My New Toy (Part 2)

In the previous post, I implemented a simple counter with serial output and today I improved it.  The main reason I purchased the ESP8266 module in the first place was to get WiFi for cheap, so I wanted to try out the WiFi capabilities.  The resulting sketch is still a counter, but instead of publishing the count via the serial interface, it connects wirelessly to a database and publishes the count there.

To begin with, I needed a simple database that I could access via HTTP.  Redis is a simple key/value type database, but it doesn’t have an HTTP interface.  I found Webdis “A fast HTTP interface for Redis”.  To set things up quickly, I found that someone had already put everything together and published a Docker image on DockerHub.  So, through the magic of Docker, all I had to do to get Redis and Webdis up and running on my computer was run this magic command:

docker run -d -p 7379:7379 -e LOCAL_REDIS=true anapsix/webdis

I then wrote a sketch that would publish to my new database:

#include <ESP8266WiFi.h>
const char* ssid = "name of wifi network";
const char* pass = "wifi network password";
const char* ip = "192.168.1.35";
const int port = 7379;
int count = 0;

void setup() {
  WiFi.begin(ssid, pass);
  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
  }
}

void loop() {
  delay(5000);
  WiFiClient client;
  client.connect(ip, port);
  String url = String("/SET/count/") + count++;
  client.print(String("GET ") + url + " HTTP/1.1\r\n" +
               "Host: " + String(ip) + "\r\n" + 
               "Connection: close\r\n" + 
               "Content-Length: 0\r\n" + 
               "\r\n");
}

Basically, it connects to the wifi network (ssid) using the provided password (pass) and then publishes the count to the database (located at ip).  It publishes the new count value every five seconds.

To verify that it was working, I simply plugged this URL into my web browser :

192.168.1.35.7379/GET/count

It returns the current value of count:

So now I can not only program my new toy, but also use some of its wireless capabilities.  It’s not useful, but it is a good step to learning how to use the ESP8266.

Author: Nathan

I like to do stuff. View all posts by Nathan