Nextion Instruction Set

Note:

1. The instruction is end with three bytes "0xff 0xff 0xff"

2. All the instrucitons and parametners are in ASCII

3. All the instrucitons are in lowercase letters

Classification I: Operation Commands of Component and System

page: Refresh page

page pageid

pageid: Page ID or Page Name

• Example 1:

page 0         //Refresh page 0

• Example 2:

page main    //Refresh the page main

Remarks:

The device automatically refresh page 0 when power on.

---

ref: Refresh component

ref cmpID

cmpID: component ID or component name

• Example

ref t0   //refresh component t0
ref 1    // refresh component 1

Remarks:

1. The default loading mode is automatically load when you create and edit a component in Nextion Editor. If set it as manually load, you should use ref command to load the component. Or when the component is covered by the other components, you can use this command to refresh the covered component.

2. Component auto refresh when attribute changes only valid for those attributes in green bold font. The other attributes not in this format can only be refreshed and displayed by the command of ref.

3.When creating a component in Nextion editor, the default loading mode is auto loading. When the loading mode is set as manual loading, it requires to use ref to load. When the component is sheltered by GUI command mapping, or when the component is sheltered by other manual loading components, you can use ref to refresh the component.

---

click: Activate component's press/release event

click cmpID, event

cmpID: component ID or component name

event: 0 - release event; 1 - press event

• Example

click b0, 1   //activate press event of component b0
click 2, 0   //activate release event of component 2

Remark:

1, Use "click" command to activate press/release event of a component without touch the LCD.

ref_stop: Stop refreshing screen

• Example

ref_stop   // no parameters

Remarks:

1.If you do not want to see the whole waveform flow progress, rather, you want to view the whole waveform all at once, you can stop refreshing the screen and refresh it when all adopted points being passed through.

2.Once stop refreshing the screen, all other commands and responded attribute assign operations will still run normally, but the components on the screen will not auto-refresh, neither will any changes in component attributes be refreshed and displayed on the screen(the changes are valid). When the device receive the command ref_star, those changes will be immediately refreshed and displayed on the screen (on condition that the changes are made from the attributes in green bold font).

3.When stop refreshing the screen, ref command will still be executed. Besides, all GUI drawing instructions such as draw point, draw line will still be executed and any changes will be immediately displayed.

---

ref_star: Recover refreshing screen

ref_star: recover refreshing screen

• Example

ref_star   // no parameters

Remarks:

This command should be used after ref_stop command.

---

get: Get variable/constant value with format

get att

att: variable name

• Example 1

get t0.txt      //return t0's txt value

• Example 2

get j0.val    //return J0's val value

• Example 3

get "123"      //return constant string "123"

• Example 4

get 123      //return constant value: 123

Remarks:

1. When returned value is a string, the returned data is 0X70+ASCII code+0xff 0xff 0xff.

2. When returned value is numerical, returned data is 0X71+4 byte binary data+0xff 0xff 0xff. The data storage mode is little-endian mode (namely, low-order in front, and high-order at back).

3. The specific returning format of data, please refer to the table: Format of Device Return Data

---

sendme: send current pageID to UART

• Example:

sendme  //no parameters

Remarks:

If you want the page auto-send pageID every refresh, simply enter sendme in page initialize event.

---

cov: variable type conversion

cov att1,att2,lenth

att1: source variable

att2: target variable

lenth: length of the string(0 - automatic length, nonzero - fixed length)

• Example 1:

cov h0.val,t0.txt,0  //convert the value variable of slider h0 val into decimal string and assign the txt variable of t0, the length is automatic

• Example 2:

cov t0.txt,j0.val,0  //convert the string variable of t0 txt into value and assign the variable of slider h0 val, the length is automatic

Remarks:

1.lenth always represents the length of the string, when the value converts into string, it is the length of target variable; when the string converts into value, it is the length of source variable.

