NETWORKING AND COMMUNICATIONS

14.WEEK

INDIVIDUAL ASSIGNMENT

This task I decided to use ESP8266-01 module. It is a Wi-Fi microchip with 32-bit microcontroller capability. he For beginner like me it is good module to start with. But on the beginning I got some small problems that I’ll talk about latter in documentation.

ESP8266-01 is little bit complicated because it does not support 5V, only 3.3V. If you don’t have a Arduino or FTDI with 3.3V pin than you will need to use resistor. The module has at least two different boot modes: ‘normal mode’ and ‘programming mode’. ‘Programming’ or ‘flashing’ refers to uploading any custom or default software or firmware to the ESP8266’s flash memory. Flashing will overwrite the previous programming/firmware (including the AT command set if that was flashed). To be able to flash new firmware onto an ESP-01 module, it needs to be connected to a FTDI.

The ESP8266 can either boot up in ‘programming’ mode or in ‘normal’ mode. While booting up, the status of GPIO0 and GPIO2 is seen as input pins (as suppose to output pins) and their voltage status is used to check which mode the ESP8266 needs to enter.

So after little briefing of board I’m ready to try it. First to do is to add in “FILE>PREFERENCES>ADDITIONAL BOARDS MANAGER URLs” this link(http://arduino.esp8266.com/stable/package_esp8266com_index.json), than I need to add the ESP8266 board and I’ll do it by go to “TOOLS>BOARD>BOARDS MANAGER>” and there is search line type ESP8266 and install the package just like on picture below.

Now when the board is successfully added I’m good to go.

First two attempts were fail for me. For first attempt I used regular FTDI USB serial converter because he has option to connect ESP8266 on 3.3V, but after I connect all pins like it’s shown in picture, I got nothing, trying to connect it other ways and still nothing, on some attempt my board started to getting hot really fast so I went to check with multi meter am I using the correct VCC pin on FTDI. But I did. And here is how I connected it.

After that tried with FTDI cable that provides 3.3V and that attempt was successful.

It’s hard to tell but the pins are connected in this order:

FTDI	ESP8266-01
RX	TX
TX	RX
VCC 3.3V	VCC
VCC 3.3V	CH_PD
GND	GND

ESP8266, in it’s default configuration, boots up into the serial modem mode. In this mode you can communicate with it using a set of AT commands. Below you can see the commands that I run in “serial monitor” to connect it to wifi.

AT: test if AT system works correctly

AT+GMR: view version info (print firmware version)

AT+CWMODE=3: WIFI mode (station, AP, station+AP)-set AP’s info which will be connected by ESP8266

AT+CWLAP: list available Aps

AT+CWJAP “DEZENTRALE”,”NixFuerKinder”: connect to AP-commands ESP8266 to connect a SSID with supplied password

AT+CIFSR: get local IP address

Those are command that I ran and can be seen on picture, for more AT commands visit ROOM-15 site where is great and detailed description for all commands.

To check does it really works I went to my wifi setting on laptop and mobile phone, it works.

And for the end of this part, a short video of working ESP8266-01 😊

GROUP ASSIGNMENT

For group assignment I’ll try I2C Bus, or as it really stands for Inter-Integrated Circuit). So this is very powerful bus used for communication between a master and slave, there can also be multiple masters and slaves.

This example shows I2C Bus for embedded system, where are multiple slaves devices used. On left, microcontroller represents master and controls all the sensors and that with only two pins.

To understand better what is and how does I2C works, visit application report from Texas Instruments. This is the site that helped me a lot to understand it and to make my next exercise easier to complete.

I will be setting up two boards, one arduino and other is Valentino (my board from week 11) to communicate using the I2C protocol. This is a simple project to take input from a push-button switch on the first Arduino, send the signal received from the button to the second ("slave").

For this asignment I will use: arduino uno, push button, Valentino(my board from week 11), LED, 2 x 220Ohm resistors and some jumper wires.

"MASTER" ARDUINO CODE

#include <Wire.h> // <-- remove spaces

int x =0;

int slaveAddress = 9;

const int buttonPin = 2; // the number of the pushbutton pin

int buttonState = 0; // variable for reading the pushbutton status

void setup()

{

pinMode( buttonPin, INPUT ); // initialize the pushbutton pin as an input

Wire.begin(); // join i2c bus (address optional for master)

Serial.begin( 9600 ); // start serial for output

}

void loop()

{

// read the state of the pushbutton value:

buttonState = digitalRead( buttonPin );

// check if the pushbutton is pressed. If it is, the buttonState is HIGH:

if ( buttonState == HIGH )

{

x = 1;

}

else

{

x = 0;

}

Wire.beginTransmission( slaveAddress ); // transmit to device #9

Wire.write(x); // sends x

Wire.endTransmission(); // stop transmitting

delay(2);

}

"SLAVE" VALENTINO BOARD

#include <Wire.h> // <-- remove spaces

int LED = 4;

int x = 0;

void setup()

{

// Define the LED pin as Output

pinMode (LED, OUTPUT);

// Start the I2C Bus as Slave on address 9

Wire.begin(9);

// Attach a function to trigger when something is received.

Wire.onReceive(receiveEvent);

}

void receiveEvent( int bytes )

{

x = Wire.read(); // read one character from the I2C

Wire.endTransmission(); // stop transmitting

}

void loop()

{

if (x == 0) {

digitalWrite(LED, HIGH);

delay(2);

}

if (x == 0) {

digitalWrite(LED, LOW);

delay(2);

}
}

Those are the codes that needs to be uploaded to each board, just be carefol to chose right port, I made that mistake once.

And like always a short video.