nodemcu-firmware/docs/modules/node.md

node Module

Since	Origin / Contributor	Maintainer	Source
2014-12-22	Zeroday	Zeroday	node.c

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

node.bootreason()

Returns the boot reason and extended reset info.

The first value returned 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)

The second value returned is the extended reset cause. Values are:

• 0, power-on
• 1, hardware watchdog reset
• 2, exception reset
• 3, software watchdog reset
• 4, software restart
• 5, wake from deep sleep
• 6, external reset

Or the internal reset code of the system can be returned as extended reset cause:

• 7: NO_MEAN no known reason
• 8: POWERON_RESET power on reset, this includes reset button connected to power-on reset
• 9:
• 10 SW_RESET software reset digital core caused by esp-idk firmware
• 11: OWDT_RESET legacy watch dog reset digital core
• 12: DEEPSLEEP_RESET Deep Sleep reset digital core
• 13: SDIO_RESET Reset by SLC module, reset digital core
• 14: TG0WDT_SYS_RESET Timer Group0 Watch dog reset digital core
• 15: TG1WDT_SYS_RESET Timer Group1 Watch dog reset digital core
• 16: RTCWDT_SYS_RESET RTC Watch dog Reset digital core
• 17: INTRUSION_RESET Instrusion tested to reset CPU
• 18: TGWDT_CPU_RESET Time Group reset CPU
• 19: SW_CPU_RESET Software reset (from node.restart() or lua PANIC)
• 20: RTCWDT_CPU_RESET RTC Watch dog Reset CPU
• 21: EXT_CPU_RESET for APP CPU, reseted by PRO CPU
• 22: RTCWDT_BROWN_OUT_RESET Reset when the vdd voltage is not stable
• 23: RTCWDT_RTC_RESET RTC Watch dog reset digital core and rtc module

In general, the extended reset cause supercedes the raw code. The raw code is kept for backwards compatibility only. For new applications it is highly recommended to use the extended reset cause instead.

In case of extended reset cause 3 (exception reset), additional values are returned containing the crash information. These are, in order, EXCCAUSE, EPC1, EPC2, EPC3, EXCVADDR, and DEPC.

In case of extended reset cause 19 (SW_CPU_RESET), an additional value is returned containing the number of consecutive Lua panics. If the reset was caused by a call to node.restart() this value is 0; after the first panic the value is 1; if a panic reoccurs the value increments upto 15.

Syntax

node.bootreason()

Parameters

none

Returns

rawcode, reason [, exccause, epc1, epc2, epc3, excvaddr, depc ]

Example

_, reset_reason = node.bootreason()
if reset_reason == 0 then print("Power UP!") end

node.chipid()

Returns the ESP chip ID.

Syntax

node.chipid()

Parameters

none

Returns

chip ID (string)

Note that due to the chip id being a much larger value on the ESP32, it is reported as a string now. E.g. "0x1818fe346a88".

node.compile()

Compiles a Lua text file into Lua bytecode, and saves it as .lc file.

Syntax

node.compile("file.lua")

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")

node.dsleep()

Enters deep sleep mode. When the processor wakes back up depends on the supplied options. Unlike light sleep, waking from deep sleep restarts the processor, therefore this API never returns. Wake up can be triggered by a time period, or when a GPIO (or GPIOs) change level, or when a touchpad event occurs. If multiple different wakeup sources are specified, the processor will wake when any of them occur. Use node.bootreason() to determine what caused the wakeup.

Only RTC GPIO pins can be used to trigger wake from deep sleep, and they should be configured as inputs prior to calling this API. On the ESP32, the RTC pins are GPIOs 0, 2, 4, 12-15, 25-27, and 32-39. An error will be raised if any of the specified pins are not RTC-capable. If multiple pins are specified and level=1 (which is the default), the wakeup will occur if any of the pins are high. If level=0 then the wakeup will only occur if all the specified pins are low.

