NixOS on Pinecube (Early work in progress)

Build an SD card image with ./build.sh. Prebuilt image here. (updated 2020-10-18) Decompress and flash with:

$ cat ./result/sd-image/nixos-sd-image-21.03pre-git-armv7l-linux.img.zst | zstd -d | dd of=/dev/<sdcard> bs=1024

Should be accessible over UART2 pins (see pinout on wiki) or SSH.

• Username: nixos
• Password: nixos

Additional Notes

Recording from CSI camera:

• https://linux-sunxi.org/CSI#CSI_on_mainline_Linux_with_v4l2
• https://www.kernel.org/doc/html/latest/userspace-api/media/v4l/subdev-formats.html

Streaming via rtmp:

$ media-ctl --set-v4l2 '"ov5640 1-003c":0[fmt:UYVY8_2X8/640x480@1/15]'
$ ffmpeg -s 640x480 -r 15 -i /dev/video0 -vcodec flv -f flv rtmp://192.168.1.200/live/pinecube

On receiving machine:

$ mpv "rtmp://192.168.1.200/live/pinecube" --profile=low-latency --cache-secs=1

Activating LEDs:

https://elinux.org/CI20_GPIO_LED_Blink_Tutorial#Controlling_GPIOs_from_the_shell_.28Linux.27_sysfs_interface_for_GPIOs.29

$ echo 1 > /sys/class/leds/pine64\:ir\:led1/brightness

(Except they seem to be reversed. Setting 0 brightness turns them on, setting 1 turns them off) Change it to ACTIVE_HIGH in dtb?

GPIO:

https://linux-sunxi.org/GPIO

$ cat /sys/kernel/debug/pinctrl/1c20800.pinctrl/pinmux-pins

gives information about pin numbering and what pins already claimed for other things

Enabling/disabling IR-cut filter

# Export gpio, set direction
$ echo 45 > /sys/class/gpio/export
$ echo out > /sys/class/gpio/gpio45/direction

# 1 to enable, 0 to disable
$ echo 1 > /sys/class/gpio/gpio45/value

Passive IR detection

# Export gpio, set direction
$ echo 199 > /sys/class/gpio/export
$ echo in > /sys/class/gpio/gpio199/direction

# Returns 1 for presence, 0 for none
$ cat /sys/class/gpio/gpio199/value

SPI NOR

dmesg error: spi-nor spi0.0: unrecognized JEDEC id bytes: 0b 40 18 0b 40 18

Ethernet

Working fine in linux. U-boot needs support

WIFI

Dmesg errors:

Oct 19 06:11:31 nixos wpa_supplicant[926]: Successfully initialized wpa_supplicant
Oct 19 06:11:32 nixos kernel: sunxi-mmc 1c10000.mmc: data error, sending stop command
Oct 19 06:11:32 nixos kernel: sunxi-mmc 1c10000.mmc: send stop command failed

Audio

Is not in currently in DTB at all. Maybe use sun7i-a20 as example. It has a "codec" block. See the S3 manual, grep for I2S/PCM.