$25 Sipeed Tang Nano 20K FPGA board can simulate a RISC-V core, run Linux, retro games

The Sipeed Tang Nano 20K is a low-cost FPGA development board based on Gowin GW2AR-18 FPGA with 20,736 logic cells and 64Mbit RAM, which coupled with  64MBit QSPI flash provides enough resources to simulate a 32-bit RISC-V core booting Linux or playing retro games in an emulator.

The FPGA board comes with a USB-C port for power and to load the FPGA bitstream through a BL616 microcontroller that also acts as a USB to serial chip, an HDMI port and an RGB LCD interface for video output, two user buttons, and two rows GPIOs to connect peripherals such as gamepads (through adapters).

Sipeed Tang Nano 20K

Sipeed Tang Nano 20K specifications:

  • FPGA – Gowin GW2A-LV18QN88C8I7 with
    • 20,736 logic units (LUT4)
    • 15,552 flip-flops (FF)
    • RAM
      • 41,472 shadow SRAM (S-SRAM)
      • 828K block SRAM (B-SRAM)
      • Numbers of B-SRAM – 46
      • 64Mbit 32-bit SDR SDRAM
    • 48x 18×18 multipliers
    • 2x PLLs
    • 8x I/O Bank
  • Onboard debugger – Bouffalo Labs BL616 32-bit RISC-V CPU (RV32IMAFCP) @ up to 320 MHz, 480KB SRAM, embedded flash for
    • JTAG for FPGA
    • USB to UART for FPGA
    • USB to SPI for FPGA communication
    • Control frequency generated by the MS5351
  • Clock generator – MS5351 provides 3 extra clocks for the FPGA
  • Storage – 64Mbit QSPI flash to save the FPGA bitstream, microSD card slot for data
  • Display interfaces
    • 40-pins RGB LCD connector
    • HDMI port
  • Audio – MAX98357A PCN amplifier, 2-pin header for speaker
  • Expansions – 40-pin GPIO header with SPI, SDIO, I2S, LCD, HDMI EDID, etc…
  • Misc – 6x LEDs, 1x RGB LED (WS2812), 2x user keys, update button
  • Power Supply – 5V via USB-C port
  • Dimensions – 54.04 x 22.55mm

Gowin GW2AR 18 FPGA development board

Sipeed Tang Nano 20K pinout diagram
Sipeed Tang Nano 20K pinout diagram

The company has showcased a 48MHz 32-bit RISC-V VexRiscv softcore (Litex firmware) running on the FPGA and booting a minimal Linux image in the Twitter video embedded below. You’ll also find various samples to control HDMI and RGB LCD interfaces, audio output, UART, and the LEDs on GitHub. Another fun project is the NESTang FPGA Nintendo Entertainment System working on Sipeed Tang Nano 20K and Primer 20K boards. Programming is done through the Gowin IDE, and you’ll find the resources to get started and further hardware documentation (schematics, datasheets, etc…) in the wiki.

Sipeed has just started selling the Tang Nano 20K development board on Aliexpress for $25 and up. You’ll also find accessories there such as 4.3-inch or 5-inch displays, and even a full retro game kit (about $48) with the board, two joysticks with adapters, a breadboard, and a USB cable to run the NESTang bitstream and play some NES games using the HDMI port at 720p resolution and with audio.

Sipeed Tang Nano 20K FPGA gaming kit

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24 Comments
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Jeroen
9 months ago

Why simulate a 48Mhz Risc V when the board has also has a 320Mhz risc embedded?

Tommy Murphy
Tommy Murphy
9 months ago

The terms “simulate” and “emulate” are incorrect and misleading when referring to a soft IP RISC-V *implemented* in FPGA logic.

Addiel Vega
Addiel Vega
9 months ago

I have one, the 9k. However, I don’t seem to find any good tutorials about it. Do you happen to know any?

persondb
persondb
9 months ago

Depending on the core, you could define custom instructions that would use DSPs or other stuff for acceleration purposes and it could be even faster than the 320MHz one.

