NEXTION THE 16×2? Fancy screens for your DIY projects.

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Gone are the days when I used to believe the coolest facelift for any project was 16×2 LCD display. For a 90’s kid(me duh),  It really took me years to realize the painful connections and interfacing procedures behind the 16*2 until I got my hands on it. Woeful soldering and drooping connections and missed out connections stole my precious hours on vicious projects.

While, it’s safe to say the display is still the popular choice among project doers, I urge them to look at the alternative – NEXTION 2.4” or more size if you’d like to. The 4D systems display is an alternative, but it would burn a hole in your pocket unless for an industrial grade product.

LCD-

The nextion is just 4 wires with 5V,GND,Rx,Rx wires making it highly compatible to any microcontroller with UART interface. A touch screen interface to control and display all sorts of sensors, motors, leds, progress bars, virtual buttons, logos and what not? Well, definitely not videos.

Understandably, It costs 1400 and the 200 for 16×2 LCD, But it’s totally worth the looks and credibility for your projects.

GOOD NEWS!!!!!!!!

The nextion comes with an ITEAD IDE which enables the user to pick and drop components and compile it and even to emulate it before deploying it to the device. All, with the simple knowledge to C++ which you would have sufficed from your Arduino.

 

 

So? Pick up one and get started…….

 

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My Take on Lua – The embedded language

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lua

 

Lua is a powerful, efficient, lightweight, embeddable scripting language. It supports procedural programming, object-oriented programming, functional programming, data-driven programming, and data description.

Lua combines simple procedural syntax with powerful data description constructs based on associative arrays and extensible semantics. Lua is dynamically typed, runs by interpreting byte code with a register-based virtual machine, and has automatic memory management with incremental garbage collection, making it ideal for configuration, scripting, and rapid prototyping. However, My first take on Lua was when I started with the esp8266 wifi module. Though, most beginners would program the module with Arduino, I’d advise to begin with Lua which is relatively easy when understood. It comes of more handy when you deal with web pages and java scripting. My observation was the arduino programs took much less memory footprint that of the Lua. Lua is more suitable when you go for higher end applications. Below are the useful commands.

 

 

 

