- Raspberry Pi 4B
- 7" HDMI+USB Touchscreen
- PiCAN2 hat
- OBD-II to D-SUB adapter
Start by reading : https://github.com/PontusPersson/local_manifests
$ sudo apt install gcc-aarch64-linux-gnu libssl-dev flex build-essential bison
To compile the kernel we need a cross-compile toolchain for arm64.
$ cd $HOME
$ wget https://releases.linaro.org/components/toolchain/binaries/7.5-2019.12/aarch64-linux-gnu/gcc-linaro-7.5.0-2019.12-x86_64_aarch64-linux-gnu.tar.xz
$ tar xvpf gcc-linaro-7.5.0-2019.12-x86_64_aarch64-linux-gnu.tar.xz
First, install prerequisites and merge the android kernel config with the base config for raspberry pi 4 (bcm2711).
$ cd kernel/arpi
$ export PATH=$HOME/gcc-linaro-7.5.0-2019.12-x86_64_aarch64-linux-gnu/bin:$PATH
$ ARCH=arm64 scripts/kconfig/merge_config.sh \
arch/arm64/configs/bcm2711_defconfig \
kernel/configs/android-base.config \
kernel/configs/android-recommended.config \
../../device/arpi/rpi4/can/linux_mcp2515.config
$ ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- make Image.gz -j $(nproc)
$ ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- DTC_FLAGS="-@" make broadcom/bcm2711-rpi-4-b.dtb
$ ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- DTC_FLAGS="-@" make overlays/mcp2515-can0.dtbo
$ ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- DTC_FLAGS="-@" make overlays/vc4-kms-v3d-pi4.dtbo
$ ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- DTC_FLAGS="-@" make overlays/spi0-1cs.dtbo
$ ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- DTC_FLAGS="-@" make overlays/dwc2.dtbo
To get the build to succeed we need to patch the Android framework. Change the files as described in the link below.
https://github.com/android-rpi/device_arpi_rpi4/wiki/arpi-11-:-framework-patch
Continue build referring to http://source.android.com/source/building.html
$ source build/envsetup.sh
$ lunch rpi4car-eng
$ m ramdisk systemimage vendorimage
Partitions of the card should be set-up like followings. Create a MBR partition table.
| # | Size | Partition | Options |
|---|---|---|---|
| p1 | 128MB | boot | set W95 FAT32(LBA) & bootable type |
| p2 | 2048MB | /system | |
| p3 | 128MB | /vendor | |
| p4 | remaining | /data |
Replace mmcblkX with the name of your SD card.
$ sudo fdisk /dev/mmcblk0
Welcome to fdisk (util-linux 2.36).
Changes will remain in memory only, until you decide to write them.
Be careful before using the write command.
Command (m for help): o
Created a new DOS disklabel with disk identifier 0x469e9837.
Command (m for help): n
Partition type
p primary (0 primary, 0 extended, 4 free)
e extended (container for logical partitions)
Select (default p): p
Partition number (1-4, default 1): 1
First sector (2048-124735487, default 2048):
Last sector, +/-sectors or +/-size{K,M,G,T,P} (2048-124735487, default 124735487): +128M
Created a new partition 1 of type 'Linux' and of size 128 MiB.
Command (m for help): p
Disk /dev/mmcblk0: 59,48 GiB, 63864569856 bytes, 124735488 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x6ee618fe
Command (m for help): n
Partition type
p primary (1 primary, 0 extended, 3 free)
e extended (container for logical partitions)
Select (default p): p
Partition number (2-4, default 2): 2
First sector (264192-124735487, default 264192):
Last sector, +/-sectors or +/-size{K,M,G,T,P} (264192-124735487, default 124735487): +2048M
Created a new partition 2 of type 'Linux' and of size 2 GiB.
Command (m for help): n
Partition type
p primary (2 primary, 0 extended, 2 free)
e extended (container for logical partitions)
Select (default p): p
Partition number (3,4, default 3):
First sector (4458496-124735487, default 4458496):
Last sector, +/-sectors or +/-size{K,M,G,T,P} (4458496-124735487, default 124735487): +128M
Created a new partition 3 of type 'Linux' and of size 128 MiB.
