First Steps with ESP-01 on OS X El Capitan - Part 2

In part 1 I described how I setup my my environment. In this part I will show my first lua programming steps with the ESP8266 using the Lua based NodeMCU firmware.

First I create an init script (init.lua). This will be loaded by the firmware after each boot/restart.
As last step in the boot/restart process the firmware loads and executes the script init.lua (you can see a corresponding error message in the last screenshot in part 1).
It is recommended to provide an opportunity to interrupt the execution of init.lua to be able to change anything. Otherwise it may happen e.g. if your code contains a fatal error which cause a reboot that you are unable to deactivate/fix the code - and finally have to reflash the firmware to be break the loop.

I'm looking around an found a post about Methods of Interrupting init.lua during boot. My init.lua code based mainly on the ideas described there. But here it is:

1. it calls firmwareInfo() to output information about the firmware. For the moment it just inform if it is a FLOAT or INTEGER version
2. after a delay of BootTimeout ms (to give the NodeMCU some time to initialize it self) init() is called
3. in init() the serial port is initialized and configured to watch for a transmitted ENTER key
4. if an ENTER is received the function abort() is called, which set the abortFlag to true.
5. After AbortTimeoutms startup() is called. There the abortFlag is checked and the startup is canceled or executed by trying to load and execute 'user.lua'

The output of such a run without interrupt is shown below:

Next step was to wrote a script to read out a DHT22 sensor. The user_dht22.lua script shown below reads temperature and humidity every 2 sec and prints both values. Depending on the used firmware the output is generated using different format and in case of integer also further values.

Output running the script