For compatibility, a number parameter usecs can be supplied instead of an options table, which is equivalent to node.dsleep({us = usecs}).

Syntax

node.dsleep(usecs) or node.dsleep(options)

Parameters

• options, a table containing some of:
  • secs, a number of seconds to sleep. This permits longer sleep periods compared to using the us parameter.
  • us, a number of microseconds to sleep. If both secs and us are provided, the values are combined.
  • gpio, a single GPIO number or a list of GPIOs. These pins must all be RTC-capable otherwise an error is raised.
  • level. Whether to trigger when any of the GPIOs are high (level=1, which is the default if not specified), or when all the GPIOs are low (level=0).
  • isolate. A list of GPIOs to isolate. Isolating a GPIO disables input, output, pullup, pulldown, and enables hold feature for an RTC IO. Use this option if an RTC IO needs to be disconnected from internal circuits in deep sleep, to minimize leakage current.
  • pull, boolean, whether to keep powering previously-configured internal pullup/pulldown resistors. Default is false if not specified.
  • touch, boolean, whether to trigger wakeup from any previously-configured touchpads. Default is false if not specified.

If an empty options table is specified, ie no wakeup sources, then the chip will sleep forever with no way to wake it (except for power cycling or triggering the reset pin/button).

Returns

Does not return.

Example

-- sleep 10 seconds then reboot
node.dsleep({ secs = 10 })

-- sleep until 10 seconds have elapsed or either of GPIO 13 or 15 becomes high
node.dsleep({ secs = 10, gpio = { 13, 15 } })

-- Sleep forever until GPIO 13 is low, and keep its pullup powered
node.dsleep({ gpio = 13, level = 0, pull = true })

See also

• node.sleep()

node.flashid()

Returns the flash chip ID.

Syntax

node.flashid()

Parameters

none

Returns

flash ID (number)

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

none

Returns

system heap size left in bytes (number)

node.info()

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

Syntax

node.info()

Parameters

none

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)

node.input()

Submits 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()

node.key() --deprecated

Defines 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()

node.led() --deprecated

Sets 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()

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(function(str), serial_output)

Parameters

• output_fn(str) a function accept every output as str, and can send the output to a socket (or maybe a file). nil to unregister the previous function.
• serial_output 1 output also sent out the serial port. 0: no serial output. Defaults to 1 if not specified.

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)

-- disable all output completely
node.output(nil, 0)

See also

node.input()

node.osoutput()

Redirects the debugging output from the Espressif SDK to a callback function allowing it to be captured or processed in Lua.

####Syntax node.osoutput(function(str))

Parameters

• function(str) a function accepts debugging output as str, and can send the output to a socket (or maybe a file). nil to unregister the previous function.

Returns

Nothing

Example

function luaprint(str)
  print("lua space: "str)
end
node.osoutput(luaprint)

-- disable all output completely
node.osoutput(nil)

node.readvdd33() --deprecated

Moved to adc.readvdd33().

node.restart()

Restarts the chip.

Syntax

node.restart()

Parameters

none

Returns

nil

node.restore()

Restores system configuration to defaults using the SDK function system_restore(), which doesn't document precisely what it erases/restores.

Syntax

node.restore()

Parameters

none

Returns

nil

Example

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

node.setcpufreq()

Change the working CPU Frequency.

Syntax

node.setcpufreq(speed)

Parameters

speed constant 'node.CPU80MHZ' or 'node.CPU160MHZ'

Returns

target CPU frequency (number)

Example

node.setcpufreq(node.CPU80MHZ)

node.sleep()

Enters light sleep mode, which saves power without losing state. The state of the CPU and peripherals is preserved during light sleep and is resumed once the processor wakes up. When the processor wakes back up depends on the supplied options. Wake up from light sleep can be triggered by a time period, or when a GPIO (or GPIOs) change level, when a touchpad event occurs, when data is received on a UART, or by the ULP (ultra low power processor, generally not used by NodeMCU). If multiple different wakeup sources are specified, the processor will wake when any of them occur. The return value of the function can be used to determine which source caused the wakeup. The function does not return until a wakeup occurs (and therefore may not return at all if a wakeup trigger never happens).