2. If the target variable and source variable are of the same type, the conversion failed.

---

touch_j: Touch calibration

touch_j:

• Example:

touch_j   //Enter touch calibration function, this command does not need parameter

Remarks:

All the devices have been calibrated before packing from the factory, this command is not needed under normal circumstances

---

substr: Extracts the characters from a string

substr att0,att1,star,lenth

att0: A string from which a substring is to be returned

att1: Returned substring

star: The position where to start the extraction. First character is at index 0

lenth: Specifies the length of the returned string

• Example:

 substr t0.txt,t1.txt,0,2  

Remarks:

All the devices have been calibrated before packing from the factory, this command is not needed under normal circumstances

---

vis: Hide/show component

vis obj,state

obj: component name or component ID

• Example 1:

vis b0,0   //hide component b0

• Example 2:

vis b0,1   //show component b0

• Example 3:

vis 1,0   //hide the component whose ID is 1

• Example 4:

vis 1,1   //show the component whose ID is 1

Remarks:

1.The first parameter 255 means all components in current page, for example: vis 255,0 (hide all components in current page); vis 255,1 (show all components in current page).

---

tsw: Enable/disable component touch function

tsw cmp,state

cmp: component name or component ID

state:(0=disable or 1=enable)

• Example 1:

tsw b0,0  //component b0 touch invalid

• Example 2:

tsw b0,1  //component b0 touch valid

• Example 3:

tsw 1,0  //component of ID 1 touch invalid

• Example 4:

tsw 1,1  //component of ID 1 touch valid

Remarks:

1.The first parameter 255 means all components in current page, for example: tsw 255, 0 (all components in current page touch invalid); tsw 255, 1 (all components in current page touch valid).

---

com_stop: Stop execute instructions from UART

• Example:

com_stop  //no parameters

Remarks:

This command is used for pausing the execution of serial port commands, but note that the device will continue receiving the commands and store them in the buffer. Until receiving "com_star" commands, the device will execute the rest commands that store in the buffer.

When using this command to pause the execution, please make sure whether the buffer size and the maximum capacity of command queue can store all the commands you need. You will find these two parameter in Nextion Hardware manual.

---

com_star: Execute instructions from UART

• Example:

com_star  //no parameters

Remarks:

After receiving this command, the device will execute all the commands that store in buffer and new commands form UART.

When using com_stop and com_start, please make sure whether the buffer size and the maximum capacity of command queue can store all the commands you need. You will find these two parameter in Nextion Hardware manual.

---

randset: Set random value range

randset minval,maxval

minval: minimum value

maxval: maximum value

• Example:

ranset 1,100  //set current value randomly generated from 1 to 100

Remarks:

1. You should use randset to set random value generated range beforehand. Without setting randset, the value range will be 0~4294967295 by default. Aftering setting randset, you will get a new random value within the preset range every time you run rand

2. The range set by randset keeps valid unless the device being reboot or reset.

---

code_c: Clear the buffer

• Example:

code_c   //no parameters

Remarks: Clear the commands that is stored in the buffer without execution.

---

print: Get variable variable/constant value without format

print att

att: variable name

• Example 1:

print t0.txt //returns the txt property value of component t0 in ASCII

• Example 2:

print j0.val //returns val’s property value of component j0 in 4-byte hexadecimal data

• Example 3:

print "123" //returns the ASCII of string "123":0x31 0x32 0x33

• Example 4:

print 123 //returns the 4-byte hexadecimal data of value "123":0x7B 0x00 0x00 0x00

Remarks:

1. When the variable obtained by using print command is string type, the device directly returns string ASCII; if it is numeric type (such as progress val property) , the device will directly return the variable’s 4-byte hexadecimal data, value is stored as little-endian mode (ie low level in the front, high level at the back ).

2. When use print command to obtain data, the device sends only the data content, no start identifier, nor end mark.

3.print command can match up printh command to add a piece of user-defined label in the front so as to tell the microcontroller which component this variable belongs to).

4. print command is very similar to get command, the only difference between them is get command returns data with initial identifier (0x70 or 0x71) and end mark (0xff 0xff 0xff), while print not.

---

printh: Send hexadecimal string

printh hex hex: the characters' hexadecimal string expression to be sent

• Example

printh d0 a0 //let device send these two bytes 0xd0 0xa0

Remarks:

1. print and printh commands are executed only in Nextion display, they will not be shown in the software simulator.

