1. Get firmware information
Format:
	{"cmd":"firmware"}
Desc:
	Get the firmware version and vendor ID

2. Get version
Format:	
	{"cmd":"version"}
	
3. Get the UID of device
Format:	
	{"cmd":"serialno"}
	
4. Clear screen
Format:
	{"cmd":"clear-screen: left#top#width#height"}
	{"cmd":"clear-screen: 0#0#319#479"}
Desc:
	Clear the specified rectangle region with the backgroun color.
Parameters:
	left       : The starting column coordinate of the left-top of the rectangle,
	             It's in pixel, range from 0 - 319.
	top        : The starting row coordinate of the left-top of the rectangle,
	             It's in pixel, range from 0 - 479.
	width      : The width of the rectangle in pixel.
	height     : The height of the rectangle in pixel.
	
5. Show text in screen
Format:	
	{"cmd":"display-string: row#col#font size#text"}
	{"cmd":"display-string: 20#8#24#hello world,this is my test line213"}
Desc:
	Display a text string in the specified starting position of screen.
Parameters:
	row        : Display the starting row coordinate of the text,
	             It's in pixel, range from 0 - 319.
	column     : Display the starting column coordinate of the text,
	             It's in pixel, range from 0 - 479.
	font size  : There are 3 font sizes available in DQ11, they are 8, 16 or 24.
	text       : The text string to be displayed.
	
6. Set foreground color
Format:
	{"cmd":"foreground-color: #color"}
	"For Red Color" : {"cmd":"foreground-color: #F800"} 
Desc:
	Set the foreground color for screen.
Parameters:
	color : The format of color is 16-bits RGB(5-6-5).

7. Set background color
Format:
	{"cmd":"background-color: #color"}
	"For Red Color" : {"cmd":"background-color: #F800"}
Desc:
	Set the background color for screen.
Parameters:
	color : The format of color is 16-bits RGB(5-6-5).
	
8. Convert the text string to QR-code and show the QR.
Format:
	{"cmd":"display-qrcode: row#column#width#text string"}
        {"cmd":"display-qrcode: 10#10#100#text string"}
Desc:
	Convert text string to qr coding and show the QR in the specified region of screen.
Parameters:
	row        : The row coordinate of left-top of the square region for showing the QR.
	column     : The column coordinate of left-top of the square region for showing the QR.
	width      : The width of the square region for showing the QR.
	text-string: The text string that will be converted to QR.