Command (m for help): n
Partition type
p primary (3 primary, 0 extended, 1 free)
e extended (container for logical partitions)
Select (default e): p
Selected partition 4
First sector (4720640-124735487, default 4720640):
Last sector, +/-sectors or +/-size{K,M,G,T,P} (4720640-124735487, default 124735487):
Created a new partition 4 of type 'Linux' and of size 57,2 GiB.
Command (m for help): a
Partition number (1-4, default 4): 1
The bootable flag on partition 1 is enabled now.
Command (m for help): t
Partition number (1-4, default 4): 1
Hex code or alias (type L to list all): 0c
Changed type of partition 'Linux' to 'W95 FAT32 (LBA)'.
Command (m for help): p
Disk /dev/mmcblk0: 59,48 GiB, 63864569856 bytes, 124735488 sectors
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disklabel type: dos
Disk identifier: 0x6ee618fe
Device Boot Start End Sectors Size Id Type
/dev/mmcblk0p1 * 2048 264191 262144 128M c W95 FAT32 (LBA)
/dev/mmcblk0p2 264192 4458495 4194304 2G 83 Linux
/dev/mmcblk0p3 4458496 4720639 262144 128M 83 Linux
/dev/mmcblk0p4 4720640 124735487 120014848 57,2G 83 Linux
Command (m for help): w
The partition table has been altered.
Calling ioctl() to re-read partition table.
Syncing disks.
# mkfs.vfat -n boot /dev/mmcblkXp1
# mkfs.ext4 -L userdata /dev/mmcblkXp4
Replace mmcblkX with the name of your SD card.
# dd if=$OUT/system.img of=/dev/mmcblkXp2 bs=1M status=progress
# dd if=$OUT/vendor.img of=/dev/mmcblkXp3 bs=1M status=progress
$ cd /mount/point/of/boot
$ mkdir overlays
$ cp -a $ANDROID_BUILD_TOP/device/arpi/rpi4/boot/* .
$ cp -a $ANDROID_BUILD_TOP/kernel/arpi/arch/arm64/boot/Image.gz .
$ cp -a $ANDROID_BUILD_TOP/kernel/arpi/arch/arm64/boot/dts/broadcom/bcm2711-rpi-4-b.dtb .
$ cp -a $ANDROID_BUILD_TOP/kernel/arpi/arch/arm64/boot/dts/overlays/vc4-kms-v3d-pi4.dtbo ./overlays/
$ cp -a $ANDROID_BUILD_TOP/kernel/arpi/arch/arm64/boot/dts/overlays/spi0-1cs.dtbo ./overlays
$ cp -a $ANDROID_BUILD_TOP/kernel/arpi/arch/arm64/boot/dts/overlays/mcp2515-can0.dtbo ./overlays
$ cp -a $ANDROID_BUILD_TOP/kernel/arpi/arch/arm64/boot/dts/overlays/dwc2.dtbo ./overlays
$ cp -a $OUT/ramdisk.img .
Wow! You made it all the way down here, congratulations!
Now all that's left is to boot your freshly built android automotive device and start hacking away.
If you are really lucky and have a laptop that supports USB-C PD (power delivery) and a good USB-C to USB-C data cable you might be able to both power you device and use adb over the same cable. This is know to work with the cable that I received with my Google Pixel 3 phone and a Lenovo Thinkpad X1 Extreme (Gen 2). Your mileage may vary.
You can also connect to the device trough adb over ethernet of wifi.
adb connect 127.0.0.1 # substitute for the device's ip address
# or if you have mDNS enabled
adb connect Android.local
adb shell
rpi4 #:/
To use the PICan2 HAT together with an OBD-II, first solder the jumpers according to these instructions before mounting it on the raspberry pi: http://skpang.co.uk/catalog/images/raspberrypi/pi_2/PICAN2SMPSUG13.pdf
$ adb shell
rpi4:/ # ip link set dev can0 up type can bitrate 500000
rpi4:/ # candump can0,7e8:7ef &
rpi4:/ # cansend can0 7df#0201050000000000
can0 7E8 [8] 02 41 05 50 00 00 00 00
rpi:/ #
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