longan nano

This is an example app for Longan Nano (GD32V) board. It uses mdepx rtos.

This app reads data from CO2 sensor and shows it on the LCD display.

Bill of materials:

1. Longan Nano https://www.aliexpress.com/wholesale?SearchText=longan+nano
2. MH-Z19B sensor https://www.aliexpress.com/wholesale?SearchText=MH-Z19B
3. SiPEED debugger (optional) https://www.aliexpress.com/wholesale?SearchText=RISC-V+Debugger

Connect your MH-Z19B Co2 sensor as this:

mh-z18b	longan nano
TX	A3
RX	A2
Vin	5V
GND	GND

Build project

$ git clone --recursive https://github.com/machdep/longan-nano
$ cd longan-nano
$ export CROSS_COMPILE=/opt/riscv/bin/riscv32-unknown-elf-
$ make clean all

Build openocd to use with SiPEED debugger

$ git clone https://github.com/bukinr/riscv-openocd
$ cd riscv-openocd
$ ./bootstrap
$ ./configure
$ make

Program the chip using OpenOCD

$ /path/to/riscv-openocd/src/openocd -f ./sipeed-jtag.cfg -f ./openocd.cfg -c "program obj/longan-nano.elf; exit"

Alternatively (without SiPEED debugger), program using DFU

Get dfu-util.

Boot your longan-nano in DFU bootloader mode. For this keep boot0 button pressed and then press and release the reset button.

In a DFU mode run this command:

$ sudo ./dfu-util -a 0 -s 0x08000000:leave -D obj/longan-nano.bin

Press the reset button on the longan nano after programming.

Note that programming using sipeed debugger is 1-2 seconds faster compare to dfu-util.