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Instruction Set 2017-09-15T18:15:05+00:00

The Nextion Instruction Set

These are the set of commands that Nextion can use.
They are categorized into only a few categories

  1. General Rules and Practices … <goto>
  2. Assignment Statements … <goto>
  3. Operational Commands … <goto>
  4. GUI Designing Commands … <goto>
  5. Color Code Constants … <goto>
  6. System Variables … <goto>
  7. Format of Nextion Return Data … <goto>

1 – General Rules and Practices

No. General Rule or Practice
1 All instructions over serial: are terminated with three bytes of 0xFF 0xFF 0xFF
ie: decimal: 255  or  hex: 0xFF or  ansichar: ÿ  or binary: 11111111
ie  byte ndt[3] = {255,255,255}; write(ndt,3);  or print(“\xFF\xFF\xFF”);  or  print(“ÿÿÿ”)
2 All instructions and parameters are in ASCII
3 All instructions are in lowercase letters
4 Blocks of code and enclosed within braces { } can not be sent over serial
this means if, for, and while commands can not be used over serial
5 A space char 0x20 is used to separate command from parameters.
6 There are no spaces in parameters unless specifically stated
7 Nextion uses integer math and does not have real or floating support.
8 Assignment are non-complex evaluating fully when reaching value after operator.
9 Comparison evaluation is non-complex.  Use nesting when and as required.
10 Instructions over serial are processed on receiving termination (see 1.1)
11 Character escaping is limited to 0x0D by using two text chars \r
12 Nextion does not support order of operations.  sys0=3+(8*4) is invalid.
13 16-bit 565 Colors are in decimal from 0 to 65535 (see 5.Note)
14 Text values must be encapsulated with double quotes: ie “Hello”
15 Items within specific to Enhanced Models are noted with *K*
16 Transparent Data Mode (used by addt and wept commands)

  1. MCU sending to Nextion
    1. MCU sends command. ie: wept 30,20ÿÿÿ or addt 1,0,320ÿÿÿ
    2. Nextion requires ~5ms to prepare for transparent mode data transfer
    3. Nextion sends “Ready” 0xFE 0xFF 0xFF 0xFF Return Data (see 7.30)
    4. MCU can now send specified quantity (20) of raw bytes to Nextion
    5. Nextion receives raw bytes from MCU until specified quantity (20) is received
    6. Nextion sends “Finished” 0xFD 0xFF 0xFF 0xFF Return Data (see 7.29)
    7. MCU and Nextion can proceed to next command

Note: Nextion will remain waiting at step 5 until every byte of specified quantity is received.
– During this time Nextion can not execute any other commands, and may indeed hang if the MCU fails to deliver the number of bytes as specified by the command parameter.
– data quantity limited by serial buffer (all commands+terminations + data < 1024)

17 Only component attributes in green and non readonly system variables can be assigned new values at runtime.  All others are readonly at runtime.

