[](https://crates.io/crates/longan-nano)
[](https://crates.io/crates/longan-nano)
[](https://travis-ci.org/riscv-rust/longan-nano)
# `longan-nano`
> Board support crate for the Longan Nano board
## [Documentation](https://docs.rs/crate/longan-nano)
## Getting started
### Installing dependencies
- Rust 1.36 or a newer toolchain. e.g. `rustup default stable`
- `rust-std` components (pre-compiled `core` crate) for the RISC-V target. Run:
``` console
rustup target add riscv32imac-unknown-none-elf
```
- RISC-V toolchain ([e.g. from SiFive](https://static.dev.sifive.com/dev-tools/riscv64-unknown-elf-gcc-8.1.0-2019.01.0-x86_64-linux-ubuntu14.tar.gz))
One of:
- [dfu-util](http://dfu-util.sourceforge.net/)
- [openocd for GD32VF103](https://github.com/riscv-mcu/riscv-openocd)
- [RV-LINK](https://gitee.com/zoomdy/RV-LINK)
When using `dfu-util`, the entire RISC-V toolchain is not necessary. Only `objcopy` from [riscv-binutils-gdb](https://github.com/sifive/riscv-binutils-gdb.git) is needed.
It can be compiled with the following commands:
```
git clone https://github.com/sifive/riscv-binutils-gdb.git
cd riscv-binutils-gdb
./configure --target=riscv64-unknown-elf --disable-werror --with-python=no --disable-gdb --disable-sim --disable-libdecnumber --disable-libreadline --with-expat=yes --with-mpc=no --with-mpfr=no --with-gmp=no
make
```
It will provide the `binutils/objcopy` tool needed to convert the compiled Rust binary into `firmware.bin` (note: this works on arm64 as well).
### Building
If you have a GD32VF103C**B** chip on your board, edit `.cargo/config` and replace
`memory-c8.x` with `memory-cb.x`.
To build all the provided examples run
```
cargo build --examples --release --all-features
```
### Using dfu-util for Flashing
The GD32VF103 contains a [DFU](https://www.usb.org/sites/default/files/DFU_1.1.pdf)
compatible bootloader which allows to program the firmware of your longan-nano without
additional hardware like a JTAG adapter; instead just using an ordenary USB-C cable.
You can use [dfu-util](http://dfu-util.sourceforge.net/) or the vendor supplied tool to
flash the firmware.
Unfortunately, some versions of this chip shipped with a buggy bootloader and it won't report
the correct parameters to flash it sucessfully. As of May 2020, the most recent version of
[dfu-util](http://dfu-util.sourceforge.net/) from the git repository contains a workaround.
Make sure you use an up-to-date version.
See [this issue](https://github.com/riscv-rust/longan-nano/issues/5) for details.
Steps to flash an example via DFU:
1) Extract the binary
```sh
riscv-nuclei-elf-objcopy -O binary target/riscv32imac-unknown-none-elf/release/blinky firmware.bin
```
2) Flash using `dfu-util`:
Keep the BOOT0 button pressed while power-up or while pressing and releaseing the reset button. Then
run
```sh
dfu-util -a 0 -s 0x08000000:leave -D firmware.bin
```
Ensure that dfu-util uses a page size of 1024; either because your GD32VF103 has
a bootloader without the the aforementioned bug, or because the output reads
```
[...]
Device returned transfer size 2048
DfuSe interface name: "Internal Flash "
Found GD32VF103, which reports a bad page size and count for its internal memory.
Fixed layout based on part number: page size 1024, count 128.
Downloading to address = 0x08000000, size = 23784
[...]
