I have never needed to use WiFi in any of my projects thus far and I always assumed it would be pretty hard to integrate. I came across the ESP8226 very lately (2015) and after reading many online references I thought I'd give it a shot.
I purchased the latest and greatest ESP-13 for a few bucks($3) together with a FTDI ($2) off e-bay I had no idea why I needed the FTDI except that it was mentioned in quite a few online ESP tutorials.
For this topic, some background is required to set the scene.
In order to communicate/program the ESP-13 module we need to be able to send serial communication from our PC to the ESP device. Future Technology Devices International (FTDI) is a company that makes USB->Serial ICs. One famous one that I have purchased is the FT232RL. (notice the 232 reference i.e from back in the RS232 days). The module that I purchased off e-bay allows our PCs to expose a serial port over USB and send serial communication to an external device on COM ports. (Side note, if you had a very old PC with a serial port you would not need this FTDI board).
Now to the magical ESP chip manufactured by Espressif Systems. The ESP8266 is a module that incorporates a Microcontroller IC and a Flash storage IC. The microcontroller is pretty sweet in that is operates in the 40 ->160MHz range and with the external flash you can have access to 2MB of storage.
So the ESP is a microcontroller with some storage... but how the heck do I use it?
Reminder that I'm a noob with regards to these ESP chips so this is my understanding.
The ESP-13 (or any other ESP module) can be run as is because it is has preset/preloaded WiFi software stack. what does this mean? It can detect//connect/transmit over WiFi using a few commands that it understands (AT commands). AT commands refer to the Hayes command set commonly used to communicate with modems. AT stands for ATtention. So by supplying the chip with power and setting a few configuration pins accordingly (as defined in the datasheet) you can effectively boot the device into a "slave mode" config. In this mode the RX/TX lines allow us to send and receive AT command and information between our PC and the ESP module.
Alternatively the ESP module can be used as a microcontroller that runs your code. Remember the microcontroller is used to facilitate the WiFi software stack but like any microcontroller has GPIO, PWM, ADC, UART, I2C, I2S, IRDA functionality. This means that you can write your own code and program it directly to this chip. (<--- I have not used this method yet)
The ESP-13 module that I bought has printed on it ESP_WROOM_02 this is t he datasheet that you will find on the Espressif site. To use this chip, I needed to solder (with great precision) a break out board to use it on breadboard.
To be continued...