2. When using printh command to send data, the device sends specified characters only, no Start character, Space character or End character.

3. There must have one and only Space separated between each set of characters in the parameter, both upper case and lower case are supported in the hexadecimal string expression.

---

add: Add data to waveform component

add objid, ch, val

objid: Waveform component ID

ch: Waveform component channel number

val: value (maximum 255, minimum 0)

• Example 1

add 1, 0, 30  //add data 30 to channel 0 of the Waveform component which ID number is 1

• Example 2

add 1, 1, 50  //add data 50 to channel 1 of the Waveform component which ID number is 1

Remarks:

1.Waveform component only support 8-bit values, 0 minimum, 255 maximum.

2.Each page supports up to four Waveform components, each Waveform component supports up to four channels. It supports continuously pass through data, the component will auto-flow and display the value. It supports to change attributes during passing through data, such as change the background color or foreground color for each channel during the process.

---

addt: Add data to waveform component in volume

addt objid, ch, qty

objid: waveform component ID

ch: channel number of waveform component

qty: adopted point quantity of the data

• Example:

addt 1, 0, 100  //waveform component whose ID is 1 enter into data pass through mode, pass through adopted point quantity is 100

Remarks:

1.Waveform component only support 8-bit values, 0 minimum, 255 maximum. Single pass through is 1024 bits maximum.

2.After sending waveform data pass through command, it will take some time to get the device responded and started passing through values. This period takes about 5ms(it will take longer if there are other commands to be executed in the buffer zone before executing data pass through command). Following this period, it will send a data pass through ready data(0XFE+Terminator) to user, then it will start sending pass through data. The data being passed are only hexadecimal numbers. It recovers to command receiving state only after the device has adopted specified data.

3.Waveform will not refresh until specified data has been passed through completely.

---

cle: Clear data in waveform component

cle objid, ch

objid: waveform component ID (component name or variable is not supported); ch: channel

• Example:

cle 1, 0   //clear the data of waveform component ID=1, channel=0;
cle 1, 255   //clear all the data of waveform component ID=1 

Remarks: ch=255: all channels

rest: Reset Nextion device

rest

Example:

 rest    //no parameters  

---

doevents: Force refresh the screen immediately

doevents

Example:

 doevents //no parameters

while(n0.val<1024)
{
n0.val++
doevents    //the screen will keep refreshing during the loop
}

Remark: 1, In a long looping statement, you can use doevents to avoid the screen display like brick. 2, doevents usually work with "while" or "for" statement.

strlen: check length of a string

strlen att0, att1

att0: source string variable att1: return value, length of att0

Example:

 strlen t0.txt, n0.val  //assign length of t0.txt to n0.val

Remark:

1, att0 must be string, att1 must be numeric.

---

if: if statement

• Example 1: If to.txt equals to 123456, it will switch to page 1

if(t0.txt==”123456”)
{    
Page 1
}

• Example 2: Below codes can switch content of txt of button component b0 between start and stop in press event)

if(b0.txt==”start”
{    
  b0.txt==”stop”  
} else
{ 
  b0.txt==”start”  
}

• Example 3: Below codes can switch content of txt of button component b0 among 1, 2, 3 in press event)

if(b0.txt==”1”
{    
  b0.txt==”2”  
} else if (b0.txt==”2” )
{ 
  b0.txt==”3”  
}else
{ 
  b0.txt==”1”
}

Remarks:

1. Numerical variable supports operators: “>, <, ==, !=, >=, <=”

2. Character and String variable supports operators: “==, !=”

3. Nested “()” operator is not allowed. It does not support comparison operation, such as: if (j0.val + 1> 0).

4. Operator “()” must be paired.

5. Supports nested “if” and “else if” statement.

6.Complex expression, such as “if (j0.val+1>0)” is not supported

7.Download "if" HMI demo here: Demo

while: while statemet

Example:

//n0.val will auto-add to 100, in this process the screen will 
//not refresh the result until all the statements of this process 
//being completely executed.
while(n0.val<100)
{
n0.val++
}


//n0.val will auto-add to 100, in this process the screen will 
//keep refreshing and displaying the result of component n0.