2 – Assignment Statements

No. Data Type Operator Description/Example  (see 1.8 and 1.17)
1 Text = Assignment.  Right side will be evaluated with result placed in left side.  Component .txt-maxl needs to be large enough to hold result.
t0.txt=”Hello”
2 Text += Text Addition.  Will concatenate left side with right side with result placed left side.  ie t0.txt+=”Hello” is equivalent to t0.txt=t0.txt+”Hello”.
t0.txt=”-“+t0.txt becomes t0.txt=t0.txt+”-“.
Use temp variable to prepend.  va0.txt=t0.txt  t0.txt=”-“+va0.txt
t0.txt+=” World” // append ” World” to t0.txt
//When contents of t0.txt is “Hello” becomes “Hello World”
3 Text -= Text Subtraction.  Will remove right side (a specified numeric amount of characters to remove) from end of left side and result placed in left side.
t0.txt-=4 or t0.txt=t0.txt-4 // remove last 4 chars from t0.txt
4 Text \ Escape Character.
Supported is \r  hex 0x0D. (see 1.11)
t0.txt=”\r”
5 Text == Boolean Equality.  Evaluate left side to right side.
If both left and right sides are the same creates a true condition
if(t0.txt==va0.txt)
6 Text != Boolean Inequality.  Evaluate left side to right side.
If both left and right sides are different creates a true condition
if(t0.txt!=va0.txt)
7 Numeric = Assignment.  Right side of equation will be evaluated and result placed in left side. If more than one operator on right side, full evaluation and assignment will occur at each operator.
n0.val=bauds // places bauds value in n0.val component
8 Numeric += Numeric Addition. Adds value of left side and right side with result placed in left side.  n0.val+=4 is equivalent to n0.val=n0.val+4
n0.val+=va0.val
9 Numeric -= Numeric Subtraction. Subtracts right side from left side with result placed in left side.  n0.val-=4 is equivalent to n0.val=n0.val-4
n0.val-=60 // decreases value of n0.val by 60
10 Numeric *= Numeric Multiplication.  Multiplies left side with right side with product result placed in left side.  n0.val*=2 is equivalent of n0.val=n0.val*2
n0.val*=2
11 Numeric /= Numeric Division. Equates division of numerator (left side) and divisor (right side) and places integer quotient in left side.  60000/20001=2
n0.val/=60
12 Numeric %= Numeric Modulo.  Equates division of numerator (left side) and divisor (right side) and places integer remainder in left side.  60000/20001=19998
n0.val%=60
13 Numeric << Logical Bit Shift Left. Moves all bits specified number to the left.
All bits shifted above 15 are lost and undefined bits become 0
n0.val=n0.val<<4
0 0 0 0.0 0 1 1.1 1 0 0.0 0 0 1
0 0 1 1.1 1 0 0.0 0 0 1.       
0 0 1 1.1 1 0 0.0 0 0 1.0 0 0 0
14 Numeric >> Logical Bit Shift Right. Moves all bits specified number to the right.
All bits shifted below 0 are lost and undefined bits become 0
n0.val=n0.val>>4
0 0 0 0.0 0 1 1.1 1 0 0.0 0 0 1
             0 0 0 0.0 0 1 1.1 1 0 0
0 0 0 0.0 0 0 0.0 0 1 1.1 1 0 0
15 Numeric & Logical Bitwise AND. Compares all bits left side to all bits right side(mask)
Result is a bit of 1 where both left and right bits were 1
n0.val=n0.val&35381
0 1 0 1.1 0 1 1.0 0 1 0.0 1 0 1    n0.val of 23333
1 0 0 0.1 0 1 0.0 0 1 1.0 1 0 1   mask of 35381
0 0 0 0.1 0 1 0.0 0 1 0.0 1 0 1   result is 2597
16 Numeric | Logical Bitwise OR. Compares all bits left side to all bits right side
Result is a bit of 1 where either left or right bits were 1
n0.val=n0.val|35381
0 1 0 1.1 0 1 1.0 0 1 0.0 1 0 1    n0.val of 65519
1 0 0 0.1 0 1 0.0 0 1 1.0 1 0 1   constant 35381
1 1 0 1.1 0 1 1.0 0 1 1.0 1 0 1   result is 56117
17 Numeric == Boolean Equality.  Evaluate left side to right side.
If both left and right sides are the same creates a true condition
if(n0.val==va0.val)
18 Numeric != Boolean Inequality.  Evaluate left side to right side.
If both left and right sides are different creates a true condition
if(n0.val!=va0.val)
19 Numeric < Boolean Less than. Evaluate left side to right side.
If left side is less than right side creates a true condition
while(n0.val<va0.val)
20 Numeric <= Boolean Less than or Equal.  Evaluate left side to right side.
If left side is less than or equal to right side creates a true condition
while(n0.val<=va0.val)
21 Numeric > Boolean Greater than.  Evaluate left side to right side.
If left side is greater than right side creates a true condition
while(n0.val>va0.val)
22 Numeric >= Boolean Greater than or Equal.  Evaluate left side to right side.
If left side is greater than or equal to right side creates a true condition
while(n0.val>=va0.val)
23 Code {   } Code Block begins with open brace { on line by itself
Code Block ends with closing brace } beginning a new line
see if (see 3.25) while (see 3.26) and for (see 3.27)
24 Code (   ) Condition enclosure begins with open parenthesis (
and ends with closing parenthesis ) at end of line
see if (see 3.25) while (see 3.26) and for (see 3.27)
25 Code . Period Separator.  Separates Page, Component and Attributes
Also used with page index and component array. (see 2.26)
page1.va0.val or p0.pic
26 Code [   ] Array[index].  As shown in Keyboard source there are 2 arrays
1 is the component array b which takes component .id as index
The other is the page array p which takes page id  as index
Also needs to be used with caution and mindful purpose
Reference to a component without specified Attribute can
create for long and potentially frustrating debug sessions
p[pageindex].b[component.id].attribute // global scope
b[component.id].attribute // local scope on current page

