// this is a OBD service project.

// hardware
// |--usart		data print
// |--led		alert-light
// |--beep		alert-voice
// |--key		restart
// |
// |--can		connect to vehicle
// |--wifi		data transmition
// |
// |--sd_card	data storage
// |--flash		app installation
// |--sram		running app