while(n0.val<100)
{
n0.val++
doevents
}  

Remarks: 1, In the process of executing a while loop, the device will not show corresponding touch event, serial command will be received in buffer, but not executed until all the statements in the process has finished execution. Please be cautious when using this command, or it might be easily enter into endless loop. 2, It's recommended to use "doevents" command together. 3, refer to remark of "if" statement

for: for statemet

• Examples:

//n0.val will auto-add to 100, in this process the screen will
//not refresh the result until all the statements of this process 
//being completely executed.

for(n0.val=0; n0.val<100; n0.val++)
{
}

//n0.val will auto-add to 100, in this process the screen will
// keep refreshing and displaying the result of component n0 .

for(n0.val=0; n0.val<100; n0.val++)
{
doevents   
}

repo: read EEPROM - Enhanced Model Only

repo att, add

att: variable/constant

add: storage address in EEPROM

Example:

repo t0.txt,10 // read and assign value to t0.txt, read length is (t0.txt-mal)+1
repo n0.val,10      //read and assign value to n0.val, read length is 4 bytes

Remark:

1， read a string from EEPROM, read length is length of the string+1.

2, read a numeric value from EEPROM, read length is 4 bytes.

---

wepo: write EEPROM - Enhanced Model Only

wepo att,add

att: variable/constant

add: storage address in EEPROM

Example:

wepo t0.txt,10 // write value of t0.txt to EEPROM, start from address #10. storage size is (t0.txt-mal)+1 bytes
wepo "abcd",10   // write string "abcd" to EEPROM, start from address #10. storage size is 5 bytes
wepo 11,10  //write constant 11 to EEPROM, start from address #10. storage size 4 bytes  

Remark:

1, Storage address start from 0byte to 1023byte.

2, Storage size of a string is 1 byte + string length; storage size of a numeric constant is 4 bytes.

3, Supported numeric data type is long integer, from -2,147,483,648 to 2,147,483,647 [v035 supports 0 to 2,147,483,647 only]

---

wept: write data in hex to EEPROM through UART - Enhanced Model Only

wept add, length

add: start address in EEPROM

length: length of data

Example:

wept 30, 20 // write 20 bytes of hex data from UART to EERPOM, start address is 30 

Remark:

1, When wept instruction received, Nextion device will take around 5ms to initiate and send ready signal “0xFE 0xFF 0xFF 0xFF"

2, Before you send data from UART, you should wait until you get ready signal from Nextion device

3, wept can not be terminated.

---

rept: read data in hex from EEPROM to UART - Enhanced Model Only

rept add, lenght

add: start address in EEPROM

length: length of data

Example:

rept 30, 20 // read 20 bytes of hex data from EEPROM to UART, start address is 30 

---

cfgpio: configure GPIO - Enhanced Model Only

cfgpio id,state,cmp

id: I/O pin number

state: work state of the GPIO

  0 - pull up input mode
  1 - input binding mode
  2 - push pull output mode
  3 - PWM output mode
  4 - open drain output mode

cmp: binding component, available in work state 2

Example:

cfgpio 0, 0, 0    //Configure GPIO0 as pull up input mode, you can read the input status from system variable pio0, 
                       //such as: n0.val = pio0

cfgpio 1, 2, 0   //Configure GPIO1 as push pull output mode, you can control the output level 
                 //by system variable pio1, such as: pio1 = 1

cfgpio 2, 1, b0   //Configure GPIO2 as input binding mode, the binding component is button b0. 
                  //Falling edge of GPIO2 will trigger b0's button press event, rising edge of 
                  //GPIO2 will trigger bo's button release event.

cfgpio 4, 3, 0   //Configure GPIO4 as PWM output mode, you should use system variable pwm4 
                 //to set duty cycle before you use the instruction

Remark:

1, only GPIO4 to GPIO7 support PWM function

2, When configure a GPIO to input binding mode, only components in current page can be bind. It is recommended to put the instruction in the preinitialize event, because binding event wont not be triggered after page refreshing or switching.