3 – Operational Commands

No. Name Param Count Description and Usage/Parameters/Examples
1 page 1 Change page to page specified.  Unloads old page to load specified page.
Nextion loads page 0 by default on power on.
usage: page <pid>
<pid> is either the page index number, or pagename
page 0  // Change page to indexed page 0
page main // Change page to the page named main
2 ref 1 Refresh component (auto-refresh when attribute changes since v0.38)
– if component is obstructed (stacking), ref brings component to top.
usage: ref <cid>
<cid> is component’s .id or .objname attribute of component to refresh
– when <cid> is 0 (page component) refreshes all on the current page.
ref t0 // Refreshes the component with .objname of t0
ref 3  // Refreshes the component with .id of 3
ref 0  // Refreshes all components on the current page (same as ref 255)
3 click 2 Trigger the specified components Touch Press/Release Event
usage: click <cid>,<event>
<cid> is component’s .id or .objname attribute of component to refresh
<event> is 1 to trigger Press Event, 0 to trigger Release Events
click b0,1 // Trigger Touch Press Event of component with .objname b0
click 4,0 // Trigger Touch Release Event of component with .id 4
4 ref_stop 0 Stops default waveform refreshing (will not refresh when data point added)
– waveform refreshing will resume with ref_star (see 3.5)
usage: ref_stop
ref_stop // stop refreshing the waveform on each data point added
5 ref_star 0 Resume default waveform refreshing (refresh on data point add)
– used to resume waveform refreshing stopped by ref_stop (see 3.4)
usage: ref_start
ref_star // resume default refreshing, refresh on each data point added
6 get 1 Send attribute/constant over serial (0x70/0x71 Return Data)
usage: get <attribute>
<attribute> is either numeric value, .txt contents, or constant
get t0.txt // sends text contents of t0.txt in 0x70 Return Data format
get “123” // sends text constant “123” in 0x70 Return Data format
get n0.val // sends numeric value of n0.val in 0x71 Return Data format
get 123 // sends numeric constant 123 in 0x71 Return Data format
7 sendme 0 Sends number of currently loaded page over serial (0x66 Return Data)
– number of currently loaded page is stored in system variable dp
– used in a page’s initialize event will auto-send as page loads
usage: sendme
sendme // sends the value of dp in 0x66 Return Data Format
8 cov 3 Convert variable from numeric type to text, or text to numeric type
– text must be text ASCII representation of an integer value.
– source and destination types must not be of the same type
– when length is fixed and value is less, leading zeros will be added
ie: src numeric value of 123 with length 4, result is dest text “0123”
– when value is larger than length, .txt truncated to most significant digits
ie: src numeric value of 23425 with length 4 result is dest text “2342”
usage: cov <src>,<dest>,<length>
<src> is text attribute (or numeric attribute when <dest> is text)
<dest> is numeric attribute (or text attribute when <src> is numeric)
<length> will determine if leading zeros added to conversion to text
cov h0.val,t0.txt,0 // convert value of h0 into t0.txt without leading zeros
cov t0.txt,h0.val,0 // convert integer in t0.txt into h0.val <length> ignored.
cov h0.val,t0.txt,4 // convert value of h0 into t0.txt with exactly 4 digits
Invalid: cov h0.val,va0.val,0  or cov t0.txt,va0.txt,0 // src & dest same type.
9 touch_j 0 Recalibrate the Nextion device’s touch sensor
– presents 4 points on screen for user to touch, saves, and then reboots.
– typically not required as device is calibrated at factory
– sensor can be effected by changes of conditions in environment
usage: touch_j
touch_j // trigger the recalibration of touch sensor
10 substr 4 Extract character or characters from contents of a Text attribute
usage: substr <src>,<dest>,<start>,<count>
<src> is text attribute where text will be extracted from
<dest> is text attribute to where extracted text will be placed
<start> is start position for extraction (0 is first char, 1 second)
<count> is the number of characters to extract
substr va0.txt,t0.txt,0,5 // extract first 5 chars from va0.txt, put into t0.txt
11 vis 2 Hide or Show component on current page
– show will refresh component and bring it to the forefront layer
– hide will remove component visually, touch events will be disabled
– use layering with mindful purpose, can cause ripping and flickering.
– use with caution and mindful purpose, may lead to difficult debug session
usage: vis <comp><state>
<comp> is either .objname or .id of component on current page,
– valid .id is 0 – page, 1 to 250 if component exists, and 255 for all
<state> is either 0 to hide, or 1 to show.
vis b0,0 // hide component with .objname b0
vis b0,1 // show component with .objname b0, refresh on front layer
vis 1,0 // hide component with .id 1
vis 1,1 // show component with .id 1, refresh on front layer
vis 255,0 // hides all components on the current page
12 tsw 2 Enable or disable touch events for component on current page
– by default, all components are enabled unless disabled by tsw
– use with caution and mindful purpose, may lead to difficult debug session
usage: tsw <comp><state>
<comp> is either .objname or .id of component on current page,
– valid .id is 0 – page, 1 to 250 if component exists, and 255 for all
<state> is either 0 to disable, or 1 to enable.
tsw b0,0 // disable Touch Press/Release events for component b0
tsw b0,1 // enable Touch Press/Release events for component b0
tsw 1,0 // disable Touch Press/Release events for component with id 1
tsw 1,1 // enable Touch Press/Release events for component with id 1
tsw 255,0 // disable all Touch Press/Release events on current page
13 com_stop 0 Stop execution of instructions received from Serial
– Serial will continue to receive and store in buffer.
– execution of instructions from Serial will resume with com_star (see 3.14)
