nodemcu-firmware/docs/en/modules/node.md

node Module

The node module provides access to system-level features such as sleep, restart and various info and IDs.

node.bootreason()

Returns the boot reason code.

This is the raw code, not the new "reset info" code which was introduced in recent SDKs. Values are:

• 1: power-on
• 2: reset (software?)
• 3: hardware reset via reset pin
• 4: WDT reset (watchdog timeout)

####Syntax node.bootreason()

####Parameters nil

####Returns number:the boot reason code

####Example

rsn = node.bootreason()

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node.restart()

Restarts the chip.

####Syntax node.restart()

####Parameters nil

####Returns nil

####Example

node.restart();

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node.dsleep()

Enter deep sleep mode, wake up when timed out.

####Syntax node.dsleep(us, option)

Note: This function can only be used in the condition that esp8266 PIN32(RST) and PIN8(XPD_DCDC aka GPIO16) are connected together. Using sleep(0) will set no wake up timer, connect a GPIO to pin RST, the chip will wake up by a falling-edge on pin RST.
option=0, init data byte 108 is valuable;
option>0, init data byte 108 is valueless.
More details as follows:
0, RF_CAL or not after deep-sleep wake up, depends on init data byte 108.
1, RF_CAL after deep-sleep wake up, there will belarge current.
2, no RF_CAL after deep-sleep wake up, there will only be small current.
4, disable RF after deep-sleep wake up, just like modem sleep, there will be the smallest current.

####Parameters

• us: number(Integer) or nil, sleep time in micro second. If us = 0, it will sleep forever. If us = nil, will not set sleep time.

• option: number(Integer) or nil. If option = nil, it will use last alive setting as default option.

####Returns nil

####Example

--do nothing
node.dsleep()
--sleep μs
node.dsleep(1000000)
--set sleep option, then sleep μs
node.dsleep(1000000, 4)
--set sleep option only
node.dsleep(nil,4)

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node.info()

Returns NodeMCU version, chipid, flashid, flash size, flash mode, flash speed.

####Syntax node.info()

####Parameters nil

####Returns

• majorVer (number)
• minorVer (number)
• devVer (number)
• chipid (number)
• flashid (number)
• flashsize (number)
• flashmode (number)
• flashspeed (number)

####Example

    majorVer, minorVer, devVer, chipid, flashid, flashsize, flashmode, flashspeed = node.info()
    print("NodeMCU "..majorVer.."."..minorVer.."."..devVer)

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node.chipid()

Returns the ESP chip ID.

####Syntax node.chipid()

####Parameters nil

####Returns number:chip ID

####Example

    id = node.chipid();

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node.flashid()

Returns the flash chip ID.

####Syntax node.flashid()

####Parameters nil

####Returns number:flash ID

####Example

    flashid = node.flashid();

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node.heap()

Returns the current available heap size in bytes. Note that due to fragmentation, actual allocations of this size may not be possible.

####Syntax node.heap()

####Parameters nil

####Returns number: system heap size left in bytes

####Example

    heap_size = node.heap();

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node.key() --deprecated

Define action to take on button press (on the old devkit 0.9), button connected to GPIO 16.

This function is only available if the firmware was compiled with DEVKIT_VERSION_0_9 defined.

####Syntax node.key(type, function)

####Parameters

• type: type is either string "long" or "short". long: press the key for 3 seconds, short: press shortly(less than 3 seconds)
• function: user defined function which is called when key is pressed. If nil, remove the user defined function. Default function: long: change LED blinking rate, short: reset chip

####Returns nil

####Example

    node.key("long", function() print('hello world') end)

####See also

• node.led()

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node.led() --deprecated

Set the on/off time for the LED (on the old devkit 0.9), with the LED connected to GPIO16, multiplexed with node.key().

This function is only available if the firmware was compiled with DEVKIT_VERSION_0_9 defined.