---

Classification II: GUI Designing Command

Note: When you can’t realize some special GUI designing in Nextion Editor, you can use some GUI commands to make it happen. Generally, the controls in Nextion editor can satisfy your GUI designing demand.

cls: clear the screen

cls color

color: Decimal color value or color code

• Example 1:

cls 1024  //Refresh the screen with decimal 1024 color value

• Example 2:

cls RED  //Refresh the screen with the color of code RED (RED represents red color)

Both Decimal color value and Color code are supported in Nextion Editor

---

pic: display picutres

pic x, y, picid

x: x coordinate starting point;

y: y coordinate starting point;

picid: Picture ID;

• Example 1:

pic 10, 20, 0  //Display the picture (ID is 0) in resource file at the coordinate (10, 20)

• Example 2:

pic 40, 50, 1  //Display the picture (ID is 1) in resource file at the coordinate (40, 50)

---

picq: Crop picture

picq x, y, w, h, picid

x: x coordinate starting point;

y: y coordinate starting point;

w: area width;

h: area height;

picid: Picture ID;

• Example:

picq 20, 50, 30, 20, 0  
//Crop the area from starting coordinate (20, 50) , with a width 30×height 20 size, 
//in the picture 0 (the background picture must be full-screen) and display it on 
//the screen, and the display coordinate is the starting coordinate (20, 50).

Remarks:

This instruction requires that the background picture must be full-screen; otherwise, the image you crop is not the one you want. The crop image area and the display area is overlap on the screen.

---

xpic: Advanced crop picture

xpic x, y, w, h, x0, y0, picid

x: x coordinate starting point;

y: y coordinate starting point;

w: Region width;

h: Region height;

x0: crop picture starting point x coordinate;

y0: crop picture starting point y coordinate;

picid: Picture ID;

• Example:

picq 20, 50, 30, 20, 15, 15, 0  
//Crop the area from starting coordinate (15, 15) ,
//with a width 30 × height 20 size, in the picture 0 (the background 
//picture must be full-screen) and display it on the screen, and the display
//coordinate is the starting coordinate (20, 50).

---

xstr: Print string on the device

xstr x, y, w, h, fontid, fontcolor, backcolor, xcenter, ycenter, sta, string

x: x coordinate starting point;

y: y coordinate starting point;

w: area width;

h: area height;

fontid: Font ID;

fontcolor: Font color;

backcolor: Background color (when set sta as Crop Image or Image, backcolor means image ID );

xcenter: Horizontal alignment (0 is left-aligned, 1 is centered, 2 is right-aligned);

ycenter: Vertical alignment (0 is upper-aligned, 1 is centered, 2 is lower-aligned);

sta: Background fill(0-crop image;1-solid color;2-Image; 3-No backcolor, when set sta as Crop Image or Image, backcolor means image ID);

string: Character content;

• Example:

xstr 0, 0, 100, 30, 1, RED, BLACK, 1, 1, 1, "China"

• Explanation:

Use font 1, at the starting point coordinate(0,0), write"China" in an area that its width is 100, height is 30, the font color is RED, background color is BLACK, horizontal alignment is center, and vertical alignment is center too.

Remarks:

1.There is automatic word wrapping if characters exceeds the default set w. If there are remaining characters not written out when wrapped to h, they will be neglected.

2. For more information about color value, please refer to cls command.

---

fill x, y, w, h, color

Fill area

x: x coordinate starting point;

y: y coordinate starting point;

w: area width;

h: area height;

color: fill color;

• Example:

fill 0, 0, 100, 30, RED  //Fill color RED in the area of starting coordinate (0, 0) and width 100×height 30

Remarks:

For more information about color value, please refer to cls command.

---

line x, y, x2, y2, color

x: x coordinate starting point;

y: y coordinate starting point;

x2: x coordinate ending point;

y2: y coordinate ending point;

color: Line color;

• Example:

line 0, 0, 100, 100, RED  //Draw a line in color RED between the coordinate (0, 0) and the coordinate (100, 100)

Remarks:

For more information about color value, please refer to cls command.