– using com_stop and com_star may cause a buffer overflow condition.
– Refer to device datasheet for buffer size and command queue size
usage: com_stop
com_stop // stops execution of instructions from Serial
14 com_star 0 Resume execution of instructions received from Serial
– used to resume an execution stop caused by com_stop (see 3.13)
– when com_star received, all instructions in buffer will be executed
– using com_stop and com_star may cause a buffer overflow condition.
– Refer to device datasheet for buffer size and command queue size
usage: com_star
com_star // resume execution of instruction from Serial
15 randset 2 Set the Random Generator Range for use with rand (see 6.14)
– range will persist until changed or Nextion rebooted
– set range to desired range before using rand
– power on default range is -2147483648 to 2147483647, runtime range is user definable.
usage: randset <min>,<max>
<min> is value is -2147483648 to 2147483647
<max> is value greater than min and less than 2147483647
randset 1,100 //set current random generator range from 1 to 100
randset 0,65535 //set current random generator range from 0 to 65535
16 code_c 0 Clear the commands queued in command buffer without execution
usage: code_c
code_c // Clears the command buffer without execution
17 print 1 Send raw formatted data over Serial to MCU
– print/printh does not use Nextion Return Data, user must handle MCU side
– qty of data may be limited by serial buffer (all data < 1024)
– numeric value sent in 4 byte 32-bit little endian order
value = byte1+byte2*256+byte3*65536+byte4*16777216
– text content sent is sent 1 ASCII byte per character, without null byte.
usage: print <attr>
<attr> is either component attribute, variable or Constant
print t0.txt // return 1 byte per char of t0.txt without null byte ending.
print j0.val // return  4 bytes for j0.val in little endian order
print “123” // return 3 bytes for text “123”  0x31 0x32 0x33
print 123 // return 4 bytes for value 123  0x7B 0x00 0x00 0x00
18 printh 1 to
many
Send raw byte or multiple raw bytes over Serial to MCU
– printh is one of the few commands that parameter uses space char 0x20
– when more than one byte is being sent a space separates each byte
– byte is represented by 2 of (ASCII char of hexadecimal value per nibble)
– qty may be limited by serial buffer (all data < 1024)
– print/printh does not use Nextion Return Data, user must handle MCU side
usage: printh <hexhex>[<space><hexhex][…<space><hexhex]
<hexhex> is hexadecimal value of each nibble.  0x34 as 34
<space> is a space char 0x20, used to separate each <hexhex> pair
printh 0d // send single byte: value 13 hex: 0x0d
printh 0d 0a // send two bytes:   value 13,10  hex: 0x0d0x0a
19 add 3 Add single value to Waveform Channel
– waveform channel data range is min 0, max 255
– 1 pixel column is used per data value added
– y placement is if value < s0.h then s0.y+s0.h-value, otherwise s0.y
usage: add <waveform>,<channel>,<value>
<waveform> is the .id of the waveform component
<channel> is the channel the data will be added to
<value> is ASCII text of data value, or numeric value
– valid: va0.val or sys0 or j0.val or 10
add 1,0,30 // add value 30 to Channel 0 of Waveform with .id 1
add 2,1,h0.val // add h0.val to Channel 1 of Waveform with .id 2
20 addt 3 Add specified number of bytes to Waveform Channel over Serial from MCU
– waveform channel data range is min 0, max 255
– 1 pixel column is used per data value added.
– addt uses Transparent Data Mode (see 1.16)
– waveform will not refresh until Transparent Data Mode completes.
– qty limited by serial buffer (all commands+terminations + data < 1024)
– also refer to add command (see 6.19)
usage: add <waveform>,<channel>,<qty>
<waveform> is the .id of the waveform component
<channel> is the channel the data will be added to
<qty> is the number of byte values to add to <channel>
addt 2,0,20 // adds 20 bytes to Channel 0 Waveform with .id 2 from serial
// byte of data is not ASCII text of byte value, but raw byte of data.
21 cle 3 Clear waveform channel data
usage: cle <waveform>,<channel>
<waveform> is the .id of the waveform component
<channel> is the channel to clear
<channel> must be a valid channel:  < waveform.ch or 255
0 if .ch 1, 1 if .ch 2, 2 if .ch 3, 3 if .ch=4 and 255 (all channels)
cle 1,0 // clear channel 0 data from waveform with .id 1
cle 2,255 // clear all channels from waveform with .id 2
22 rest 0 Resets the Nextion Device
usage: rest
rest // immediate reset of Nextion device – reboot.
23 doevents 0 Force immediate screen refresh and receive serial bytes to buffer
– useful inside exclusive code block for visual refresh (see 3.26 and 3.27)
usage: doevents
doevents // allows refresh and serial to receive during code block
24 strlen 2 Computes the length of string in <txt> and puts value in <len>
usage: strlen <txt>,<len>
<txt> must be a string attribute ie: t0.txt, va0.txt
<len> must be numeric  ie: n0.val, sys0, va0.val
strlen t0.txt,n0.val // assigns n0.val with length of t0.txt content
24a btlen 2 Computes number of bytes string in <txt> uses and puts value in <len>
usage: btlen <txt>,<len>
<txt> must be a string attribute ie: t0.txt, va0.txt
<len> must be numeric  ie: n0.val, sys0, va0.val
btlen t0.txt,n0.val // assigns n0.val with number of bytes t0.txt occupies
25 if Block Conditionally execute code block if boolean condition is met
– execute commands within block { } if (condition) is met.
– nested conditions () is not allowed.  invalid: ((h0.val+3)>0)
– block opening brace { must be on line by itself
– no space between block close brace } and else. valid: }else invalid: } else
– Text comparison supports ==, !=
– Numerical comparison supports >, <, ==, !=, >=, <=
– nested “if” and “else if” supported.
usage: if condition block [else if condition block] [else block]
– (condition) is a simple non-complex boolean comparison evaluation