####Syntax node.led(low, high)

####Parameters

• low: LED off time, LED keeps on when low=0. Unit: milliseconds, time resolution: 80~100ms
  
• high: LED on time. Unit: milliseconds, time resolution: 80~100ms

####Returns nil

####Example

    -- turn led on forever.
    node.led(0)

####See also

• node.key()

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node.input()

Submit a string to the Lua interpreter. Similar to pcall(loadstring(str)), but without the single-line limitation.

!!! note "Note:"

This function only has an effect when invoked from a callback. Using it directly on the console does not work.

####Syntax node.input(str)

####Parameters

• str: Lua chunk

####Returns nil

####Example

    sk:on("receive", function(conn, payload) node.input(payload) end)

####See also

• node.output()

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node.output()

Redirects the Lua interpreter output to a callback function. Optionally also prints it to the serial console.

!!! note "Note:"

Do not attempt to print() or otherwise induce the Lua interpreter to produce output from within the callback function. Doing so results in infinite recursion, and leads to a watchdog-triggered restart.

####Syntax node.output(output_fn, serial_debug)

####Parameters

• output_fn(str): a function accept every output as str, and can send the output to a socket (or maybe a file).
• serial_debug: 1 output also show in serial. 0: no serial output.

####Returns nil

####Example

    function tonet(str)
      sk:send(str)
    end
    node.output(tonet, 1)  -- serial also get the lua output.

    -- a simple telnet server
    s=net.createServer(net.TCP)
    s:listen(2323,function(c)
       con_std = c
       function s_output(str)
          if(con_std~=nil)
             then con_std:send(str)
          end
       end
       node.output(s_output, 0)   -- re-direct output to function s_ouput.
       c:on("receive",function(c,l)
          node.input(l)           -- works like pcall(loadstring(l)) but support multiple separate line
       end)
       c:on("disconnection",function(c)
          con_std = nil
          node.output(nil)        -- un-regist the redirect output function, output goes to serial
       end)
    end)

####See also

• node.input()

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node.readvdd33() --deprecated, moved to adc.readvdd33()

####See also

• adc.readvdd33()

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node.compile()

Compile a Lua text file into Lua bytecode, and save it as .lc file.

####Syntax node.compile(filename)

####Parameters

• filename: name of Lua text file

####Returns nil

####Example

  file.open("hello.lua","w+")
  file.writeline([[print("hello nodemcu")]])
  file.writeline([[print(node.heap())]])
  file.close()

  node.compile("hello.lua")
  dofile("hello.lua")
  dofile("hello.lc")

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node.setcpufreq()

Change the working CPU Frequency.

####Syntax node.setcpufreq(speed)

####Parameters

• speed: node.CPU80MHZ or node.CPU160MHZ

####Returns number:target CPU Frequency

####Example

    node.setcpufreq(node.CPU80MHZ)

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node.restore()

Restore system configuration to defaults. Erases all stored WiFi settings, and resets the "esp init data" to the defaults. This function is intended as a last-resort without having to reflash the ESP altogether.

This also uses the SDK function system_restore(), which doesn't document precisely what it erases/restores.

####Syntax node.restore()

####Parameters nil

####Returns nil

####Example

    node.restore()
    node.restart() -- ensure the restored settings take effect

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node.stripdebug()

Controls the amount of debug information kept during node.compile(), and allows removal of debug information from already compiled Lua code.

Only recommended for advanced users, the NodeMCU defaults are fine for almost all use cases.

####Syntax `node.stripdebug([level[, function]])``

####Parameters

• level:
  • 1: don't discard debug info
  • 2: discard Local and Upvalue debug info
  • 3: discard Local, Upvalue and line-number debug info
• function: a compiled function to be stripped per setfenv except 0 is not permitted.

If no arguments are given then the current default setting is returned. If function is omitted, this is the default setting for future compiles. The function argument uses the same rules as for setfenv().

Returns

If invoked without arguments, returns the current level settings. Otherwise, nil is returned.

####Example

node.stripdebug(3)
node.compile('bigstuff.lua')

####See also

• node.compile()

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