jg-fossh / gd32usb2spi

Simple USB-to-SPI adapter firmware using the CDCACM driver. Designed to be used on the Sipeed Tang Premier FPGA board, to establish communication between the GD32F150 on-board processor and the Anlogic FPGA

gd32usb2spi

Simple USB-to-SPI(master) adapter firmware using the CDCACM driver. Designed to be used on the Sipeed Tang Premier FPGA board, to establish communication between the GD32F150 on-board processor and the Anlogic FPGA.

It is recommended to back up the original firmware of the GD32F150 before installing this one.

After installing this firmware with make flash, the GD32F150 on the Tang Premier will contain the following software:

Address	Content	Notes
0x8000000	dapboot	Used to flash the GD32 MCU over DFU
0x8002000	USB-to-JTAG	Used to upload bitstreams to the FPGA
0x8004000	USB-to-SPI	this repo

The dapboot bootloader (at https://github.com/Lichee-Pi/dapboot) is used to flash other applications on the MCU, like the one in this repository. If the USER key is pressed when the board is powered, dapboot will start in DFU mode, allowing you to flash anything at address 0x8002000. Otherwise, if the button is not pressed, it will boot whatever is flashed at address 0x8002000.

The Makefile in this repository will install a patched version of the USB-to-JTAG application, which will allow you to boot the application at 0x8004000 by pressing the USER key during operation.

Prerequisites

• ARM TOOLCHAIN

  For Ubuntu users :

  sudo apt-get install gcc-arm-eabi
  

  Optionally build from source :

  https://developer.arm.com/tools-and-software/open-source-software/developer-tools/gnu-toolchain/gnu-rm
  

Installation

• git clone --recursive https://github.com/jg-fossh/gd32usb2spi.git

• cd gd32usb2spi/libopencm3/

• If using arm-elf toolchain (uncommon)

  PREFIX=arm-elf make

else run

make

• Go up a directory cd ../
• Run make to build the firmware.
• Hold the "USER" key pressed on the Tang Premier board and connect it to your PC over USB. It should get pop up as device "1209:db42".
• Run make flash to flash the patched USB-to-JTAG firmware as well as this USB-to-SPI.
• The device will now reconnect as device "0547:1002" (USB-to-JTAG).
• Press the "USER" key again to start the USB-to-SPI firmware

Usage

• Connect the Tang Premier board to USB without holding the "USER" key pressed
• Once the USB-to-JTAG device shows up, press the "USER" key to switch to USB-to-SPI mode

This USB-to-SPI firmware shows up as a CDC ACM serial device. The RTS signal controls the select line of SPI. Each byte sent to the ACM device will be sent over the MOSI line, and the response from MISO will appear on the ACM device.