valid:  (j0.val>75)  invalid: (j0.val+1>75) invalid: (j0.val<now.val+60)
if(t0.txt==”123456″)
{
page 1
}if(n0.val==123)
{
b0.txt=”stop”
}else
{
b0.txt=”start”
}if(rtc==1)
{
t0.txt=”Jan”
}else if(rtc1==2)
{
t0.txt=”Feb”
}else if(rtc1==3)
{
t0.txt=”Mar”
}else
{
t0.txt=”etc”
}
26 while Block Continually executes code block until boolean condition is no longer met
– tests boolean condition and execute commands within block { } if condition was met and continues to re-execute block until condition is not met.
– nested conditions () is not allowed.  invalid: ((h0.val+3)>0)
– block opening brace { must be on line by itself
– Text comparison supports ==, !=
– Numerical comparison supports >, <, ==, !=, >=, <=
– block runs exclusively until completion unless doevents used (see 3.23)
usage: while condition block
– (condition) is a simple non-complex boolean comparison evaluation
valid:  (j0.val>75)  invalid: (j0.val+1>75)
// increment n0.val as lon as n0.val < 100.  result: b0.val=100
// will not visually see n0.val increment, refresh when while-loop completes
while(n0.val<100)
{
n0.val++
}//increment n0.val as long as n0.val < 100. result: n0.val=100
// will visually see n0.val increment, refresh each evaluation of while-loop
while(n0.val<100)
{
n0.val++
doevents
}
27 for Block Iterate execution of code block as long as boolean condition is met
– executes init_assignment, then tests boolean condition and executes
commands within block { } if boolean condition is met, when iteration of
block execution completes step_assignment is executed.  Continues to
iterate block and step_assignment until boolean condition is not met.
– nested conditions () is not allowed.  invalid: ((h0.val+3)>0)
– block opening brace { must be on line by itself
– Text comparison supports ==, !=
– Numerical comparison supports >, <, ==, !=, >=, <=
– block runs exclusively until completion unless doevents used (see 3.23)
usage: for(init_assignment;condition;step_assignment) block
– init_assignment and step_assignment are simple non-complex statement
valid: n0.val=4, sys2++, n0.val=sys2*4+3 invalid:  n0.val=3+(sys2*4)-1
– (condition) is a simple non-complex boolean comparison evaluation
valid:  (j0.val>75)  invalid: (j0.val+1>75)
// iterate n0.val by 1’s as long as n0.val<100. result: n0.val=100
// will not visually see n0val increment until for-loop completes
for(n0.val=0;n0.val<100;n0.val++)
{
}//iterate n0.val by 2’s as long as n0.val<100. result: n0.val=100
// will visually see n0.val increment when doevents processed
for(n0.val=0;n0.val<100;n0.val+=2)
{
doevents
}
28
*K*
wepo 2 Store value/string to EEPROM
– EEPROM valid address range is from 0 to 1023 (1K EEPROM)
– numeric value length: is 4 bytes, -2147483648 to 2147483647
– numeric data type signed long integer, stored in little endian order.
val[addr+3]*16777216+val[addr+2]*65536+val[addr+1]*256+val[addr]
– string content length: .txt content is .txt-maxl +1, or constant length +1
usage: wepo <attr>,<addr>
<attr> is variable or constant
<addr> is storage starting address in EEPROM
wepo t0.txt,10 // writes t0.txt contents in addresses 10 to 10+t0.txt-maxl
wepo “abcd”,10 // write constant “abcd” in addresses 10 to 14
wepo 11,10 // write constant 11 in addresses 10 to 13
wepo n0.val,10 // write value n0.val in addresses 10 to 13
29
*K*
repo 2 Read value from EEPROM
– EEPROM valid address range is from 0 to 1023 (1K EEPROM)
– numeric value length: is 4 bytes, -2147483648 to 2147483647
– numeric data type signed long integer, stored in little endian order.
val[addr+3]*16777216+val[addr+2]*65536+val[addr+1]*256+val[addr]
– string content length: .txt content is lesser of .txt-maxl or until null reached.
usage: repo <attr>,<addr>
<attr> is variable or constant
<addr> is storage starting address in EEPROM
repo t0.txt,10 // reads qty .txt-maxl chars (or until null) from 10 into t0.txt
repo n0.val,10 // reads 4 bytes from address 10 to 13 into n0.val
30
*K*
wept 2 Store specified number of bytes to EEPROM over Serial from MCU
– EEPROM valid address range is from 0 to 1023 (1K EEPROM)
– wept uses Transparent Data Mode (see 1.16)
– qty limited by serial buffer (all commands+terminations + data < 1024)
usage: wept <addr>,<qty>
<addr> is storage starting address in EEPROM
<qty> is the number of bytes to store
wept 30,20 // writes 20 bytes into EEPROM addresses 30 to 49 from serial
// byte of data is not ASCII text of byte value, but raw byte of data.
31
*K*
rept 2 Read specified number of bytes from EEPROM over Serial to MCU
– EEPROM valid address range is from 0 to 1023 (1K EEPROM)
usage: rept <attr>,<addr>
<addr> is storage starting address in EEPROM
<qty> is the number of bytes to read
rept 30,20 // sends 20 bytes from EEPROM addresses 30 to 49 to serial
// byte of data is not ASCII text of byte value, but raw byte of data.
32
*K*
cfgpio 3 Configure Nextion GPIO
usage: cfgpio <io><mode><comp>
<io> is the number of the extended I/O pin.
– Valid values in PWM output mode: 4 to 7,  all other modes 0 to 7.
<mode> is the working mode of pin selected by <io>.
– Valid values:  0-pull up input, 1-input binding, 2-push pull output,
3-PWM output, 4-open drain output.
<comp> component .objname or .id when <mode> is 1 (otherwise use 0)
– in binding mode, cfgpio needs to be declared after every refresh of page to reconnect to Touch event, best to put cfgpio in page pre-initialization event
cfgpio 0,0,0 // configures io0 as a pull-up input.  Read as n0.val=pio0.
cfgpio 1,2,0 // configures io1 as a push-pull output, write as pio1=1
cfgpio 2,1, b0 // configures io2 as binding input with current page b0.
// binding triggers b0 Press on falling edge and b0 Release on rising edge
For PWM mode, set duty cycle before cfgpio: ie: pwm4=20 for 20% duty.
cfgpio 4,3,0 // configures io4 as PWM output.  pwmf=933 to change Hz.
// changing pwmf changes frequency of all configured PWM io4 to io7

