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.

C8051F340的USB HID方式的BOOTLOADER，包含使用说明，固件代码（Keil uv3工程），上位机可执行文件.-C8051F340 USB HID mode BOOTLOADER, contains instructions for use, the firmware code (Keil uv3 engineering), host computer executable file.