• Abhijit Ghosh Abhijit Ghosh Posted 53 Articles A java/j2ee developer. Love to share learning experiences on different technologies/frameworks.
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Home Automation - Internet of Things - MQTT (MQ Telemetry Transport), ESP8266 and MycroPython

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By Abhijit Ghosh on Mar 22, 2017 3:51:40 AM

This is my first post on home automation. As a 'Hello World' project, switching on/off a bulb is a common use case. This post is not an exception. But to spice it up, we'll use MQTT (MQ Telemetry Transport) - a machine-to-machine (M2M)/Internet of Things (IOT) connectivity protocol and an android app (IoT MQTT Dashboard). Bulb is merely a symbolic representation of an electrical device. We can practically control any device (Internet of Things) over internet.

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Configure STA_IF interface of ESP8266 (MycroPython firmware) to connect with WIFI network automatically on boot

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By Abhijit Ghosh on Mar 14, 2017 3:06:19 AM

ESP8266 can act as both Station / WIFI client (STA_IF interface) and Access Point (AP_IF interface). AP_IF interface is active by default in MycroPython firmware on ESP826 . In the earlier post, we connected to the access point (AP mode) of ESP8266 and used WebREPL to remotely control switch on/off and brightness of an LED. Now, we'll configure the ESP8266 (as WIFI client) so that it connects to the WIFI router automatically after booting.

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Example: Remotely switch on/off and control brightness of an LED using MicroPython WebREPL

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By Abhijit Ghosh on Mar 8, 2017 1:49:40 AM

So far, we have flashed MicroPython firmware onto an ESP8266 and setup WebREPL to run programs over WIFI on the chip. Now it's time for a hands-on excercise. We'll remotely switch on/off and control brightness of an LED using MicroPython WebREPL.

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How to setup WebREPL to connect to Python prompt (REPL) of ESP8266 over WIFI network?

1,153 views
By Abhijit Ghosh on Feb 23, 2017 2:05:33 AM

WebREPL daemon auto-start is disabled by default in MycroPython on ESP8266 for security reason. Here, we'll enable the same, connect to the REPL over WIFI using locally installed WebREPL client and run a "Hello World" program remotely on the chip.

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How to flash MicroPython firmware onto an ESP8266 ESP-12E chip using esptool?

1,712 views
By Abhijit Ghosh on Feb 4, 2017 12:01:35 PM

By default, ESP8226 module comes with AT Firmware. In this post, we'll see how to flash MicroPython firmware onto an ESP8266 ESP-12E chip using esptool.

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How to uninstall OpenCV (Open Source Computer Vision) from Raspberry Pi - Raspbian Jessie?

7,736 views
By Abhijit Ghosh on Jul 10, 2016 4:05:12 PM

To uninstall OpenCV (Open Source Computer Vision) from Raspberry Pi (Raspbian Jessie), follow the steps mentioned below in this article.

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Install and Configure Oracle Java ME Embedded on Raspberry Pi

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By Abhijit Ghosh on Mar 17, 2015 10:14:14 PM

Raspberry Pi is a low cost, credit-card sized and fastest selling personal computer. In this article, we'll install and configure Oracle Java ME Embedded on a Raspberry Pi.

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Build, Install and Configure Eclipse Plugin for Apache Hadoop 2.2.0

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By Abhijit Ghosh on Apr 23, 2014 2:10:18 PM

Apache Hadoop Development Tools (HDT) is still in development phase. So, no official distribution of Hadoop 2.2.0 Eclipse Plugin is available now. But we can build the same using winghc/hadoop2x-eclipse-plugin. In this post, we'll build, install and configure the plugin with the Eclipse or any Eclipse based IDE (say, Spring Tool Suite) to ease the development activities using Hadoop framework.

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Shell$ExitCodeException - Caused by: java.lang.NoClassDefFoundError: org/apache/hadoop/service/CompositeService

42,811 views
By Abhijit Ghosh on Feb 28, 2014 1:43:45 PM

If you are getting "Exception from container-launch:org.apache.hadoop.util.Shell$ExitCodeException" in FAILED application's Diagnostics (or Command prompt) and "java.lang.NoClassDefFoundError: org/apache/hadoop/service/CompositeService" in 'stderr' containerlogs while running any Hadoop example on Windows, then add all the required Hadoop jars to the property 'yarn.application.classpath' in yarn-site.xml configuration file.

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Run Hadoop wordcount MapReduce Example on Windows

53,211 views
By Abhijit Ghosh on Feb 3, 2014 12:21:12 PM

In this post, we'll use HDFS command 'bin\hdfs dfs' with different options like mkdir, copyFromLocal, cat, ls and finally run the wordcount MapReduce job provided in %HADOOP_HOME%\share\hadoop\mapreduce\hadoop-mapreduce-examples-2.2.0.jar. On successful execution of the job in the Single Node (pseudo-distributed mode) cluster, an output (contains counts of the occurrences of each word) will be generated.

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This site is mainly developed to share coding and technology learning experiences on java / j2ee based technologies.

Simple tutorials / codes have been shared to learn a new technology. Full source code is also available for download.