ODROID-C1 was a $35 quad-core SBC from Hardkernel. ODROID-C1 support was introduced in NetBSD 7.0. It has been succeeded by the ODROID-C1+, which is supported by the same NetBSD kernel.

Supported hardware

• CPU: Cortex-A5: Amlogic S805 (4-core) at 1.5GHz
  • CPU frequency scaling is supported with machdep.cpu sysctl tree
  • SMP supported
  • PL310 L2 cache controller
• GIC
• A5 global timer
• Watchdog timer
• "SDHC" and "SDIO" SD/MMC controllers (DMA)
• Serial console
• Framebuffer console
• USB host (OTG)
• Gigabit Ethernet (GMAC)
  • RTL8211F PHY
• Hardware random number generator
• RTC
• GPIO

TODO

• USB device mode
• IR receiver
• I2C
• Audio

Installation (NetBSD 8.0 and later)

• Start with an ARMv7 image from evbarm-earmv7hf/binary/gzimg/ such as armv7.img, the latest is here.
• Build U-Boot for ODROID-C1 https://github.com/jaredmcneill/u-boot-odroid
  • Pre-built binaries here: https://ftp.netbsd.org/pub/NetBSD/arch/evbarm/odroid-c1/u-boot-odroidc-v2011.03-20220520.tar.gz https://ftp.netbsd.org/pub/NetBSD/arch/evbarm/odroid-c1/u-boot.bin.odroidc1
• Write the bootloader to the empty space at the start of the base image:

# dd if=bl1.bin.hardkernel of=armv7.img bs=1 count=442 conv=notrunc
# dd if=bl1.bin.hardkernel of=armv7.img bs=512 skip=1 seek=1 conv=notrunc
# dd if=u-boot.bin.odroidc1 of=armv7.img bs=512 seek=64 conv=notrunc

• Write the image to an SD card.

• Tested 2021-02-19 with NetBSD-current, christos

  • serial fights with ucb keyboard. (avoid by short circuiting cngetc in meson_uart.c to return -1)
  • awge0 does not work reliably (can't even get a dhcp address, stops receiving packets after less than a minute)
  • machine crashes under load

Installation (NetBSD 7.0/7.1)

• Start with an ARMv7 image from evbarm-earmv7hf/binary/gzimg/ such as armv7.img
• Build U-Boot for ODROID-C1 https://github.com/jaredmcneill/u-boot-odroid
  • Pre-built binaries here: https://ftp.netbsd.org/pub/NetBSD/arch/evbarm/odroid-c1/u-boot-odroidc-v2011.03-20220520.tar.gz
• Note the location and size of the FFS partition in the armv7.img disklabel:

# $TOOLDIR/bin/nbdisklabel -M evbarm -B le armv7.img
...
8 partitions:
#        size    offset     fstype [fsize bsize cpg/sgs]
 a:   1359312    385024     4.2BSD      0     0     0  # (Cyl.    188 -    851*)
 b:    262144    122880       swap                     # (Cyl.     60 -    187)
 c:   1744336         0     unused      0     0        # (Cyl.      0 -    851*)
 d:   1744336         0     unused      0     0        # (Cyl.      0 -    851*)
 e:    114688      8192      MSDOS                     # (Cyl.      4 -     59)

• Write the bootloader to the empty space at the start of the base image:

# dd if=bl1.bin.hardkernel of=armv7.img bs=1 count=442 conv=notrunc
# dd if=bl1.bin.hardkernel of=armv7.img bs=512 skip=1 seek=1 conv=notrunc
# dd if=u-boot.bin of=armv7.img bs=512 seek=64 conv=notrunc

• Since the bootloader has overwritten the disklabel, we need to re-add partition "a" from the disklabel to the MBR partition table:

# $TOOLDIR/bin/armv7--netbsdelf-eabihf-fdisk -u armv7.img
...
Which partition do you want to change?: [none] 1
The data for partition 1 is:

sysid: [0..255 default: 169] 
start: [0..109cyl default: 63, 0cyl, 0MB] 385024
size: [0..85cyl default: 1359312, 85cyl, 664MB] 1359312
...
Which partition do you want to change?: [none] 
...
Should we write new partition table? [n] y

• Write the image to an SD card.
• Edit boot.ini on the MS-DOS partition. Note that the default boot.ini has console=fb in bootargs, which you should remove if you want serial console:

ODROIDC-UBOOT-CONFIG

setenv bootargs "root=ld0f awge0.mac-address=${ethaddr} console=fb"
setenv bootcmd "fatload mmc 0:1 0x21000000 netbsd.ub; bootm 0x21000000"
run bootcmd

• On first boot, it will stop because of the wrong device in /etc/fstab. Take this opportunity to grow the root file-system:

