Arduino/Wifi
From charlesreid1
Contents
Arduino Plus Wifi
I bought a couple of 8-pin wifi boards (ESP8266) to connect with an Arduino board to add wifi to some Arduino projects. Here's a photo of one of the chips:
ESP8266 Chip
The ESP8266 chip is a serial-over-wifi chip. (Whatever that means.)
These are actually pretty nifty chips, much more nifty than I originally thought: you can hook up a GPIO to the chip, and have it act as a standalone chip running an application on its own.
From their page: "Our ESP8266 Wifi Module is a low-cost and easy-to-use alternative to expensive wifi shields. This module is built around a powerful onboard microprocessor that features a built-in TCP/IP stack which handles all of the heavy lifting - leaving your Arduino free to communicate using simple serial and AT commands."
Serial Interface
This chip has 8 pins on the board. They are not labeled clearly. To interface with this chip (from an Arduino or a Raspberry Pi or a computer), you can use a serial connection.
A serial connection typically consists of four pins:
- VIN: voltage in (3.3 V or 5 V)
- GND: ground pin
- RX: receive channel
- TX: transmit channel
Note that the receive and transmit pins are crossed when connecting two devices.
Serial Hardware
You will need some hardware to talk to the wifi chip to program it. A serial interface capable of generating 3.3 V logic signals is necessary. A separate power source for this wireless chip is also critical to ensure that the chip can draw the full 300 mA it requires.
One nice advantage of a USB-to-RS-232 serial interface is that the power source comes from another device. WHile you can only interface with this wifi chip via a computer, this is kind of the point of serial.
Linkz
Documentation
Documentation for this product from manufacturer: http://www.vetco.net/catalog/product_info.php?products_id=16958
Information about interfacing with the chip via serial: http://www.seeedstudio.com/wiki/WiFi_Serial_Transceiver_Module
Manufacturer Expressif provides a nice set of pages with info and project ideas: http://bbs.espressif.com/
github library: https://github.com/willdurand/EspWiFi/blob/master/EspWiFi.h
esp8266 wiki: http://www.esp8266.com/wiki/doku.php?id=getting-started-with-the-esp8266
Hardware
Bi-directional logic converter: 3.3V to 5V (very cheap): https://www.sparkfun.com/products/12009
3.3V to 5V analog how-to, guide, tips and tricks: http://www.newark.com/pdfs/techarticles/microchip/3_3vto5vAnalogTipsnTricksBrchr.pdf
usb-to-serial TTL usb converter hardware: https://www.adafruit.com/products/954
usb-to-serial TTL usb converter guide: http://villagescience.org/running-raspberry-pi-usb-serial-ttl-adapter/
sparkfun version of the esp8266 (more pins?): https://learn.sparkfun.com/tutorials/esp8266-thing-hookup-guide/hardware-overview
another version with more pins: http://reflowster.com/blog/2015/05/11/esp8266.html
almost exactly the same hardware, using a serial-to-TTL converter: http://williamdurand.fr/2015/03/17/playing-with-a-esp8266-wifi-module/
Arduino Sketch
This page [1] works by connecting an output signal from the Arduino to a USB-TTL serial converter chip. This signal is then sent back to the Arduino. The signal is (presumably) routed around to the Arudino's TX pin, and the Arduino's TX pin is hooked up to the Wifi chip's RX pin. Similarly, the Arduino's RX pin is hooked up to the Wifi chip's TX pin. This way, serial signals are routed through the USB-TTL converter.
#include <SoftwareSerial.h>
#define SSID "xxxxxxxx"
#define PASS "xxxxxxxx"
#define DST_IP "220.181.111.85" //baidu.com
SoftwareSerial dbgSerial(10, 11); // RX, TX
void setup()
{
// Open serial communications and wait for port to open:
Serial.begin(57600);
Serial.setTimeout(5000);
dbgSerial.begin(9600); //can't be faster than 19200 for softserial
dbgSerial.println("ESP8266 Demo");
//test if the module is ready
Serial.println("AT+RST");
delay(1000);
if(Serial.find("ready"))
{
dbgSerial.println("Module is ready");
}
else
{
dbgSerial.println("Module have no response.");
while(1);
}
delay(1000);
//connect to the wifi
boolean connected=false;
for(int i=0;i<5;i++)
{
if(connectWiFi())
{
connected = true;
break;
}
}
if (!connected){while(1);}
delay(5000);
//print the ip addr
/*Serial.println("AT+CIFSR");
dbgSerial.println("ip address:");
while (Serial.available())
dbgSerial.write(Serial.read());*/
//set the single connection mode
Serial.println("AT+CIPMUX=0");
}
void loop()
{
String cmd = "AT+CIPSTART=\"TCP\",\"";
cmd += DST_IP;
cmd += "\",80";
Serial.println(cmd);
dbgSerial.println(cmd);
if(Serial.find("Error")) return;
cmd = "GET / HTTP/1.0\r\n\r\n";
Serial.print("AT+CIPSEND=");
Serial.println(cmd.length());
if(Serial.find(">"))
{
dbgSerial.print(">");
}else
{
Serial.println("AT+CIPCLOSE");
dbgSerial.println("connect timeout");
delay(1000);
return;
}
Serial.print(cmd);
delay(2000);
//Serial.find("+IPD");
while (Serial.available())
{
char c = Serial.read();
dbgSerial.write(c);
if(c=='\r') dbgSerial.print('\n');
}
dbgSerial.println("====");
delay(1000);
}
boolean connectWiFi()
{
Serial.println("AT+CWMODE=1");
String cmd="AT+CWJAP=\"";
cmd+=SSID;
cmd+="\",\"";
cmd+=PASS;
cmd+="\"";
dbgSerial.println(cmd);
Serial.println(cmd);
delay(2000);
if(Serial.find("OK"))
{
dbgSerial.println("OK, Connected to WiFi.");
return true;
}else
{
dbgSerial.println("Can not connect to the WiFi.");
return false;
}
}
Arduino Linkz
Project is to hook up a tiny LCD to the tiny wifi chip and make a tiny wifi monitor.
Add this to the Defcon badge, which should have a microchip that is programmable via serial as well, and could be wired up to control the LCD and tiny wifi chip.
Or, just hook it up to the battery or source of power, and have it standalone, running by itself.
Inspiration: http://www.seeedstudio.com/wiki/WiFi_Serial_Transceiver_Module
LCD Hardware:
- $15 tiny LCD, 128x128, 4D systems
- round LCD (too expensive)
- mouser: round LCDs http://www.mouser.com/search/refine.aspx?Ntk=P_MarCom&Ntt=166384143
- Large enough to be useful - https://www.adafruit.com/products/1770
- 2.8 inch display large enough for tiny drawings, would be perfect.
USB-Serial Converter:
- USB to serial converter:
- FTDI provides a usb-serial adapter with a jumper to set the voltage level at 3.3 or 5, depending on what you wanna do:
- inspired by this project/page: http://williamdurand.fr/2015/03/17/playing-with-a-esp8266-wifi-module/
- USB to serial converter, other options:
- uart sbee povides BEE connections, like the usb-to-serial BEE boards that I have for the XBees, but these also have 4-pin serial header: http://www.seeedstudio.com/wiki/UartSBee_V4
Once you have all those pieces, this page becomes much more useful, and tells you what serial commands to actually run:
What about the final - logic control from Arduino, USB adapter from 5 V to 3.3 V level, etc.?
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