---

draw x, y, x2, y2, color

x: x coordinate starting point;

y: y coordinate starting point;

x2: x coordinate ending point;

y2: y coordinate ending point;

color: Line color;

• Example:

draw 0, 0, 100, 100, RED    //Draw a rectangle, the top left coordinate is (0, 0) and bottom right corner is (100, 100), rectangle frame color is RED.

Remarks:

1. What is drawn by draw is hollow rectangle. Please directly use area fill instruction of fill if the filled rectangle needs filling. 2. For more information about color value, please refer to cls command.

---

cir x, y, r, color

cir x, y, r, color: draw a hollow circle

x: Coordinate x of the center of a circle

y: Coordinate y of the center of a circle

r: Radius

color: Line color;

• Example:

cir 100, 100, 30, RED    //Draw a hollow circle whose radius is 30 with the coordinate (100, 100) as the center of a circle, circle frame line is RED

Remarks: For more information about color value, please refer to cls command.

---

Nextion Editor supports decimal color value and color code using in all GUI designing commands, for more information, please refer to Color Code List.

cirs x, y, r, color

cirs x, y, r, color:draw a solid circle

x: circle center x coordinate

y: circle center y coordinate

r: Radius

color: Fill color;

• Example

cirs 100, 100, 30, RED    //Draw a solid circle whose radius is 30 with the coordinate (100, 100) as the center of a circle, circle color is RED

Remarks: For more information about color value, please refer to cls command.

---

Nextion HMI: System Variables List

Item	Name	Meaning	Instance/Remarks
1	dim	Current value of backlight brightness	1.dim=50 2.dim=dim+l0 3.dim=dim-l0 When you set dim=80, it means you have set the brightness as 80, but did not save it as default. Next time you power on the Nextion TFT, the brightness of backlight will keep its default setting.
2	dims	default backlight brightness when Nextion is powered on	1.dims=50 2.dims=dims+10 3.dims=dims-l0 When you set dims=80 to Nextion TFT, it means you have set the brightness as 80, and have saved it as default. Next time you power on the Nextion TFT, the brightness of backlight will be 80 by default.
3	baud	Current value of baud	1.baud=2400 2.baud=4800 3.baud=9600 4.baud=19200 5.baud=38400 6.baud=57600 7.baud=115200
4	bauds	Default value of baud when Nextion is powered on	1.bauds=9600 is the default baud of factory settings. 2.when you set bauds=115200 to Nextion, it means you have set the baud as 115200, and saved it as default. Next time you power the Nextion, the value of baud will be 115200 by default.
5	spax	Horizontal spacing of font display (default 0)	spax=2
6	spay	Vertical spacing of font display (default 0)	spay=2
7	thc	Brush color at touch drawing	l.thc=RED 2.thc=l024
8	thdra	Touch drawing function	thdra=0(C1ose) thdra=1(Open)
9	ussp	If no serial data, it will auto activate sleep time (unit: second, minimum 3, maximum 65,535, power-on default 0)	ussp=30(No serial data within 30 seconds, it auto will enter into sleep mode) ussp=0(invalid)
10	thsp	If no touch operation, it will auto enter into sleep time (unit: second, minimum 3, maximum 65,535, power-on default 0)	thsp=30(No touch operation within 30 seconds, it will auto enter into sleep mode) thsp=0(invalid)
11	thup	Touch in sleep mode will auto-awake switch (power-on default 0)	thup=0(Touch will not auto awake switch during sleep mode) thup=1(Touch will autom awake switch during sleep mode) Remarks: Whether thup be 0 or 1, whenever there is any touch operation in sleep mode, the device will send touch coordinates to the serial port.
12	sendxy	Close or open real-time sending touch coordinate function	sendxy=0(C1ose) sendxy=1(Open) Remarks: 1. When this function is open, the device will send touch coordinate through serial port when you touch the screen. 2. Please refer to the table: Format of Device Return Data to learn more about the format of sending the coordinate.
13	delay		Delay=100(Pause the device for l00ms) Remarks: When delay command is executed, the CPU of the device will not execute any commands, but will continue receiving serial port command and store them to buffer.
14	sleep		sleep=0 (Exit Sleep) sleep=l (Enter Sleep) Remarks: When the device wake up from sleep mode, the device will auto refresh the current page, and the backlight brightness will recover to the default brightness value. Two commands available for changing the brightness of backlight, dim and dims.
15	bkcmd	Data return of successful/failed execute serial command(2 by default)	bkcmd=0 (No return) bkcmd=l (Only return the successful data) bkcmd=2(Only return the failed data) bkcmd=3（Always return） Remarks: This setting only affects the serial command’s successful execution or fail execution’s data return. In Nextion Editor’s editing interface, when there is a command execution error, it will return error data; when the command being executed successfully, it will not return execution result data.
16	rand	random value	dim=rand (assign a random value to backlight brightness) n0.val=rand (assign a random value to variable of n0.val) Remarks: 1.Before use rand, you should use randset command to set random value generated range. If you do not set it, the default range will be 0~4294967295. Aftering setting randset, you will get a new random value within the preset range every time you run rand. 2. The range set by randset keeps valid unless the device being reboot or reset.
17	sys0 sys1 sys2	Numeric system variables	sys0=10 sys1=40 sys2=60 n.val=sys2 Remarks: ys0, sys1, sys2 are global variables, which do not required to define or create. You can use them in any page. Default value for these three variables are 0, they can be read and write, their value range are 0~4294967295. It's recommended to pass values through pages with they system variables.
18	rtc0 to rtc6	RTC variables (Enhanced Only)	rtc0, year; rtc1, month; rtc2, day; rtc3, hour; rtc4, min; rtc5, second; rtc6, week;
19	pio0 to pio7	GPIO variables (Enhanced Only)	Default mode when power on: pull up input mode Internal pull up resistor: 50K
20	pwm4 to pwm7	Duty cycle for the PWM GPIO (Enhanced Only)	min value = 0, max value = 100, default = 50;
21	pwmf	PWM frequency (Enhanced Only)	min value = 1Hz, max value = 65536 Hz, default = 1000Hz; All PWM output is unified to one frequency, no independent setting is allowed.
22	wup	Refresh certain page when wake up	wup=255 (default, refresh current page), wup=2 (refresh page 2 when wake up) Note: Nextion can execute wup even in sleep mode;

