Maix Bit

Tags: experimental arch:risc-v chip:k210 vendor:sipeed

The Maix Bit development board.

The Maix Bit development board.

The Maix Bit is a RISC-V AI IoT development board.

Features

  • K210 RISC-V AI Chip

  • Dual-core

  • Independent FPU

  • 64-bit

  • 8MB on-chip SRAM

  • Double precision FPU with multiplication, division and square root

Warning

There is currently no support for the FPU, or RISC-V User mode. Peripherals such as GPIO, SPI and I2C are also currently unsupported.

Todo

If you are intersted in using this board, please consider contributing implementations for the above missing features.

Installation

  1. Download and install toolchain and openocd-k210

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

  2. Build openocd-k210

    $ git clone https://github.com/kendryte/openocd-kendryte
$ cd openocd-kendryte
$ ./bootstrap & ./configure & make

Flashing

Download and run NuttX from SRAM (not SPI-Flash):

$ picocom -b 115200 /dev/ttyUSB0
$ sudo ./src/openocd -s ./tcl -f ./tcl/kendryte.cfg -m 0
$ riscv64-unknown-elf-gdb ./nuttx
(gdb) target extended-remote :3333
(gdb) load nuttx
(gdb) c

Write nuttx.bin to SPI-Flash:

$ pip3 install kflash
$ kflash -p /dev/ttyUSB0 -b 1500000 ./nuttx/nuttx.bin

Note

The kflash_gui is not recommended because it’s unstable.

QEMU Process

In order to run this board’s version of NuttX on QEMU, make the following adjustments:

QEMU Installation

Installing and building QEMU can be done with:

$ git clone https://github.com/qemu/qemu
$ cd qemu
$ ./configure --target-list=riscv64-softmmu
$ make
$ sudo make install

Building NuttX for QEMU

Building NuttX follows the same process, but you will need to modify your chosen configuration to include the option CONFIG_K210_WITH_QEMU=y.

Running on QEMU

Run the following:

$ qemu-system-riscv64 -nographic -machine sifive_u -bios ./nuttx

Note

To run Nuttx for kostest, gdb needs to be used to load both nuttx_user.elf and nuttx.

$ qemu-system-riscv64 -nographic -machine sifive_u -s -S
$ riscv64-unknown-elf-gdb -ex 'target extended-remote:1234' -ex 'load nuttx_user.elf' -ex 'load nuttx' -ex 'c'

Configurations

Configurations can be selected using the following configure tool command:

$ ./tools/configure.sh maix-bit:<config>

Where <config> can be replaced by the name of any configuration listed below.

nsh

A simple configuration with NSH running.