```
### Using OpenOCD for Flashing and Debugging
Start openocd assuming you have Sipeed JTAG adapter:
```sh
/path/to/openocd -f sipeed-jtag.cfg -f openocd.cfg
```
Run one of the examples:
```sh
cargo run --example blinky
```
or
```sh
cargo run --release --example ferris --features lcd
```
### Using RV-LINK for Flashing and Debugging
[RV-LINK](https://gitee.com/zoomdy/RV-LINK) is a Chinese firmware, similar to
[Black Magic Probe (BMP)](https://github.com/blacksphere/blackmagic/wiki). It
supports the Longan Nano, allowing to use one Longan Nano board as a debug
probe for another one. It can be built & flashed via
[PlatformIO](https://platformio.org/). Check out the latest version to ensure
that the code compiles:
```
> git clone https://gitee.com/zoomdy/RV-LINK
> cd RV-LINK
> git tag
v0.0.1
v0.1
v0.2 # <- seems to be the latest tag, so let's check this out
> git checkout tags/v0.2
```
PlatformIO allows building & flashing of firmware with a single command. To do
so, the board needs to be in bootloader mode (DFU mode). The board boots to
bootloader mode if the bootloader button is pressed while powering it up (e.g.
by plugging it in). However, it is also possible to enter bootloader mode
without un- and replugging the board: press the boot button, press the reset
button, release the reset button and finally release the boot button while the
board is plugged in.
```
> pio run -t upload # put the board in bootloader mode before
```
Once RV-LINK is flashed to your probe, connect the eight debug pins on the
probe with the debug pins on the debug target. Ensure that you connect the pins
according to this table:
| Probe Pin | Target Pin |
| --- | --- |
| JTDO | JTDO |
| JTDI | JTDI |
| JTCK | JTCK |
| JTMS | JTMS |
| 3V3 | 3V3 |
| GND | GND |
After you connected the debug probe to your host, a new serial port shows up.
You can connect GDB to this serial port as an `extended-remote`. For
predictable behavior when multiple serial devices are present (and hence
`/dev/ttyACM0` is not necessarily the RV-LINK device),
[udev](https://www.freedesktop.org/wiki/Software/systemd/) offers id symlinks.
However you may also use `/dev/ttyACM0` or even `COMx` if you run Windows.
```
> gdb
(gdb) target extended-remote /dev/serial/by-id/usb-RV-LINK_Longan_Nano_GD32XXX-3.0.0-7z8x9yer-if00
```
To flash the firmware, execute `load` in GDB:
```
> gdb target/remote/debug/demo
(gdb) target extended-remote /dev/ttyACM0
(gdb) monitor reset halt
(gdb) load
(gdb) monitor reset
```
To improve your workflow, you can put the aforementioned GDB commands in
a `debug.gdb` file and add these lines to `.cargo/config`:
```
[target.riscv32imac-unknown-none-elf]
runner = 'gdb -command=debug.gdb'
```
This way `cargo run --target riscv32imac-unknown-none-elf` will automatically
launch GDB, flash your firmware on the target and provide you with a full debug
environment.
You can infer the current status of the board by observing the blinking pattern
of the green LED:
| Blink Behavior | Probe Status |
| --- | --- |
| Short pulse, on for 100ms, off for 900ms | GDB is not connected |
| Slow flashing, on for 500ms, off for 500ms | GDB is connected and the debugged MCU is in halt state |
| Fast blinking, on for 100ms, off for 100ms | GDB is connected, and the debugged MCU is running |
| Long pulse, on for 900ms, off for 100ms | RV-LINK has failed. Retry after resetting RV-LINK |
## License
Copyright 2019-2020 [RISC-V team][team]
Permission to use, copy, modify, and/or distribute this software for any purpose
with or without fee is hereby granted, provided that the above copyright notice
and this permission notice appear in all copies.
THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF
THIS SOFTWARE.
## Code of Conduct
Contribution to this crate is organized under the terms of the [Rust Code of
Conduct][CoC], the maintainer of this crate, the [RISC-V team][team], promises
to intervene to uphold that code of conduct.
[CoC]: CODE_OF_CONDUCT.md
[team]: https://github.com/rust-embedded/wg#the-risc-v-team