# fdisk -u ld0
...
Which partition do you want to change?: [none] 1
The data for partition 1 is:
NetBSD (sysid 169)
    start 385024, size 1359312 (664 MB, Cyls 23/246/32-108/147/55)
        PBR is not bootable: All bytes are identical (0x00)
sysid: [0..255 default: 169]
start: [0..966cyl default: 385024, 24cyl, 188MB]
size: [0..942cyl default: 1359312, 85cyl, 664MB] $
...
Which partition do you want to change?: [none]
...
Should we write new partition table? [n] y
# resize_ffs -y /dev/rld0f
# reboot

• Next boot, create a new /etc/fstab:

# mount -u -o rw /dev/ld0f /
# cat > /etc/fstab << EOF
/dev/ld0f       /               ffs     rw      1 1
/dev/ld0e       /boot           msdos   rw      1 1
kernfs          /kern           kernfs  rw
ptyfs           /dev/pts        ptyfs   rw
procfs          /proc           procfs  rw
tmpfs           /var/shm        tmpfs   rw,-m1777,-sram%25
EOF
# reboot

HDMI

Framebuffer console

Simply add console=fb to the bootargs variable in boot.ini.

Video mode

HDMI video mode can be selected in U-Boot with the video command, e.g.:

odroidc#video dev open 1080P

To make this change permanent, add it to the bootcmd variable in boot.ini:

setenv bootcmd "video dev open 1080P; fatload mmc 0:1 0x21000000 netbsd.ub; bootm 0x21000000"

16 or 24 bpp?

ODROID-C1 defaults to 16bpp. If you want to try 24bpp, add fb.depth=24 to the kernel cmdline options in boot.ini. There are some issues with 24bpp mode and Xorg; see http://gnats.netbsd.org/49812.

Overscan compensation

If you have ODROID-C1 plugged into a TV, the edges of the screen may not be visible. You can scale down the framebuffer console with the hw.genfb0.scale sysctl, e.g.:

# sysctl -w hw.genfb0.scale=95

Setting scale to 100 disables scaling, any other value enables the scaler. Values between 10 and 100 are allowed.

To set this value at boot, you can add fb.scale=95 to the kernel cmdline options in boot.ini.

SYS_LED

The blue SYS_LED on the board is wired to GPIOAO_13. To control the LED from userland, set gpio=YES in rc.conf and add this to /etc/gpio.conf:

gpio4 13 set out sys_led

After rebooting, the LED state can be controlled with gpioctl(8).

# turn the light on
gpioctl gpio4 sys_led on

# turn the light off
gpioctl gpio4 sys_led off

# toggle the light state
gpioctl gpio4 sys_led toggle

U-Boot Environment

To read/write U-Boot environment variables from NetBSD, download and compile the following program: http://ftp.netbsd.org/pub/NetBSD/misc/jmcneill/odroidc1/uenv.c

Automatically booting a backup kernel

These instructions assume the kernels live on eMMC. Adjust devices accordingly for SD card setup.

To setup an ODROID-C1 to fall back to a recovery kernel in the event of a boot failure, install the recovery kernel as /boot/onetbsd.ub.

Create /boot/boot.ini as follows:

ODROIDC-UBOOT-CONFIG
setenv bootargs "root=ld0f awge0.mac-address=${ethaddr}"
fatload mmc 0:1 0x22000000 boot.scr
source 0x22000000

Create /boot/boot.txt:

# regenerate with:
#  mkubootimage -A arm -C none -O netbsd -T script -a 0 -n "NetBSD/odroidc1 boot" boot.txt boot.scr

setenv rescue_kernel "onetbsd.ub"
setenv kernel "netbsd.ub"

if test ${boot_rescue} = false; then
  setenv boot_rescue true
  saveenv
  fatload mmc 0:1 0x21000000 ${kernel}
  mw.l c1109900 0f08ffff        # arm watchdog
  bootm 0x21000000
else
  fatload mmc 0:1 0x21000000 ${rescue_kernel}
  bootm 0x21000000
fi

Generate boot.scr from boot.txt:

mkubootimage -A arm -C none -O netbsd -T script -a 0 -n "NetBSD/odroidc1 boot" /boot/boot.txt /boot/boot.scr

Install the uenv tool from above and add the following to root's crontab:

@reboot                                 /usr/local/sbin/uenv ld0 boot_rescue false

Documentation

Amlogic S805 datasheet: http://dn.odroid.com/S805/Datasheet/S805_Datasheet%20V0.8%2020150126.pdf

ODROID-C1 UART pins

From ODROID Forum:

 ___UART____
|Pin 4 - GND|
|Pin 3 - RXD|
|Pin 2 - TXD|
|Pin 1 - VCC|
\___________|

3.3V LVTTL