4 – GUI Designing Commands

No. Name Param
Count
Description and Usage/Parameters/Examples
1 cls 1 Clear the screen and fill the entire screen with specified color
usage: cls <color>
<color> is either decimal 565 Color Value or Color Constant
cls BLUE // Clear the screen and fill with color BLUE
cls 1024 // Clear the screen and fill with color 1024
2 pic 3 Display a Resource Picture at specified coordinate
usage: pic <x>,<y>,<picid>
<x> is the x coordinate of upper left corner where picture should be drawn
<y> is the y coordinate of upper left corner where picture should be drawn
<picid> is the number of the Resource Picture in the HMI design
pic 10,20,0  // Display Resource Picture #0 with upper left corner at (10,20)
pic 40,50,1  // Display Resource Picture #1 with upper left corner at (40,50)
3 picq 5 Crop Picture area from Resource Picture using defined area
– replaces defined area with content from the same area of Resource Picture
– Resource Picture should be full screen-size or area might be undefined
usage: picq <x>,<y>,<w>,<h>,<picid>
<x> is the x coordinate of upper left corner of defined crop area
<y> is the y coordinate of upper left corner of defined crop area
<w> is the width of the defined crop area
<h> is the height of the defined crop area
<picid> is the number of the Resource Picture in the HMI design
picq 20,50,30,20,0
// crops area 30×20, from (20,50) to (49,69), from Resource Picture 0
4 xpic 7 Advanced Crop Picture
crop area from source Resource Picture render at destination coordinate
usage: xpic <destx>,<desty>,<w>,<h>,<srcx>,<srcy>,<picid>
<destx> is the x coordinate of destination upper left corner
<desty> is the y coordinate of destination upper left corner
<w> is the width of the defined crop area
<h> is the height of the defined crop area
<srcx> is the x coordinate of upper left corner of defined crop area
<srcy> is the y coordinate of upper left corner of defined crop area
<picid> is the number of the Resource Picture in the HMI design
xpic 20,50,30,20,15,15,0 // crops area 30×20, from (20,50) to (49,69),
// from Resource Picture 0 and renders it with upper left corner at (15,15)
5 xstr 11 Prints text on the Nextion device using defined area for text rendering
usage: xstr <x>,<y>,<w>,<h>,<font>,<pco>,<bco>,<xcen>,<ycen>,<sta>,<text>
<x> is the x coordinate of upper left corner of defined text area
<y> is the y coordinate of upper left corner of defined text area
<w> is the width of the defined text area
<h> is the height of the defined text area
<font> is the number of the Resource Font
<pco> is the foreground color of text (Color Constant or 565 color value)
<bco> is a) background color of text, or b) picid if <sta> is set to 0 or 2
<xcen> is the Horizontal Alignment (0 – left, 1 – centered, 2 – right)
<ycen> is the Vertical Alignment  (0 – top/upper, 1 – center, 3 – bottom/lower)
<sta> is background Fill (0 – crop image, 1 – solid color, 2 – image, 3 – none)
<text> is the string content (constant or .txt attribute), ie “China”, or va0.txt
xstr 10,10,100,30,1,WHITE,GREEN,1,1,1,va0.txt
// use are 100×30 from (10,10) to (109,39) to print contents of va0.txt using
// Font Resource 1 rendering Green letters on White background with both
// horizontal and vertical centering and sta set as solid-color.
6 fill 5 Fill a defined area with specified color
usage: fill <x>,<y>,<w>,<h>,<color>
<x> is the x coordinate of upper left corner of defined fill area
<y> is the y coordinate of upper left corner of defined fill area
<w> is the width of the defined fill area
<h> is the height of the defined fill area
<color> is fill color, either decimal 565 Color Value or Color Constant
fill 20,20,150,50,1024
// fills area 150×50 from (20,20) to (169,69) with 565 Color 1024.
7 line 5 Draw a line from point to point with specified color
usage: line <x1>,<y1>,<x2>,<y2>,<color>
<x1> is the x coordinate of the starting point of the line to be drawn
<y1> is the y coordinate of the starting point of the line to be drawn
<x2> is the x coordinate of the ending point of the line to be drawn
<y2> is the y coordinate of the ending point of the line to be drawn
<color> is line color, either decimal 565 Color Value or Color Constant
line 20,30,170,200,BLUE // draws line in BLUE from (20,30) to (170,200)
8 draw 5 Draw a hollow rectangle around specified area with specified color
usage: draw <x1>,<y1>,<x2>,<y2>,<color>
<x1> is the x coordinate of the upper left corner of rectangle area
<y1> is the y coordinate of the upper left corner of rectangle area
<x2> is the x coordinate of the lower right corner of rectangle area
<y2> is the y coordinate of the lower right corner of rectangle area
<color> is line color, either decimal 565 Color Value or Color Constant
draw 10,10,70,70,GREEN // draw a Green rectangle around (10,10) to (79,79)
// effectively four lines from (x1,y1) to (x2,y1) to (x2,y2) to (x1,y2) to (x1,y1)
9 cir 4 Draw a hollow circle with specified radius and specified color
usage: cir <x>,<y>,<radius>,<color>
<x> is the x coordinate of the center point for the circle
<y> is the y coordinate of the center point for the circle
<radius> is the radius in pixels
<color> is line color, either decimal 565 Color Value or Color Constant
cir 100,100,30,RED // renders a hollow Red circle with circle center at (100,100),
// a 30 pixel radius, a 61 pixel diameter, within boundary (70,70) to (130,130).
10 cirs 4 Draw a filled circle with specified radius and specified color
usage: cirs <x>,<y>,<radius>,<color>
<x> is the x coordinate of the center point for the circle
<y> is the y coordinate of the center point for the circle
<radius> is the radius in pixels
<color> is fill color, either decimal 565 Color Value or Color Constant
cir 100,100,30,RED // renders a filled Red circle with center at (100,100),
// a 30 pixel radius, a 61 pixel diameter, within boundary (70,70) to (130,130).

5 – Color Code Constants

No. Constant 565 Color Value  Indicator Color
1  BLACK 0  Black
2  BLUE 31  Blue
3  BROWN 48192  Brown
4  GREEN 2016  Green
5  YELLOW 65504  Yellow
6  RED 63488  Red
7  GRAY 33840  Gray
8  WHITE 65535  White
Note: 16-bit 565 Colors are in decimal values from 0 to 65535
24-bit RGB  11011000   11011000   11011000
16-bit 565   11011          110110        11011

