Arty A7

Tags: arch:riscv vendor:sifive experimental

Todo

There is currently no support for GPIO, SPI, I2C, RTC, WDT or PWM. There is also no support for RISC-V user mode yet. If you are interested in contributing one of these features, please see Contributing.

The Arty A7 is an Artix 7 FPGA development board. There is some external documentation about the board itself (and its datasheets) here.

Features

450MHz internal clock
16MB QSPI flash
10/100Mbps Ethernet
256MB DDR3 @333MHz
JTAG programmable
5200 logic slices
1800Kbits of block RAM

Buttons and LEDs

The board has:

4 switches
4 buttons
1 RESET LED
1 User LED
4 User RGB LEDs

Power Supply

The board can be supplied power over USB, or a 7-15V 2.5mm coaxial supply. The logic level of the A7 is 3V3.

Installation

You will need to download the tool-chain for this board:

$ curl https://static.dev.sifive.com/dev-tools/riscv64-unknown-elf-gcc-8.3.0-2019.08.0-x86_64-linux-ubuntu14.tar.gz

Flashing

Follow the instructions on https://github.com/enjoy-digital/litex to build the vexriscv softcore fpga gateware and flash to Arty A7 board:

$ cd litex-boards/litex_boards/targets
$ ./digilent_arty.py --with-ethernet --with-sdcard --uart-baudrate 1000000 --cpu-type=vexriscv --cpu-variant=secure --build --load --flash

Next, set up a TFTP server on your host machine, copy nuttx.bin to your tftpboot directory and change its name to boot.bin.
Setup the wired connection (UART and TFTP) between your A7 board and host machine.
Run the following command:
```
$ minicom -b 1000000 /dev/ttyUSB1 # The default baudrate on litex vexriscv is 1e6
```
When you see the bios prompt litex>, type netboot and press “Enter”. You should then see the NSH prompt.

Configurations

You can configure NuttX for this board using:

$ ./tools/configure.sh arty_a7:<config>

Where <config> is the name of one of the configurations listed below.

nsh

A simple configuration with the NSH shell.