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├── rootfs.ext2
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├── rootfs.ext3 -> rootfs.ext2
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└── uImage
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Prepare your SDcard
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===================
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The following µSD card layout is recommended:
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- First partition formatted with a FAT filesystem, containing the uImage.
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- Second partition formatted as ext2 or ext3, containing the root filesystem.
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Create the SDcard partition table
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----------------------------------
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Determine the device associated to the SD card :
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$ cat /proc/partitions
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Let's assume it is /dev/mmcblk0 :
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$ sudo fdisk /dev/mmcblk0
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Delete all previous partitions by creating a new disklabel with 'o', then
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create the new partition table, using these options, pressing enter after each
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one:
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* n p 1 2048 +10M t c
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* n p 2 22528 +256M
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Using the 'p' option, the SD card's partition must look like this :
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Device Boot Start End Blocks Id System
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/dev/mmcblk0p1 2048 22527 10240 c W95 FAT32 (LBA)
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/dev/mmcblk0p2 22528 546815 262144 83 Linux
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Then write the partition table using 'w' and exit.
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Make partition one a DOS partition :
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$ sudo mkfs.vfat /dev/mmcblk0p1
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Install the binaries to the SDcard
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----------------------------------
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Remember your binaries are located in output/images/, go inside that directory :
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$ cd output/images
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Copy the Linux kernel:
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$ sudo mkdir /mnt/sdcard
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$ sudo mount /dev/mmcblk0p1 /mnt/sdcard
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$ sudo cp uImage /mnt/sdcard
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$ sudo umount /mnt/sdcard
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Copy the rootfs :
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$ sudo dd if=rootfs.ext3 of=/dev/mmcblk0p2 bs=1M
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$ sync
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It's Done!
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Finish
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======
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Eject your µSD card, insert it in your Lego EV3, and power it up.
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To have a serial console, you will need a proper USB to Lego serial port
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adapter plugged into the EV3 sensors port 1.
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See:
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- http://botbench.com/blog/2013/08/15/ev3-creating-console-cable/
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- http://botbench.com/blog/2013/08/05/mindsensors-ev3-usb-console-adapter/
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The serial port config to use is 115200/8-N-1.
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