  1. — Prints to the screen (Can end with semicolon)
    print(“Hello World”)
    –[[
    Multiline comment
    ]]
    — Variable names can’t start with a number, but can contain letters, numbers
    — and underscores
    — Lua is dynamically typed based off of the data stored there
    — This is a string and it can be surrounded by ‘ or “
    name = “Derek”
    — Another way to print to the screen
    — Escape Sequences : \n \b \t \\ \” \’
    — Get the string size by proceeding it with a #
    io.write(“Size of string “, #name, “\n”)
    — You can store any data type in a variable even after initialization
    name = 4
    io.write(“My name is “, name, “\n”)
    — Lua only has floating point numbers and this is the max number
    bigNum = 9223372036854775807 + 1
    io.write(“Big Number “, bigNum, “\n”)
    io.write(“Big Number “, type(bigNum), “\n”)
    — Floats are precise up to 13 digits
    floatPrecision = 1.999999999999 + 0.0000000000005
    io.write(floatPrecision, “\n”)
    — We can create long strings and maintain white space
    longString = [[
    I am a very very long
    string that goes on for
    ever]]
    io.write(longString, “\n”)
    — Combine Strings with ..
    longString = longString .. name
    io.write(longString, “\n”)
    — Booleans store with true or false
    isAbleToDrive = true
    io.write(type(isAbleToDrive), “\n”)
    — Every variable gets the value of nil by default meaning it has no value
    io.write(type(madeUpVar), “\n”)
    — ———- MATH ———-
    io.write(“5 + 3 = “, 5+3, “\n”)
    io.write(“5 – 3 = “, 5-3, “\n”)
    io.write(“5 * 3 = “, 5*3, “\n”)
    io.write(“5 / 3 = “, 5/3, “\n”)
    io.write(“5.2 % 3 = “, 5%3, “\n”)
    — Shorthand like number++ and number += 1 aren’t in Lua
    — Math Functions: floor, ceil, max, min, sin, cos, tan,
    — asin, acos, exp, log, log10, pow, sqrt, random, randomseed
    io.write(“floor(2.345) : “, math.floor(2.345), “\n”)
    io.write(“ceil(2.345) : “, math.ceil(2.345), “\n”)
    io.write(“max(2, 3) : “, math.max(2, 3), “\n”)
    io.write(“min(2, 3) : “, math.min(2, 3), “\n”)
    io.write(“pow(8, 2) : “, math.pow(8, 2), “\n”)
    io.write(“sqrt(64) : “, math.sqrt(64), “\n”)
    — Generate random number between 0 and 1
    io.write(“math.random() : “, math.random(), “\n”)
    — Generate random number between 1 and 10
    io.write(“math.random(10) : “, math.random(10), “\n”)
    — Generate random number between 1 and 100
    io.write(“math.random(1,100) : “, math.random(1,100), “\n”)
    — Used to set a seed value for random
    math.randomseed(os.time())
    — Print float to 10 decimals
    print(string.format(“Pi = %.10f”, math.pi))
    — ———- CONDITIONALS ———-
    — Relational Operators : > < >= <= == ~=
    — Logical Operators : and or not
    age = 13
    if age < 16 then
        io.write(“You can go to school”, “\n”)
        local localVar = 10
    elseif (age >= 16) and (age < 18) then
        io.write(“You can drive”, “\n”)
    else
        io.write(“You can vote”, “\n”)
    end
    — A variable marked local is local only to this if statement
    — io.write(“Local Variable : “, localvar)
    if (age < 14) or (age > 67) then io.write(“You shouldn’t work\n”) end
    — Format, convert to string and place boolean value with string.format
    print(string.format(“not true = %s”, tostring(not true)))
    — There is no ternary operator in Lua
    — canVote = age > 18 ? true : false
    — This is similar to the ternary operator
    canVote = age > 18 and true or false
    io.write(“Can I Vote : “, tostring(canVote), “\n”)
    — There is no Switch statement in Lua
    — ———- STRINGS ———-
    quote = “I changed my password everywhere to ‘incorrect.’ That way when I forget it,it always reminds me, ‘Your password is incorrect.'”
    io.write(“Quote Length : “, string.len(quote), “\n”)
    — Return the string after replacing
    io.write(“Replace I with me : “, string.gsub(quote, “I”, “me”), “\n”)
    — Find the index of a matching String
    io.write(“Index of password : “, string.find(quote, “password”), “\n”)
    — Set characters to upper and lowercase
    io.write(“Quote Upper : “, string.upper(quote), “\n”)
    io.write(“Quote Lower : “, string.lower(quote), “\n”)
    — ———- LOOPING ———-
    i = 1
    while (i <= 10) do
      io.write(i)
      i = i + 1
      — break throws you out of a loop
      — continue doesn’t exist with Lua
      if i == 8 then break end
    end
    print(“\n”)
    — Repeat will cycle through the loop at least once
    repeat
      io.write(“Enter your guess : “)
      — Gets input from the user
      guess = io.read()