Or just for easy interface and control with the accelerators inside the FPGA.

Mtk
Mtk
9 months ago

GOWIN offers USB 2.0 SoftPHY IP with support of 480Mbps in USB High Speed mode. It would be useful if such interface is presented as well as some software examples available.

Rogan Dawes
Rogan Dawes
8 months ago

I wonder how many instances it would support concurrently. Could be a nice solution to build a multi-head KVM with, which could also support e.g. media (USB CDROM or USB flash drive) attachment.

Bo Gao
7 months ago

The soft IP won’t last long if you operate it over a wide temperature range. The soft IP core uses IODelay to implement oversampling (there’s no hardware CDR for the USB data lines), and unfortunately the IODelay is not very accurate over PVT, and the current version of USBHS IP doesn’t try to do any dynamic calibrations.

JJJ
JJJ
9 months ago

The chip alone is USD $64 on mouser in qty 168… something is weird about all of the tang boards from sipeed, the cost of the entire board is less than the cost of the FPGA for all of them (by a significant margin). I’m thinking that they get the chips for free?

Mtk
Mtk
9 months ago

I purchased recently form China used GW2AR-LV18 QN88C8/I7 for about 4.70 USD/pcs. Haven’t complete my boards yet, but hope they will work fine. GW2AR evaluation board from Gowin cost about 75 EUR, The price of the chip probably is much lower, but apparently some distributors are trying to make higher profits.

JJJ
JJJ
9 months ago

Where did you buy from specifically?

Mtk
Mtk
9 months ago
Bo Gao
7 months ago

I was given a quote of 45 CNY for sample quantity and 42 CNY for 1k qty by an authorized distributor referred by Gowin’s application engineer. Mouser was asking for a stupid amount of margin on FPGAs, regardless of vendors, probably with Lattice being the only exception.

persondb
persondb
9 months ago

I don’t really get why go with Sipeed/GoWin for FPGA.

You can get cheap Spartan 7 or 6 for around the same price, which would be considerably better or even Lattice alternatives too. For a bit more, you can get a cheap Zynq board too.

See a list of cheap fpgas boards:

http://www.joelw.id.au

Dominik
8 months ago

Which board with Spartan costs around 25$?

megous
8 months ago

Breadboard friendly, lightweight and *fast* SDK!, small, cheap and easy to make random small FPGA projects with. Featureful enough chips. Good balance of I/O on sipeed boards. I hope sipeed continues expanding their gowin line. 🙂

Zynq with its 110+ GiB SDK and 3 minute compile times on 16 core machine for a simple blinky project is really unwieldy.

I guess I have something for all those Chinese manufacturers with win/winner in their name, lol. I kinda like their products.

wojoik
wojoik
9 months ago

orange crab is faster and smaller and have lipo power
and is open source 😉

Dominik
8 months ago

Why do you think is faster? They have similar parameters although Tang Nano 20k has more DSP than Orange Crab. Also the price – 25$ vs 99$ makes a difference 🙂

fanoush
fanoush
8 months ago

Also what do you mean by ‘is opensource’? It is a board with lattice fpga, this is board with gowin fpga, both has schematics available. There is not much difference.

David Willmore
David Willmore
8 months ago

The tools need to be open source, not the board design. Ideally both, I guess, but with closed tools, not much else matters.

fanoush
fanoush
8 months ago

gowin FPGAs have open source toolchain too for nano 1k,4k,9k, check e.g. https://learn.lushaylabs.com/getting-setup-with-the-tang-nano-9k/
20k is a matter of time https://github.com/YosysHQ/apicula/issues/127

Gowin has education version of their IDE/toolchain that works with all Sipeed Tang Nano boards -1k,4k,9k,20k with no license needed https://wiki.sipeed.com/hardware/en/tang/Tang-Nano-Doc/install-the-ide.html

megous
8 months ago

It also has much less I/O. FPGA’s are often useful when you want to acquire/send a lot of data in parallel in a precisely timed manner.

Khadas VIM4 SBC