Nextion HMI: Color Code List

Code	Decimal System	Indicator Color
RED	63488	Red
BLUE	31	Blue
GRAY	33840	Gray
BLACK	0	Black
WHITE	65535	White
GREEN	2016	Green
BROWN	48192	Brown
YELLOW	65504	Yellow

Format of Device Return Data

Table 1: serial l instruction execution success or failure notification format

1.Only when the system variable bkcmd is not zero will return instruction execution succeed or fail data, bkcmd defaults to 0 after each power on, which means it does not return the result of instruction execution.

2.The code of the source file is not affected by bkcmd when software is under editing, the error data will be returned when there is an execution error, and the error data will not be returned when execute success.

3.The returned data is ended with three bytes of “0XFF 0XFF 0XFF”.

The first byte of returned data	Meaning	Format
0X00	Invalid instruction	0X00+End
		Return this data when receiving the invalid instruction sent by the user
0X01	Successful execution of instruction	0X01+End
		Return this data when the instruction sent by the user is successfully executed
0X02	Component ID invalid	0X02+End
		Return this data when the instruction from external device contains invalid component ID or invalid component name
0X03	Page ID invalid	0X03+End
		Return this data when the instruction sent by external device contains invalid page ID or invalid page name
0X04	Picture ID invalid	0X04+End
		Return this data when the instruction sent by the user contains invalid picture ID
0X05	Font ID invalid	0X05+End
		Return this data when the instruction sent by the user contains invalid font ID
0X11	Baud rate setting invalid	0X11+End
		The baud rate setting instruction sent by the user contains invalid baud rate parameter
		Baud rate supported by the device including:2400 4800 9600 19200 38400 57600 115200
0X12	Curve control ID number or channel number is invalid	0X12+End
		When users use the add commands to add data to curve, this data will be returned as curve control ID number or channel number is invalid
0X1A	Variable name invalid	0X1A+End
		Return this data when the serial port receives invalid variable name
		Note: control attribute is also called variable. For example, when you set the attribute of a control, it will return this data if the unavailable attribute name is input.
0X1B	Variable operation invalid	0X1B+End
		For example, when txt attribute of text component t0 is assigned, it should be written as t0.txt=“abc” It is wrong if you write t0.txt=abc.
		For another example, the val attribute of progress bar j0 should be numerical, so it should be written as j0.val=50; it will be wrong if you write j0.val=“50” or j0.val=abc.
0X1C	Failed to assign	0X1C+End Return this data when attribute failed to assign.
0X1D	Operate EEPROM failed	0X1D+End Return this data when operate EEPROM failed.
0X1E	Parameter quantity invalid	0X1E+End Return this data when the instruction parameter quantity input by user is wrong.
0X1F	IO operation failed	0X1F+End Return this data when operate IO failed.
0X20	Undefined escape characters	0X20+End Return this data when you use a undefined escape character.
0X23	Too long variable name	0X23+End Maximum allowed length of a variable is 29 characters.