UART buffers are not flushed on entering light sleep, rather they are suspended and resumed on wakeup, meaning that some data written before entering light sleep may not be output over the UART until after wakeup. Call uart.txflush() immediately before the node.sleep() call to ensure any pending data is output prior to the sleep.

Timers created with tmr will not fire during light sleep, and the time spent sleeping is not factored in to their remaining time after wakeup. They are paused, and resumed automatically after wakeup. For example, if a timer has 2 seconds remaining when light sleep starts, it will still have 2 seconds remaining after wakeup, regardless of how much time elapsed during the sleep or what triggered the wakeup. The value returned by node.uptime() however is updated by however long is spent in light sleep, and can therefore be used to calculate how much time was spent asleep.

Although a time period to sleep for can be specified in microseconds, the actual amount of time spent asleep will not be that precise.

Unlike with the dsleep() API, any GPIO (not just the RTC-capable pins) may be used to trigger wakeup from light sleep. To configure which GPIOs should trigger wakeup, and under what circumstances, call gpio.wakeup() prior to calling node.sleep(). If a GPIO wakeup occurs, then any callbacks configured with gpio.trig() will be called as normal after wakeup. In other words, interrupts do not get 'lost' during light sleep, and all other state such as pullups and drive strength is preserved.

Similarly, if touch = true is specified and a touch event triggers wakeup, the touch callback will be called as normal after wakeup.

Wakeup from light sleep can also be triggered by incoming data on UART0 or UART1, (but not UART2) by passing in uart = 0 or uart = 1 (or uart = {0, 1} to wake on either). Note that the byte(s) which trigger the wakeup are consumed in the process, and will therefore not be seen by the UART after wakeup. Before using uart wakeup for the first time, you must call uart.wakeup() to configure what data should trigger wakeup.

WiFi and Bluetooth must be switched off before entering light sleep, otherwise an error will be thrown.

Syntax

node.sleep(options)

Parameters

• options, a table containing some of:
  • secs, a number of seconds to sleep. This permits longer sleep periods compared to using the us parameter.
  • us, a number of microseconds to sleep. If both secs and us are provided, the values are combined.
  • gpio, a boolean, whether to allow wakeup by GPIOs. Default is false if not specified.
  • touch, boolean, whether to trigger wakeup from any previously-configured touchpads. Default is false if not specified.
  • uart, an integer or list of integers. Which UARTs should trigger wakeup. Default is the empty list if not specified.
  • ulp, a boolean, whether to allow the ULP to trigger wakeup. Default is false if not specified.

If an empty options table is specified, ie no wakeup sources, then the chip will light sleep forever with no way to wake it (except for power cycling or triggering the reset pin/button).

Returns

One of the following values, depending on what triggered the wakeup.

• node.wakeup.GPIO
• node.wakeup.TIMER
• node.wakeup.TOUCHPAD
• node.wakeup.UART
• node.wakeup.ULP

Example

-- sleep 10 seconds then continue
node.sleep({ secs = 10 })

-- sleep until 10 seconds have elapsed or either of GPIO 13 or 15 becomes high
gpio.wakeup(13, gpio.INTR_HIGH)
gpio.wakeup(15, gpio.INTR_HIGH)
node.sleep({ secs = 10, gpio = true })

-- Sleep forever until a previously-configured touchpad is touched, or a byte
-- arrives on UART0.
uart.wakeup(0, 3)
wakereason = node.sleep({ touch = true, uart = 0 })
if wakereason == node.WAKEUP_TOUCHPAD then
    print("Woken up by touchpad!")
end

See also

• node.dsleep()
• gpio.wakeup()
• uart.wakeup()

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()

node.osprint()

Controls whether the debugging output from the Espressif SDK is printed. Note that this is only available if the firmware is build with DEVELOPMENT_TOOLS defined.

