Testing individual segments of a 7 Segment display

Today I took one 7 segment display from my college lab. While I’ve used these before, I saw this after a long time. Now I was trying to remember how to operate it. The one that I got was common cathode type. So in this cathode is common. Now cathode is the negative terminal of 7 segment display and needs to be grounded. So logically if you want any segment to glow you need to supply Vcc. But 7 segment display is nothing more than a group of led’s arranged in specific order and of particular shape. So like any ordinary led’s it will definitely burn if the current exceeds the rated value. That is why we normally use current limiting resistors. But testing using that set up is tedious. So we’ll learn how to test the segments using a multimeter.

One more thing, the printed code on seven segment display will have a CC mark for common cathode and A for common anode.

Above figure shows both the variants of 7 segment displays i.e the common anode and common cathode.

Steps involved in testing:

1) Keep the multimeter in diode mode.

2) Now depending upon which variant you have you’ll have to make connections.testing-diode-using-digital-multimeter

For common cathode place the negative probe of multimeter on the centre pin and then place the positive probe on the segment pin that you want to test.

For common anode place the positive probe of multimeter on the centre pin and then place the negative probe on the segment pin that you want to test.

Hope this tip will be useful.

Youtube link:


Energia + MSP430 = Arduino!!! in PDIP :D

EnergiaHello everyone. This post is regarding an IDE called Energia, for msp430 launchpad. There are millions of arduino fans out there, who love the inbuilt libraries and functions for making projects easily. Hobbyists have the natural tendency to use arduino for their projects. This is justified by the large number of  *shields that are available for arduino and the awesome arduino community.  This is a good news for them as Energia enables coding msp430 microcontrollers using the arduino libraries and functions. In fact Energia has inbuilt example ‘sketches’ just like the arduino IDE which you can build and burn in the controller.


Yes the blink led sketch and all others, you can directly set the microcontroller you want to use and get the fun started. Energia is an open source project just like arduino. It was launched in 2012 i.e last year. There have been a few updated to improve the stability. The color of Energia is red (launchpad!!) unlike arduino which is blue. Now to talk about the code efficiency and the IDE stability. Since it uses another processors IDE libraries and functions and converts it into those which are compatible with our launchpad controllers, it is slower as compared to CSS,IAR and other development environments. It may seem to test your patience, but then you are getting best of both worlds right? So one shouldn’t complain about it. So now you have various methods to reduce your coding time. If you want to interface an 16x2LCD just import the lcd library and use the inbuilt functions to perform the tasks that you require. So if a LCD is like ABCD.. type basic thing in your project you can avoid initializing those peripherals manually via control signals and command words. Makes our life easy, isn’t it?

This is the link to the Energia website if you are interested.


Here you can download the latest Energia version. There is help page as most sites have. The most important advantage of Energia is that you’ll open up the gate to a humongous community i.e arduino community.

Hope this post was informative. Thank you for reading this.

* Shield refers to a hardware that performs a specific set of tasks and can be mounted onto the arduino board. On that note I’ll like to introduce the booster packs of launchpad. Booster pack is the launchpad version of the name shield.

Code Composer Studio : Grace !!!


I recently learned about this wonderful graphical user interface(GUI) called Grace which is a part of the Code Composer Studio by Texas Instruments. I must tell you that the interface is simply amazing. I mean you can initialize all the peripherals, interrupt subroutines, interrupt handling, etc using this interface. I tried this 1 sec delay program using grace and was amazed at the fact that TI has literally make it a cake walk for programmers to initialize all peripherals and interrupts in c language. I like writing code in assembly language and for that matter even in c, but as you would come to know while programming in c you need to use some explicit functions defined by the compiler to write the various interrupt subroutines. So if you want to focus on whether your concept is correct or not and want to do testing then grace is a blessing for you. Once you know that your code is working using grace, you can anytime write the assembly language program( initializing all the peripherals using their command registers, handle the interrupt vector addresses and so on).

I’ll be covering how to make a project using grace in CCS very soon.

How to create a new project in CCS5.4

In this post I’m assuming you have already installed code composer studio after downloading it from http://processors.wiki.ti.com/index.php/Download_CCS. The steps involved are covered visually via images. The first step is to open the software by double clicking on its icon. Subsequent steps are shown below.


step3 step4 step5 step6 step7 step8 step9


1) Open code composer studio.

2)Select new->project

3)Select CSS project in the dialogue box that appears

4) Since I am using msp430g2231 I have selected that ic from the list you can choose whichever ic you intend to use. Give the project a suitable na
me. You have to select an empty project with main.c else you’ll have to manually add c file which is not that difficult but I won’t be covering that in this list.

5)Make your project as active project by clicking on it in the project explorer.

6) Expand your current project by clicking on the small plus on the folder. Then double click on the main.c to open the file.

7) Now you are ready to start the c programming in main.c

8) After writing the code you can debug it. If there are no errors then you’ll get an option to run/play the program.


About msp430 launchpad

MSP430G2 launchpad is a development board developed by Texas Instruments. The msp430g series is a series of micro-controllers. The cost of launchpad is $9.99. This is a one time investment. Once you have the launchpad, you’ll open an entire new world for yourself. Texas Instruments launchpad contains the following hardware:

  • MSP-EXP430G2 LaunchPad
  • MSP430G2553 microcontroller (with demo code)
  • MSP430G2452 microcontroller
  • Mini-USB cable
  • Quick Start Guide
  • 32kHz external crystal

(Note: You can order the board from TI itself. The link is : http://www.ti.com/tool/msp-exp430g2 )MSP-EXP30G2.jpg

Texas provides free samples of these microcontrollers. So whenever you’ll need a microcontroller, you can search their website and order free sample of whatever you like. This enables to divert you money into other electronic equipment that you require. All in all I encourage all of you people out there who like coding and controllers to get your hands on launchpad.

P.S: If you have any query regarding how to order these samples, feel free to contact me.