We’ve got plenty of ultra low cost , media capable Linux boards in recent years, but most of those are based on Arm architecture. More recently RISC-V open source ISA has started to show up in various boards such as Sipeed M1, but none of those can play video, or at least don’t come with an hardware video decoder.
C-Sky Linux development board does change that somewhat. It’s sold for about $6 (39 RMB) on Taobao, and $17.36 shipped on Aliexpress, and features Nationalchip GX6605S processor for DVB-S2 HD set-top boxes using C-SKY architecture, independent from RISC-V, although C-SKY is also a member of the RISV-C foundation.
C-SKY Linux development board key features and specifications:
- SoC – Nationalchip GX6605S C-SKY ISA V1 CK610M 32-bit processor @ 574 MHz with 64MB DDR2 RAM, built-in DVB-S2/S demodulator
- Storage – 4MB SPI flash for bootloader and media player program
- Video Output – HDMI output up to 1080p; framebuffer resolution (for UI): 1280×720
- Video Playback – H.264 up to 1080p
- USB – 2x USB2.0 host ports
- Expansion – 5-pin header with 3x GPIOs, 3.3V, GND
- JTAG via XX32F103C8T6 USB-JTAG chip (micro USB port)
- UART console via CH340g USB-UART chip (micro USB port)
- Misc – 5 user buttons, reset button, 4x LEDs
- Power Supply – 5V/1A via micro USB port (JTAG or UART)
There’s no network connectivity nor large storage on the board – everything runs from the 4MB SPI flash, but you can add Ethernet, WiFi, and/or storage via the USB ports.
Documentation – mostly in Chinese – is available on Github.io, and support provided via Github issues tracker. Their Linux 4.16 based firmware is build with buildroot + uClibc-NG, and you can run it in qemu if you don’t have the board. You’ll also find documentation about C-SKY architecture, and the architecture has also recently been submitted and approved to the mainline kernel.
Thanks to Zoobab for the tip.