####Syntax node.osprint(enabled)

Parameters

• enabled This is either true to enable printing, or false to disable it. The default is false.

Returns

Nothing

Example

node.osprint(true)

node.uptime()

Returns the value of the system counter, which counts in microseconds starting at 0 when the device is booted. Because a 32-bit signed integer can only fit 35 minutes' worth of microseconds before wrapping, when using integer-only 32-bit Lua this API returns 2 results, the first being the bottom 31 bits of the counter, and the second being the next 31 bits (ie bits 31 through 62 of the underlying 64-bit counter).

Therefore the first result will wrap back to 0 after about 35 minutes (2^31 microseconds), at which point the second result will increment by one. It is important to consider both values, or otherwise handle the first result wrapping, when for example using this function to debounce or throttle GPIO input.

When using floating-point Lua, hundreds of years of microseconds can fit in a single value with no loss of precision. In such configurations, the first result will be the bottom 53 bits of the system counter as a floating-point number, and the second result will be the top 11 bits, which in practice will always be zero unless the system counter exceeds 285 years.

Syntax

node.uptime()

Parameters

none

Returns

Two results lowbits, highbits. The first is the time in microseconds since boot or the last time the counter wrapped, and the second is the number of times the counter has wrapped. Depending on whether Lua was compiled with floating-point support or not determines when the counter wraps.

Example

print(node.uptime())
print(node.uptime())

lowbits, highbits = node.uptime()
print(lowbits, "microseconds have elapsed since the uptime last wrapped")
print(string.format("Uptime has wrapped %d times", highbits))

node.egc module

node.egc.setmode()

Sets the Emergency Garbage Collector mode. The EGC whitepaper provides more detailed information on the EGC.

####Syntax node.egc.setmode(mode, [param])

Parameters

• mode
  • node.egc.NOT_ACTIVE EGC inactive, no collection cycle will be forced in low memory situations
  • node.egc.ON_ALLOC_FAILURE Try to allocate a new block of memory, and run the garbage collector if the allocation fails. If the allocation fails even after running the garbage collector, the allocator will return with error.
  • node.egc.ON_MEM_LIMIT Run the garbage collector when the memory used by the Lua script goes beyond an upper limit. If the upper limit can't be satisfied even after running the garbage collector, the allocator will return with error.
  • node.egc.ALWAYS Run the garbage collector before each memory allocation. If the allocation fails even after running the garbage collector, the allocator will return with error. This mode is very efficient with regards to memory savings, but it's also the slowest.
• level in the case of node.egc.ON_MEM_LIMIT, this specifies the memory limit.

Returns

nil

Example

node.egc.setmode(node.egc.ALWAYS, 4096) -- This is the default setting at startup. node.egc.setmode(node.egc.ON_ALLOC_FAILURE) -- This is the fastest activeEGC mode.

node.task module

node.task.post()

Enable a Lua callback or task to post another task request. Note that as per the example multiple tasks can be posted in any task, but the highest priority is always delivered first.

If the task queue is full then a queue full error is raised.

####Syntax node.task.post([task_priority], function)

Parameters

• task_priority (optional)
  • node.task.LOW_PRIORITY = 0
  • node.task.MEDIUM_PRIORITY = 1
  • node.task.HIGH_PRIORITY = 2
• function a callback function to be executed when the task is run.

If the priority is omitted then this defaults to node.task.MEDIUM_PRIORITY

Returns

nil

Example

for i = node.task.LOW_PRIORITY, node.task.HIGH_PRIORITY do 
  node.task.post(i,function(p2)
    print("priority is "..p2)
  end) 
end      

prints

priority is 2
priority is 1
priority is 0