      — Either surround the number with quotes, or convert the string into
      — a number
    until tonumber(guess) == 15
    — Value to start with, value to stop at, increment each loop
    for i = 1, 10, 1 do
      io.write(i)
    end
    print()
    — Create a table which is a list of items like an array
    months = {“January”, “February”, “March”, “April”, “May”,
    “June”, “July”, “August”, “September”, “October”, “November”,
    “December”}
    — Cycle through table where k is the key and v the value of each item
    for k, v in pairs(months) do
      io.write(v, ” “)
    end
    print()
    — ———- TABLES ———-
    — Tables take the place of arrays, dictionaries, tuples, etc.
    — Create a Table
    aTable = {}
    — Add values to a table
    for i = 1, 10 do
      aTable[i] = i
    end
    — Access value by index
    io.write(“First Item : “, aTable[1], “\n”)
    — Items in Table
    io.write(“Number of Items : “, #aTable, “\n”)
    — Insert in table, at index, item to insert
    table.insert(aTable, 1, 0)
    — Combine a table as a String and seperate with provided seperator
    print(table.concat(aTable, “, “))
    — Remove item at index
    table.remove(aTable, 1)
    print(table.concat(aTable, “, “))
    — Sort items in reverse
    table.sort(aTable, function(a,b) return a>b end)
    print(table.concat(aTable, “, “))
    — Create a multidimensional Table
    aMultiTable = {}
    for i = 0, 9 do
      aMultiTable[i] = {}
      for j = 0, 9 do
        aMultiTable[i][j] = tostring(i) .. tostring(j)
      end
    end
    — Access value in cell
    io.write(“Table[0][0] : “, aMultiTable[1][2], “\n”)
    — Cycle through and print a multidimensional Table
    for i = 0, 9 do
      for j = 0, 9 do
        io.write(aMultiTable[i][j], ” : “)
      end
      print()
    end
    — ———- FUNCTIONS ———-
    function getSum(num1, num2)
      return num1 + num2
    end
    print(string.format(“5 + 2 = %d”, getSum(5,2)))
    function splitStr(theString)
      stringTable = {}
      local i = 1
      — Cycle through the String and store anything except for spaces
      — in the table
      for str in string.gmatch(theString, “[^%s]+”) do
        stringTable[i] = str
        i = i + 1
      end
      — Return multiple values
      return stringTable, i
    end
    — Receive multiple values
    splitStrTable, numOfStr = splitStr(“The Turtle”)
    for j = 1, numOfStr do
      print(string.format(“%d : %s”, j, splitStrTable[j]))
    end
    — Variadic Function recieve unknown number of parameters
    function getSumMore(…)
      local sum = 0
      for k, v in pairs{…} do
        sum = sum + v
      end
      return sum
    end
    io.write(“Sum : “, getSumMore(1,2,3,4,5,6), “\n”)
    — A function is a variable in that we can store them under many variable
    — names as well as in tables and we can pass and return them though functions
    — Saving an anonymous function to a variable
    doubleIt = function(x) return x * 2 end
    print(doubleIt(4))
    — A Closure is a function that can access local variables of an enclosing
    — function
    function outerFunc()
      local i = 0
      return function()
        i = i + 1
        return i
      end
    end
    — When you include an inner function in a function that inner function
    — will remember changes made on variables in the inner function
    getI = outerFunc()
    print(getI())
    print(getI())
    — ———- COROUTINES ———-
    — Coroutines are like threads except that they can’t run in parallel
    — A coroutine has the status of running, susepnded, dead or normal
    — Use create to create one that performs some action
    co = coroutine.create(function()
      for i = 1, 10, 1 do
      print(i)
      print(coroutine.status(co))
      if i == 5 then coroutine.yield() end
      end end)
    — They start off with the status suspended
    print(coroutine.status(co))
    — Call for it to run with resume during which the status changes to running
    coroutine.resume(co)
    — After execution it has the status of dead
    print(coroutine.status(co))
    co2 = coroutine.create(function()
      for i = 101, 110, 1 do
      print(i)
      end end)
    coroutine.resume(co2)
    coroutine.resume(co)
    — ———- FILE I/O ———-
    — Different ways to work with files
    — r: Read only (default)
    — w: Overwrite or create a new file
    — a: Append or create a new file
    — r+: Read & write existing file
    — w+: Overwrite read or create a file
    — a+: Append read or create file
    — Create new file for reading and writing
    file = io.open(“test.lua”, “w+”)
    — Write text to the file
