koendv/at32f405-uf2boot

Bootloader for Artery AT32F405 with QSPI flash

at32f405 uf2 boot

This is a uf2 bootloader for the Artery at32f405 arm processor with the application program on external flash.

This is work in progress.

Comparison

Compared to internal flash, external flash allows bigger programs at lower cost.

The bootloader has two functions:

• upload programs to external flash
• run programs from external flash

To upload programs to external flash, the bootloader presents itself as a usb disk drive. Files copied to the disk drive are written to flash.

To run programs from external flash, a read from main memory is translated to a read from external flash. This is called eXecute In Place (XIP). Processor cache memory is used to reduce the number of reads.

Processor internal flash:

• fast
• small (256kbyte)
• expensive

External flash:

• slower
• bigger (16mbyte)
• cheaper

Use

This is a uf2 bootloader for the Artery at32f405 arm processor with Winbond W25Q128JV 16mbyte qspi external flash and high-speed usb.

Connect the at32f405 high-speed usb to a pc. Double-click the reset button to enter device firmware update (DFU). The bootloader appears as a usb flash drive. The usb flash drive contains the file CURRENT.UF2. Two actions are defined: reading and writing.

• Copy the file CURRENT.UF2 to your pc to read qspi flash data.
• Copy firmware in uf2 format to CURRENT.UF2 to write firmware to qspi flash. The board reboots when flashing is complete.

In the linker script of the application, change the load address:

MEMORY
{
    ROM (rx) : ORIGIN = 0x90000000, LENGTH =  16M /* 16MB flash */
    RAM (rw) : ORIGIN = 0x20000000, LENGTH =  96k /* 96K sram */
}

Use objcopy and uf2-utils to convert between binary formats:

# extract binary from elf
arm-none-eabi-objcopy -O binary rtthread.elf rtthread.bin
# uf2 family id 0xf35c900d load address 0x90000000
bin2uf2 -f 0xf35c900d -o rtthread.uf2 0x90000000 rtthread.bin
# flash
cp rtthread.uf2 /media/koen/CherryUF2/CURRENT.UF2

Installation

The uf2 bootloader for the external flash is installed in the internal flash.

Install the bootloader using a debugger, or using dfu-util. To install using dfu-util:

• connect the board to usb
• push reset and boot0 buttons
• wait one second
• release the reset button
• wait one second
• release the boot0 button

At this point, the at32f405 ought to be in DFU mode:

$ lsusb
...
Bus 003 Device 012: ID 2e3c:df11 Artery-Tech DFU in FS Mode

With the firmware cherryuf2_at32f405rcu7_qspi_hs.bin in your current directory, execute the following command:

dfu-util -a 0 -d 2e3c:df11 --dfuse-address 0x08000000 -D cherryuf2_at32f405rcu7_qspi_hs.bin
...
Erase   	[=========================] 100%        23692 bytes
Erase    done.
Download	[=========================] 100%        23692 bytes
Download done.
File downloaded successfully

Push the reset button twice in quick succession. The uf2 bootloader usb disk appears.

Linux users: If dfu-util does not see the at32, execute dfu-util as root with sudo or set up udev-rules:

# Artery AT32 DFU
# Copy this file to /etc/udev/rules.d/99-at32.rules and run: sudo udevadm control -R
SUBSYSTEMS=="usb", ATTRS{idVendor}=="2e3c", ATTRS{idProduct}=="df11", TAG+="uaccess", MODE="0664", GROUP="plugdev"

Windows users: If dfu-util does not see the at32, download zadig, install the WinUSB driver and run dfu-util again.

Building

To build the bootloader:

cd src
git clone https://github.com/koendv/at32f405-uf2boot
cd  at32f405-uf2boot/ports/ArteryTek/at32f402_405
make BOARD=at32f405rcu7_qspi_hs clean
make BOARD=at32f405rcu7_qspi_hs all

The binaries are in the directory .build:

$ ls ~/src/at32f405-uf2boot/ports/ArteryTek/at32f402_405/.build/at32f405rcu7_qspi_hs
cherryuf2_at32f405rcu7_qspi_hs.bin
cherryuf2_at32f405rcu7_qspi_hs.elf
cherryuf2_at32f405rcu7_qspi_hs.elf.map
cherryuf2_at32f405rcu7_qspi_hs.hex

There are many possible pinouts to connect a qspi flash to a processor. The source files assume the pinout of this board.

Your board may use different pins to connect the qspi flash. To adapt the code to your board:

• in AT32 Work Bench, configure at least clocks, usb and qspi
• in AT32 Work Bench, click "Generate Code"
• put wk_system_clock_config() and wk_qspi1_init() from AT32F405RCT7_WorkBench/project/src/at32f402_405_wk_config.c in the file at32f405-uf2boot/ports/ArteryTek/at32f402_405/boards/at32f405rcu7_qspi_hs/wk_config.c

Console is on the serial port, pin A9. Output in dfu mode:

dfu
[SFUD]Found a Winbond flash chip. Size is 16777216 bytes.
[SFUD]qspi1 flash device initialized successfully.

Output when booting the app:

app

 \ | /
- RT -     Thread Operating System
 / | \     5.2.0 build Jul 14 2024 14:02:50
 2006 - 2024 Copyright by RT-Thread team

The bootloader has been compiled with xpack-arm-none-eabi-gcc-12.3.1-1.2 toolchain.

Sources

Notes about the source files.

The software defines two ways to enter the bootloader:

• double-clicking the reset button
• pushing the "user" button when the system boots

For more detailed output, uncomment SFUD_DEBUG_MODE in sfud_cfg.h

The bootloader has been tested with a Winbond W25Q128JV flash chip. If using a different flash chip:

• flash sector size and sector count is defined in board.h
• flash chips are defined in sfud_flash_def.h.
• the qspi read command is in qspi1_xip.c.

The AT_START_F405 board uses EN25QH128A-104H flash. If the EN25QH128A-104H flash chip is not recognized, add a line to SFUD_FLASH_CHIP_TABLE in sfud_flash_def.h:

{"EN25QH128A", SFUD_MF_ID_EON, 0x70, 0x18, 16L*1024L*1024L, SFUD_WM_PAGE_256B, 4096, 0x20}, \

The bootloader combines CherryUF2 and SFUD. Differences with upstream CherryUF2:

• at32f405rcu7_qspi_hs: board definition
• sfud: add Serial Flash Universal Driver
• tinyuf2: update to allow UF2 files bigger than 4mb (ghostfat.c)
• CherryUSB: SystemCoreClock type change (usb_dc_dwc2.c)
• at32 sdk: install latest qspi drivers to allow "auto input sampling phase correction" (at32f402_405_qspi.c)