6 – System Variables

No. Name Meaning Example/Description
1 dp Current
Page ID
dp=1, n0.val=dp
read: Contains the current page displayed as per the HMI design
write: change page to value specified (same effect as page command)
min 0, max # of highest existing page in the user’s HMI design.
2 dim
dims
Nextion
Backlight
dim=32, dims=100
Sets the backlight level in percent
min 0, max 100, default 100 or user defined
Note: dim=32 will set the current backlight level to 32%.
using dims=32 will set the current backlight level to 32% and save this to be new power on default backlight level, persisting until changed.
3 baud
bauds
Nextion
Baud Rate
baud=9600, bauds=9600
Sets the Nextion Baud rate in bits-per-second
min 2400, max 115200, default 9600 or user defined
Valid values are: 2400, 4800, 9600, 19200, 38400, 57600, and 115200.
Note: baud=38400 will set the current baud rate to 38400
using bauds=38400 will set the current baud rate to 38400 and save this to be new power on default baud rate, persisting until changed.
Note: on rare occasions bauds has become lost.  It is recommended to specify bauds=9600 in the first page’s Preinitialization Event of HMI.
4 spax
spay
Font
Spacing
spax=2, spay=2
Globally sets the default rendering space:
horizontally between font characters with spax additional pixels and
vertically between rows (if multi-lined) with spay additional pixels.
min 0, max 65535, default 0
Note: Components now have their own individual .spax/.spay attributes that are now used to determine spacing for the individual component.
5 thc Touch
Draw Brush
Color
thc=RED, thc=1024
Sets the Touch Drawing brush color
min 0, max 65535, default 0
Valid choices are either color constants or the decimal 565 color value.
6 thdra Touch
Drawing
thdra=1 (on), thdra=0 (off)
Turns the internal drawing function on or off.
min 0, max 1, default 0
When the drawing function is on, Nextion will follow touch dragging with the current brush color (as determined by the thc variable).
7 ussp Sleep on
No Serial
ussp=30
Sets internal No-serial-then-sleep timer to specified value in seconds
min 3, max 65535, default 0  (max: 18 hours 12 minutes 15 seconds)
Nextion will auto-enter sleep mode if and when this timer expires.
Note: ussp=0 is an invalid value, meaning once ussp is set, it will persist and can not be unset unless through reboot or reset.
8 thsp Sleep on
No Touch
thsp=30
Sets internal No-touch-then-sleep timer to specified value in seconds
min 3, max 65535, default 0  (max: 18 hours 12 minutes 15 seconds)
Nextion will auto-enter sleep mode if and when this timer expires.
Note: thsp=0 is an invalid value, meaning once thsp is set, it will persist and can not be unset unless through reboot or reset.
9 thup Auto Wake
on Touch
thup=0 (do not wake), thup=1 (wake on touch)
Sets if Nextion should auto-wake from sleep when touch press occurs.
min 0, max 1, default 0
When value is 1 and Nextion is in sleep mode, the first touch will only trigger the auto wake mode and not trigger a Touch Event.
thup has no influence on sendxy, sendxy will operate independently.
10 sendxy RealTime
Touch
Coordinates
sendxy=1 (start sending)  sendxy=0 (stop sending)
Sets if Nextion should send 0x67 and 0x68 Return Data
min 0, max 1, default 0
– Less accurate closer to edges, and more accurate closer to center.
Note: expecting exact pixel (0,0) or (799,479) is simply not achievable.
11 delay Delay delay=100
Creates a halt in Nextion code execution for specified time in ms
min 0, max 4294967295
As delay is interpreted, a total halt is avoided. Incoming serial data is received and stored in buffer but not be processed until delay ends.
delay=-1 is  max.  49 days 17 hours 2 minutes 47.295 seconds.
12 sleep Sleep sleep=1 (Enter sleep mode) or sleep=0 (Exit sleep mode)
Sets Nextion mode between sleep and awake.
min 0, max 1, default 0
When exiting sleep mode, the Nextion device will auto refresh the page
(as determined by the value in the wup variable) and reset the backlight brightness (as determined by the value in the dim variable).
13 bkcmd Pass / Fail
Return Data
bkcmd=3
Sets the level of Return Data on commands processed over Serial.
min 0, max 3, default 2
– Level 0 is Off – no pass/fail will be returned
– Level 1 is OnSuccess,  only when last serial command successful.
– Level 2 is OnFailure, only when last serial command failed
– Level 3 is Always, returns 0x00 to 0x24 result of serial command.
Result is only sent after serial command/task has been completed, as such this provides an invaluable status for debugging and branching.
14 rand Random
Value
n0.val=rand
Readonly. Value returned by rand is random every time it is referred to.
default range is 0 to 4294967295
range of rand is user customizable using the randset command
range as set with randset will persist until reboot or reset
15 sys0
sys1
sys2
Numeric
System
Variables
sys0=10 sys1=40 sys2=60 n0.val=sys2
System Variables are global in nature with no need to define or create.
They can be read or written from any page.  32-bit unsigned integers.
min value of 0, max value of 4294967295
Suggested uses of sys variables include
– as temporary variables in complex calculations
– as parameters to pass to click function or pass between pages.
16 wup Wake Up
Page
wup=2, n0.val=wup
Sets which page Nextion loads when exiting sleep mode
min is 0, max is # of last page in HMI, default 255
When wup=255 Nextion refreshes current page
wup can be set even when Nextion is in sleep mode
17
*K*
rtc0
rtc1
rtc2
rtc3
rtc4
rtc5
rtc6
RTC rtc0=2017, rtc1=8, rtc2=28,
rtc3=16, rtc4=50, rtc5=36, n0.val=rtc6
Nextion RTC:
rtc0 is year 2000 to 2099, rtc1 is month 1 to 12, rtc2 is day 1 to 31,
rtc3 is hour 0 to 23, rtc4 is minute 0 to 59, rtc5 is second 0 to 59.
rtc6 is dayofweek 0 to 6 (Sunday=0, Saturday=6)
rtc6 is readonly and calculated by RTC when date is valid.
18
*K*
pio0
pio1
pio2
pio3
pio4
pio5
pio6
pio7
GPIO pio3=1, pio3=0, n0.val=pio3
Default mode when power on: pull up input mode
Internal pull up resistor: 50K
GPIO is digital.  Value of 0 or 1 only.
– refer to cfgpio command for setting GPIO mode
read if in input mode, write if in output mode
19
*K*
pwm4
pwm5
pwm6
pwm7
PWM Duty
Cycle
 pwm4=25
Value in percentage.  min 0, max 100, default 50.
– refer to cfgpio command for setting GPIO mode
20
*K*
pwmf PWM
Frequency
 pwmf=933
Value is in Hz.  min value 1 Hz, max value 65535 Hz. default 1000 Hz
All PWM output is unified to only one Frequency, no independent individual settings are allowed.
– refer to cfgpio command for setting GPIO mode

