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Arduino core extensions for FPGA-based 32-bit MIPS and RISC-V soft CPU cores (f32c).

We have preliminary Boards Manager support. In File->Preferences->Additional Boards Manager URLs enter:

Select pull down menu Tools->Board->Board Manager and instal FPGArduino (cca 100MB).

Arduino needs access to usbserial ports. When user who runs arduino is member of "dialout" groups, then this udev rules might be handy (example from scarab):

# /etc/udev/rules.d/80-fpga-ftdi.rules
# this is for usb-serial tty device
SUBSYSTEM=="tty", ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6010", \
   MODE="664", GROUP="dialout"
# this is for ujprog libusb access
ATTRS{idVendor}=="0403", ATTRS{idProduct}=="6010", \
   GROUP="dialout", MODE="666"


Before upgrading to new version, boards manager cache has to be manually removed by deleting hidden directory 'packages'. If install is attempted with old cache, it will fail with CRC error.

windows cache: %appdata%/Arduino15/staging/packages (use Find files)
linux cache: ~/.arduino15/staging/packages
apple cache: ~/Library/Arduino15/staging/packages

Windows: %appdata%/Arduino15 (open File Explorer, enter %appdata% into the Address Bar and press Enter)

Delete packages directory, then remove/install from boards manager.


Windows 10 DLL problem: ujprog.exe has FTDI DLL dependency. Check this issue for a possible workaround: f32c/tools#4

Some boards need OpenOCD to upload bitstream. OpenOCD has libusb dependency which needs to be manually installed on windows. On Linux libusb is probably already installed. Install libusb on windows only if you need it. To install libusb on windows, easiest way is with Zadig Options->List All Devices Select usb serial device, select driver WinUSB and click install. Zadig is not needed for boards with own uploaders like ULX2S or FleaFPGA. Zadig can have some issues with FTDI drivers for windows 10. Uploader for Numato MimasV2 boards needs Python. On Linux, Python is already installed. On Windows, Python needs to be manually installed.

Manual install: Copy or symlink this to existing arduino directory (versions 1.6.0 and newer), close the Arduino IDE, open it again and new FPGA boards, progammers and examples should appear under pull down menus:

tools->boards-> mips and riscv boards..

tools->programmers->...ujprog openocd etc...


file->examples->...RCswitch...Adafruit GFX/SSD1306..

We had to do small modifications of original examples for AVR-specific or hardware-dependent stuff in order to get them running out of the box on f32c.

Source tree arduino/hardware/fpga contains complete arduino core for unified MIPS and RISC-V achitecture support. Only this directory is needed to be copied to your existing arduino-1.6.x tree. Core can work alone without libraries and examples.

The core comes without GCC for MIPS/RISC-V and tools to upload binary and FPGA bitstreams (ujprog, openocd, JTAGs).

Precompiled binaries for linux and windows with GCC MIPS and RISC-V can be fetched and installed separately, see for further instructions.

There are some short scripts and patches to build GCC from source in

What should work

Blink led :)

Serial (over usb-ttl adapter, some boards need it external)

Timer (millis(), micros() - 32-bit CPU core clock counter, glitch-free, good for realtime)

GPIO (digitalWrite(), digitalRead())

Interrupts (MIPS only, attachInterrupt() gpio rising/falling edge, timer)

PWM (analogWrite(), analogWriteResolution(), analogWriteFrequency())

Fade (PWM) works on 2 output pins (LEDs).

Software SPI (bitbang, Adafruit OLED library)

Hardware SPI (SD card library)

Software I2C in master mode (SoftwareWire library)

OLED displays SSD1306 compatible (Adafruit SSD1306 library, SPI and I2C)

PID (Proportional-Integral-Derivative controller, fast response, hardware math accellerated, tested on high speed DC motors with encoders)

433.92 MHz transmitter (RCswitch library, Home automation, Remote relays, Garage doors).

FM RDS transmitter 87-108 MHz (RDS message displayed on radio, but PCM sound supported only on ULX2S)

RHT11 Temperature/Humitidy sensors have been reported to work.

SRAM in 8-bit mode (FleaFPGA Uno) and 16-bit mode (ULX2S)

SDRAM in 16-bit mode (Altera DE0 nano, ReVerSE-U16 and Scarab MiniSpartan6+)

LPDDR, DDR, DDR2, DDR3 using Xilinx 7-series MIG and AXI. (ESA11 with DDR3)

What works only on some supported boards

VGA/HDMI/DVI/TV video and audio DMA need either large external RAM (SRAM, SDRAM or DDR) or sufficient BRAM (32K) for use with acram emulation.

Boards with supported external RAM are ULX2S, FleaFPGA Uno, Scarab Minispartan6+, Altera DE0 nano, ReVerSE-U16 and ESA11.

PCM sound depends on DMA. PCM outputs PWM for headphones and FM for reception on 87-108 MHz radio.

Text-to-Speech library TTS depends on PCM. TTS library could be converted to use a simple tongenerator then it will not depend on PCM)

DCF77 transmitter depends on PCM. A proof of concept to adjust longwave RF clocks.

Analog inputs work on FleaFPGA Uno board thanx for contribution.

Pullup digital input control works on FleaFPGA Uno board (it would work on any board but 2 hardware pins must be dedicated for 1 GPIO pin, one of them having pullup resistor)

What doesn't work yet

Hardware I2C slave is not planned soon, as f32c is expected to be an I2C master in most cases.

There's SoftwareWire I2C master which works because F32C is fast enough and has high resolution 32-bit timer.