nodemcu-firmware/docs/modules/console.md

Console Module

Since	Origin / Contributor	Maintainer	Source
2024-10-22	jmattsson	jmattsson	console.c

The console modules allows direct access to the system console. The system console has typically been a UART, but by now several options are available across the ESP32 range of SoCs, including UART, USB-Serial-JTAG and USB CDC-ACM.

By default the system console is linked up to provide an interactive Lua shell (REPL — Read-Execute-Print Loop). It also provides a hook for listening in on the data received on the console programatically, and the interactivity may also be disabled (and re-enabled) programatically if so desired.

console.on()

Used to register or deregister a callback function to handle console events.

Syntax

console.on(method, [number/end_char], [function])

Parameters

• method. One of
  • "data" for bytes received on the console
  • "error" if an error condition is encountered on the console
• number/end_char. Only for event data.
  • if pass in a number n, the callback will called when n chars are received.
  • if n=0, will receive every char in buffer.
  • if pass in a one char string "c", the callback will called when "c" is encounterd, or max n=255 received.
• function callback function.
  • event "data" has a callback like this: function(data) end
  • event "error" has a callback like this: function(err) end

To unregister the callback, specify nil as the function.

Returns

nil

Example

-- when 4 chars is received.
console.on("data", 4,
  function(data)
	print("received from console:", data)
	if data=="quit" then
	  console.on("data", 0, nil)
	end
end)
-- when '\r' is received.
console.on("data", "\r",
  function(data)
	print("received from console:", data)
	if data=="quit\r" then
	  console.on("data", 0, nil)
	end
end)

-- error handler
console.on("error",
  function(err)
	print("error on console:", err)
  end)

console.mode()

Controls the interactivity of the console.

Syntax

console.mode(mode)

Parameters

• mode One of
  • console.INTERACTIVE automatically pass console data to the Lua VM for execution. This is the default mode.
  • console.NONINTERACTIVE disables the automatic passing of console data to the Lua VM. The data only goes to the registered "data" callback, if any.

Returns

nil

Example

-- Implement a REL instead of the usual REPL
console.on("data", "\r", function(line) node.input(line.."\r\n") end)
console.mode(console.NONINTERACTIVE)