7 – Format of Nextion Return Data

Return Codes dependent on bkcmd value being greater than 0
No. Byte bkcmd len Meaning Format/Description
1 0x00 2,3 4 Invalid Instruction 0x00 0xFF 0xFF 0xFF
Returned when instruction sent by user has failed
2 0x01 1,3 4 Instruction Successful 0x01 0xFF 0xFF 0xFF
Returned when instruction sent by user was successful
3 0x02 2,3 4 Invalid Component ID 0x02 0xFF 0xFF 0xFF
Returned when invalid Component ID or name was used
4 0x03 2,3 4 Invalid Page ID 0x03 0xFF 0xFF 0xFF
Returned when invalid Page ID or name was used
5 0x04 2,3 4 Invalid Picture ID 0x04 0xFF 0xFF 0xFF
Returned when invalid Picture ID was used
6 0x05 2,3 4 Invalid Font ID 0x05 0xFF 0xFF 0xFF
Returned when invalid Font ID was used
7 0x11 2,3 4 Invalid Baud rate Setting 0x11 0xFF 0xFF 0xFF
Returned when invalid Baud rate was used
8 0x12 2,3 4 Invalid Waveform ID or Channel # 0x12 0xFF 0xFF 0xFF
Returned when invalid Waveform ID or Channel # was used
9 0x1A 2,3 4 Invalid Variable name or attribute 0x1A 0xFF 0xFF 0xFF
Returned when invalid Variable name or invalid attribute was used
10 0x1B 2,3 4 Invalid Variable Operation 0x1B 0xFF 0xFF 0xFF
Returned when Operation of Variable is invalid. ie: Text assignment t0.txt=abc or t0.txt=23, Numeric assignment j0.val=”50″ or j0.val=abc
11 0x1C 2,3 4 Assignment failed to assign 0x1C 0xFF 0xFF 0xFF
Returned when attribute assignment failed to assign
12
*K*
0x1D 2,3 4 EEPROM Operation failed 0x1D 0xFF 0xFF 0xFF
Returned when an EEPROM Operation has failed
13 0x1E 2,3 4 Invalid Quantity of Parameters 0x1E 0xFF 0xFF 0xFF
Returned when the number of instruction parameters is invalid
14 0x1F 2,3 4 IO Operation failed 0x1F 0xFF 0xFF 0xFF
Returned when an IO operation has failed
15 0x20 2,3 4 Escape Character Invalid 0x20 0xFF 0xFF 0xFF
Returned when an unsupported escape character is used
16 0x23 2,3 4 Variable name too long 0x23 0xFF 0xFF 0xFF
Returned when variable name is too long. Max length is 29 characters: 14 for page + “.” + 14 for component.
17 0x24 2,3 4 Serial Buffer Overflow 0x24 0xFF 0xFF 0xFF
Returned when a Serial Buffer overflow occurs

Return Codes not affected by bkcmd value, valid in all cases
No. Byte length Meaning Format/Description
18 0x00 6 Nextion Startup 0x00 0x00 0x00 0xFF 0xFF 0xFF
Returned when Nextion has started or reset
19 0x65 7 Touch Event 0x65 0x00 0x01 0x01 0xFF 0xFF 0xFF
Returned when Touch occurs and component’s
corresponding Send Component ID is checked
in the users HMI design.
0x00 is page number, 0x01 is component ID,
0x01 is event (0x01 Press and 0x00 Release)
data: Page 0, Component 1, Pressed
20 0x66 5 Current Page Number 0x66 0x01 0xFF 0xFF 0xFF
Returned when the sendme command is used.
0x01 is current page number
data: page 1
21 0x67 9 Touch Coordinate (awake) 0x67 0x00 0x7A 0x00 0x1E 0x01 0xFF 0xFF 0xFF
Returned when sendxy=1 and not in sleep mode
0x00 0x7A is x coordinate in big endian order,
0x00 0x1E is y coordinate in big endian order,
0x01 is event (0x01 Press and 0x00 Release)
(0x00*256+0x71,0x00*256+0x1E)
data: (122,30) Pressed
22 0x68 9 Touch Coordinate (sleep) 0x68 0x00 0x7A 0x00 0x1E 0x01 0xFF 0xFF 0xFF
Returned when sendxy=1 and in sleep mode
0x00 0x7A is x coordinate in big endian order,
0x00 0x1E is y coordinate in big endian order,
0x01 is event (0x01 Press and 0x00 Release)
(0x00*256+0x71,0x00*256+0x1E)
data: (122,30) Pressed
23 0x70 Varied String Data Enclosed 0x70 0x61 0x62 0x31 0x32 0x33 0xFF 0xFF 0xFF
Returned when using get command for a string.
Each byte is converted to char.
data: ab123
24 0x71 8 Numeric Data Enclosed 0x71 0x01 0x02 0x03 0x04 0xFF 0xFF 0xFF
Returned when get command to return a number
4 byte 32-bit value in little endian order.
(0x01+0x02*256+0x03*65536+0x04*16777216)
data: 67305985
25 0x86 4 Auto Entered Sleep Mode 0x86 0xFF 0xFF 0xFF
Returned when Nextion enters sleep automatically
Using sleep=1 will not return an 0x86
26 0x87 4 Auto Wake from Sleep 0x87 0xFF 0xFF 0xFF
Returned when Nextion leaves sleep automatically
Using sleep=0 will not return an 0x87
27 0x88 4 Nextion Ready 0x88 0xFF 0xFF 0xFF
Returned when Nextion has powered up
and is now initialized successfully
28 0x89 4 Start microSD Upgrade 0x89 0xFF 0xFF 0xFF
Returned when power on detects inserted microSD
and begins Upgrade by microSD process
29 0xFD 4 Transparent Data Finished 0xFD 0xFF 0xFF 0xFF
Returned when all requested bytes of Transparent
Data mode have been received, and is now leaving transparent data mode (see 1.16)
30 0xFE 4 Transparent Data Ready 0xFE 0xFF 0xFF 0xFF
Returned when requesting Transparent Data
mode, and device is now ready to begin receiving
the specified quantity of data (see 1.16)