# Play nodeMCU
###### tags: `RPI`

## good tutorial
https://blog.alexellis.io/iot-nodemcu-sensor-bme280/
https://nodemcu.readthedocs.io/

## Build firmware
https://nodemcu.readthedocs.io/en/master/build/#integer-build

git clone --recurse-submodules https://github.com/nodemcu/nodemcu-firmware.git
cd nodemcu-firmware
vim app/include/user_config.h
vim app/include/user_module.h
docker run --rm -it -v $PWD:/opt/nodemcu-firmware marcelstoer/nodemcu-build build

note:
You need to ensure the below module/features are enabled.
* http
* ssl
* net
* GPIO
* wifi
* MQTT
* PMSLEEP_ENABLE

## Flash firmware
https://nodemcu.readthedocs.io/en/master/flash/
https://github.com/espressif/esptool

pip3 install esptool
# use this when your program is in infinite loop
sudo esptool.py erase_flash
sudo esptool.py -p /dev/ttyUSB0 write_flash 0x00000 nodemcu-firmware/bin/nodemcu_float_master_20200210-0431.bin     

## some lua example
A webserver that toggle gpio
https://gist.github.com/linnil1/e754589d52e387f14290ea16e1151468

Send data to server every seconds
https://gist.github.com/linnil1/d5ec89f84090f8279bbb2038924abd25

### wifi connection

ssid = ""
key = ""
function connect_wifi(func)
    func = func or function() end
    print("Get wifi")
    wifi.setmode(wifi.STATION)
    station_cfg={}
    station_cfg.ssid = ssid
    station_cfg.pwd = key
    station_cfg.save = true

    wifi.eventmon.register(wifi.eventmon.STA_CONNECTED, function(T)
        print("STA - CONNECTED\nSSID: "..T.SSID.."\nBSSID: "..T.BSSID.."\nChannel: "..T.channel.."\n")
    end)

    wifi.eventmon.register(wifi.eventmon.STA_GOT_IP, function(T)
        print("IP: "..T.IP.."\nMASK: "..T.netmask.."\nGW: "..T.gateway.."\nStation ready!\n")
        func()
    end)

    wifi.sta.config(station_cfg)
end

### requests

http.get("https://ntu.edu.tw:443", nil, function(code, data)
    print(code, data)
  end
)

http.post(url,
          'Content-Type: application/json\r\n',
          '{"status": "..s.."}', function(code, data)
    if (code < 0) then
        fail_func()
    else
        print(code, data)
    end
  end
)

### file read write

-- list
l = file.list();
for k,v in pairs(l) do
  print("name:"..k..", size:"..v)
end

-- read
if file.open("txt") then
  print(file.read())
  file.close()
end

-- write
if file.open("txt", "w") then
  file.write('foo bar')
  file.close()
end

### gpio
https://www.electronicwings.com/nodemcu/nodemcu-gpio-with-esplorer-ide
https://nodemcu.readthedocs.io/en/master/modules/gpio/

LEDpin = 8         -- Declare LED pin no.
gpio.mode(LEDpin, gpio.OUTPUT)
gpio.write(LEDpin, gpio.HIGH)
gpio.write(LEDpin, gpio.LOW)

-- blink once in 300ms
gpio.write(LEDpin, gpio.LOW)
tmr.create():alarm(300, tmr.ALARM_SINGLE, function()
    gpio.write(LEDpin, gpio.LOW)
end)

### http server

sv = net.createServer(net.TCP, 30)

-- response data for request
function send(sck, message)
    print(message)
    sck:send("HTTP/1.1 200 OK\r\nContent-Type: application/json\r\n\r\n")
    sck:send('{"status":"'..message..'"}', function()
        sck:close()
    end)
end

-- Create a web server
function web_server()
    function receiver(sck, data)
      print(data)
      send(sck, "Hello World")
    end

    if sv then
      sv:listen(80, function(conn)
        conn:on("receive", receiver)
      end)
    end
end

### other

node.restart()
file.rename(a, b)
file.remove(a)

### Note: Don't use tmr.delay
https://nodemcu.readthedocs.io/en/master/modules/tmr
use alarm instead.

tmr.create():alarm(1000, tmr.ALARM_AUTO, function(mytmr)  -- 100ms
    if (something) then
        mytmr.unregister(mytmr)
    else
        do_something()
    end
end

### deep sleep
https://nodemcu.readthedocs.io/en/master/modules/node/#nodedsleep
`node.dsleep(1 * 1000000)`(1second)
and connect D0(pin16) to RST(reset)

## upload code
https://nodemcu.readthedocs.io/en/latest/upload/
https://github.com/kmpm/nodemcu-uploader

If your file name is `init.lua`, it will automatically execute it after booting.

pip3 install nodemcu-uploader
sudo nodemcu-uploader upload ./myinit.lua

testing: you will see interaction mode.

sudo screen -L /dev/ttyUSB0 115200

You can run your code like this

> dofile("myinit.lua")

## Install lua on local
https://www.lua.org/start.html

curl -R -O http://www.lua.org/ftp/lua-5.3.5.tar.gz
tar zxf lua-5.3.5.tar.gz
cd lua-5.3.5
sudo make linux install

and tutorial
https://www.tutorialspoint.com/lua/index.htm