    file:write(“Random string of text\n”)
    file:write(“Some more text\n”)
    — Move back to the beginning of the file
    file:seek(“set”, 0)
    — Read from the file
    print(file:read(“*a”))
    — Close the file
    file:close()
    — Open file for appending and reading
    file = io.open(“test.lua”, “a+”)
    file:write(“Even more text\n”)
    file:seek(“set”, 0)
    print(file:read(“*a”))
    file:close()
    — ———- MODULES ———-
    — A Module is like a library full of functions and variables
    — Use require to gain access to the functions in the module
    convertModule = require(“convert”)
    — Execute the function in the module
    print(string.format(“%.3f cm”, convertModule.ftToCm(12)))
    — ———- METATABLES ———-
    — Used to define how operations on tables should be carried out in regards
    — to adding, subtracting, multiplying, dividing, concatenating, or
    — comparing tables
    — Create a table and put default values in it
    aTable = {}
    for x = 1, 10 do
      aTable[x] = x
    end
    mt = {
      — Define how table values should be added
      — You can also define _sub, _mul, _div, _mod, _concat (..)
      __add = function (table1, table2)
        sumTable = {}
        for y = 1, #table1 do
          if (table1[y] ~= nil) and (table2[y] ~= nil) then
            sumTable[y] = table1[y] + table2[y]
          else
            sumTable[y] = 0
          end
        end
        return sumTable
      end,
      — Define how table values should be checked for equality
      __eq = function (table1, table2)
        return table1.value == table2.value
      end,
      — For homework figure out how to check if less then
      __lt = function (table1, table2)
        return table1.value < table2.value
      end,
      — For homework figure out how to check if less then or equal
      __le = function (table1, table2)
        return table1.value <= table2.value
      end,
    }
    — Attach the metamethods to this table
    setmetatable(aTable, mt)
    — Check if tables are equal
    print(aTable == aTable)
    addTable = {}
    — Add values in tables
    addTable = aTable + aTable
    — print the results of the addition
    for z = 1, #addTable do
      print(addTable[z])
    end
    — ———- OBJECT ORIENTED PROGRAMMING ———-
    — Lua is not an OOP language and it doesn’t allow you to define classes
    — but you can fake it using tables and metatables
    — Define the defaults for our table
    Animal = {height = 0, weight = 0, name = “No Name”, sound = “No Sound”}
    — Used to initialize Animal objects
    function Animal:new (height, weight, name, sound)
      setmetatable({}, Animal)
      — Self is a reference to values for this Animal
      self.height = height
      self.weight = weight
      self.name = name
      self.sound = sound
      return self
    end
    — Outputs a string that describes the Animal
    function Animal:toString()
      animalStr = string.format(“%s weighs %.1f lbs, is %.1f in tall and says %s”, self.name, self.weight, self.height, self.sound)
      return animalStr
    end
    — Create an Animal
    spot = Animal:new(10, 15, “Spot”, “Roof”)
    — Get variable values
    print(spot.weight)
    — Call a function in Animal
    print(spot:toString())
    — ———- INHERITANCE ———-
    — Extends the properties and functions in another object
    Cat = Animal:new()
    function Cat:new (height, weight, name, sound, favFood)
      setmetatable({}, Cat)
      — Self is a reference to values for this Animal
      self.height = height
      self.weight = weight
      self.name = name
      self.sound = sound
      self.favFood = favFood
      return self
    end
    — Overide an Animal function
    function Cat:toString()
      catStr = string.format(“%s weighs %.1f lbs, is %.1f in tall, says %s and loves %s”, self.name, self.weight, self.height, self.sound, self.favFood)
      return catStr
    end
    — Create a Cat
    fluffy = Cat:new(10, 15, “Fluffy”, “Meow”, “Tuna”)
    print(fluffy:toString())

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TIMER FUNCTION IN APP INVENTOR

QUICK TIP : HOW TO BECOME AN APP DEVELOPER ?

  • Go to app inventor/thunkable to see how easy to create apps
  • Call yourself an App developer? DEFINETELY NO
  • UNDERSTAND HOW AN APP WORKS
  • SET REALISTIC LEARNING GOALS – ANDROID STUDIO/ECLIPSE
  • START LEARNING FOR REAL

 

For those who are on to create sample apps on third party MIT/THUNKABLE apps for arduino,raspberry, esp8066, bluetooth devices and experiments, you shall be forgiven and this post shares the crucial element of timer function below.

blocks