Table 2: other data return format

1.The returned data is end with three bytes of “0XFF 0XFF 0XFF”.

2.The following data’s return does not be affected by bkcmd.

The first byte of returned data	Meaning	Format
0X65	Touch event return data	0X65+Page ID+Component ID+TouchEvent+End
		Return this data when the touch event created by the user is pressed.
		Definition of TouchEvent: Press Event 0x01, Release Event 0X00)
		Instance: 0X65 0X00 0X02 0X01 0XFF 0XFF 0XFF'
		Meaning: Page 0, Button 2, Press
0X66	Current page ID number returns	0X66+Page ID+End
		The device returns this data after receiving “sendme” instruction)
		Instance: 0X66 0X02 0XFF 0XFF 0XFF
		Meaning: Current page ID is 2
0X67	Touch coordinate data returns	0X67++ Coordinate X High-order+Coordinate X Low-order+Coordinate Y High-order+Coordinate Y Low-order+TouchEvent State+End
		When the system variable “sendxy” is 1, return this data at TouchEvent occurring
		Definition of TouchEvent: Press Event 0x01, Release Event 0X00
		Instance: 0X67 0X00 0X7A 0X00 0X1E 0X01 0XFF 0XFF 0XFF
		Meaning: Coordinate (122,30), Touch Event: Press
0X68	Touch Event in sleep mode	0X68++Coordinate X High-order+Coordinate X Low-order+Coordinate Y High-order+Coordinate Y Low-order+TouchEvent State+End
		When the device enters sleep mode, return this data at TouchEvent occurring
		Definition of TouchEvent: Press Event 0x01, Release Event 0X00
		Instance: 0X68 0X00 0X7A 0X00 0X1E 0X01 0XFF 0XFF 0XFF
		Meaning: Coordinate (122,30), Touch Event: Press
0X70	String variable data returns	0X70+Variable Content in ASCII code+End
		When the variable obtained through get command is string type, return this data
		Instance: 0X70 0X61 0X62 0X63 0XFF 0XFF 0XFF
		Meaning: Return the string data: “abc”
0X71	Numeric variable data returns	0X71+variable binary data(4 bytes little endian mode, low in front)+End
		When the variable obtained by get command is value, this data returns.
		Instance:0X71 0X66 0X00 0X00 0X00 0XFF 0XFF 0XFF
		Meaning:return value data:102
0X86	Device automatically enters into sleep mode	0X86+End Only when the device automatically enters into sleep mode will return this data. If execute serial command “sleep = 1” to enter into sleep mode, it will not return this data.
0X87	Device automatically wake up	0X87+End Only when the device automatically wake up will return this data. If execute serial command “sleep=0” to wake up, it will not return this data.
0X88	System successful start up	This data is sent after a successful power-on initialization on the device
0X89	Start SD card upgrade	This data is sent after the device power on and detect SD card, and then enter upgrade interface
0XFD	Data transparent transmit finished	0xFD+End
OXFE	Data transparent transmit ready	The device will enter into transparent transmission data initialization mode after receiving data transparent transmission instruction. Data will be sent once the initialization is completed, which means it has entered into data transparent transmission mode and start to transparent transmit data.

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