it is a bootloader of c8051f340. open it with keil. after download its HEX file into target board. connet target s UART0 with PC s COM , config COM port as 115200-8-n-1, use Xmode to transmit file. then power on target.

基于STM32的bootloader,应用Xmode协议。可远程升级应用程序APP(IAP)，无需直接连接芯片。-Based on the STM32 bootloader, use Xmodem protocol. You can remotely upgrade the application APP (IAP), without direct connection chip.