Block diagram itself is pretty much self explanatory. Drafting schema is not a tough job but, You need to simultaneously take care of the part that you are selecting for - footprint, availability and Pricing.

Undoubtedly, EAGLE is superior CAD tool, no matter How small or Big is your project. I have been using EAGLE for past 2 Years, And I still discover NEW things everyday.

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MCU +3V3 Powerd | 8MHz Clocked:

28-PinDIP, for easy Plug-Play and Programming, In case You end-up burning one.

POWER:

LM1117 LDO for +3V3 Regulation and DC Power Jack which allows you to power the board over 9V/12V Power adapter.

GPIO:

As stated in details related board, Inspired from Real Bare Bones.

FTDI Header:

Simple and Easy USB-to-TTL interface for Burning sketches, Serial debugging.

ESP8266[ESP-01]:

+3V3 Powered Low Cost ESP-01 module. Easily available in electronics market or Online ebay/Amazon etc.

MCP9700:

Widely used in industry for Cold Junction compensation and other applications. Output in 10mV/DegC.

LDR:

Light Dependent resistor, See how easy it is to interface. On the next second you can start playing with it, building cool applications.