GD32F107RC Bootloader TFTP
This bootloader will install your application by means of the TFTP protocol. There is no need to change your application code. Per default DHCP is used for obtaining the ip-address.
The bootloader is active during reset of the board:
- Or when the
KEY_BOOTLOADER_TFTP_GPIO_PINxis pressed. Which is defined in filelib-gd32/include/board/gd32f107r.h. - Or when
bkp_data_read(BKP_DATA_1) == 0xA5A5. This is set in your application by means of human readable UDP messages. See for more information: https://www.gd32-dmx.org/bootloader.html. There is also a sample Java UI application available for working with the UDP messages: https://github.com/vanvught/GD32F-Firmware-Update-UI
Otherwise the bootloader will directly jump to your application. With the snippet:
// 8. Call the reset handler
const uint32_t* reset_p = (uint32_t *)(FLASH_BASE + OFFSET_UIMAGE + 4);
asm volatile ("bx %0;" : : "r"(*reset_p));
The bootloader can be installed with the tools supplied by GigaDevice: http://www.gd32mcu.com/en/download/7?kw=GD32F1
The limitation for the firmware file to be uploaded is given by the RAM available. For example, the MCU on https://github.com/vanvught/GD32FxxxR-dev-board is the GD32F107RCT6. With the 96K RAM we have the firmware file size limit of 74K.
See also https://www.gd32-dmx.org/bootloader.html
File: spiflashinstall.h
# if defined (BOARD_GD32F107R)
# define OFFSET_UIMAGE 0x007000 // 28K
# define FIRMWARE_MAX_SIZE (74 * 1024) // 74K
The change to be made in your build configuration is in the file gd32f107rc_flash.ld.
/* Specify the memory areas */
MEMORY
{
FLASH (rx) : ORIGIN = 0x08007000, LENGTH = 74K
RAM (xrw) : ORIGIN = 0x20000000, LENGTH = 96K
}
The FLASH ORIGIN must match the OFFSET_UIMAGE from the bootloader file spiflashinstall.h
The code for the bootloader is a fork from https://github.com/vanvught/rpidmx512. In order to reduce the memory footprint, some functions are not available.