Heard of Multiplexing?? what about Charlieplexing!

Well as you know multiplexing is a method to communicate more data with a lesser existing channel or time. Just to sound similar because of a analogy char…plexin is called so.

 

Charlieplexing is method to drive more number of LED’s from very less number of pins. Now there are loads of pages talking about this method on the internet. I found most of the very vague. I have tried to assimilate them together here on my page. So here it goes,

 

It is a method of driving many number of Led’s with lesser number of drive pins. One simple analogy being, if you wanted to drive 6 Leds in some sequence how many microcontroller pins would you want?You would say 6. Why just you!! most would say 6.

 

These days we have 40 Pin microcontrollers which makes the value of each I/O pin really less. But first let me explain you the context. in small series of microcontrllers which would just have 5 pins, it is impossible to drive 6 Led’s with our concept of using a single pin for one LED.

 

Well i can hear you say that you can use a multiplexer!! a 3 to 7 Mux or something?? well i would say you are not wrong, charplieplexing provides an amazing method when in goes to huge numbers.

Concept:

Say we have 3 pins A,B,C of a microcontrollers. We can connect 6 LED’s in a combination such that,

 

When A=5v , B=0v we’l have LED1 glowing and all other LED’s off
When A=0v, B=5v we’l have LED2 glowing and all other LED’s off

 

Pair LED1 and LED2 are a complimentary pair. Similarly we can have 3 such pairs and control all 6 led’s form 3 pins.

 

I am very sure you are not clear about the concept.. Well you must read this to understand the concept completely. Link goes to instructables

Swimming Snake Robot !!

Here and there at times i post few videos from you tube. even if they are my own videos i do host them to youtube and embed here in wp. Well just browsing i found this video of a swimming snake robot. I have seen many beam based land robots that twist and turn around to move. This one is a masterpiece. It swims in the water with elegance and absolutely gentle . The video doesnt give a complete design details of the bot, but the author does explain and show few things on the videos. I just mean to give my blog readers some new input of the way robotics is proceeding. Have a look.

 

 

Madan

Share Internet connection in a network – Part 2

By now you must have completed the intial setup as described in part 1
A) On the host computer

1) Goto : Start > Settings > Control pannel

2) Click on ‘Network Connections’
3) Right Click ‘Local Are Connection’ and click on properties.

4) In the ‘General Tab’ Select from ‘This connection uses the following items’
Select ‘Internet Protocol TCP/IP’ and click properties.

5) In the properties window fill the following ip configurations and click ok

B) On the Client Computer

1) Repeat steps 1 to 5
2) In stpe 5 change the ip address to : 192.168.0.2
3) Change the Default gateway to : 192.168.0.1

By doing this your client computer will connect to the internet with the default gateway of 192.168.0.1 which is your host computer.

Share Internet connection in a network – Part 1

STEPS TO SHARE INTERNET CONNECTION OVER A LAN

Do you want to connect two computers over a LAN using a ethernet cable and use a single internet connection on both computers? Then this topic is just right for you. You can connect computers and laptops – one to one conncetion using crossover cables. Crossover cables can be built with parallel ports and serial ports. But here i discuss the simple method using the ethernet cable.

Requirements:

1) Both computers must have a ethernet card and the socket.

First decide on which computer is going to act as the host computer and which computer will be the client.

Procedure To setup LAN with internet connection facility:

Setup host Computer:

Goto start>programs>accessories>communication>Network setup wizard wizard
1)Next
2)Next
3)Specify This computer connects directly to the Internet.

4)If the computer has more than one network connection, this screen appears. Specify Let me choose the connections to my network and click Next.

5)Select the connection to the ICS server and click Next.

6)Enter a computer description and computer name. The description appears in My Network Places or Network Neighborhood on other networked computers. The computer name must be unique on the network. For maximum compatibility with all versions of Windows, use 1-12 alphanumeric characters, with no blanks.

7)Enter a workgroup name, which should be the same on all of the networked computers. Once again, use 1-12 alphanumeric characters, with no blanks. Be default, the Wizard uses the name MSHOME. If your network uses a different name, enter it here.

8)The Wizard displays the settings that you’ve made. Scroll down the list to see all of them. To change a setting, click Back. To accept the settings, click Next. To stop running the Wizard, click Cancel.

9) The Wizard then configures the computer’s network settings. The process may appear to stop for a time, but let it continue to completion.

10) If the Wizard is running on a Windows XP computer, this screen appears. Specify Just finish the wizard and click Next.

11)When the configuration is complete, the Wizard’s Completion screen appears. Click Finish to exit
.

12) Restart the computer when prompted

Set the client computer:

Goto start>programs>accessories>communication>Network setup wizard wizard

1)Specify This computer connects to the Internet through another computer (the ICS server), and click Next.

2)If the computer has more than one network connection, this screen appears. Specify Let me choose the connections to my network and click Next.

3)Select the connection to the ICS server and click Next.

4)Enter a computer description and computer name. The description appears in My Network Places or Network Neighborhood on other networked computers. The computer name must be unique on the network. For maximum compatibility with all versions of Windows, use 1-12 alphanumeric characters, with no blanks.

5)Enter a workgroup name, which should be the same on all of the networked computers. Once again, use 1-12 alphanumeric characters, with no blanks. Be default, the Wizard uses the name MSHOME. If your network uses a different name, enter it here.

6)The Wizard displays the settings that you’ve made. Scroll down the list to see all of them. To change a setting, click Back. To accept the settings, click Next. To stop running the Wizard, click Cancel.

7) The Wizard then configures the computer’s network settings. The process may appear to stop for a time, but let it continue to completion.

8) If the Wizard is running on a Windows XP computer, this screen appears. Specify Just finish the wizard and click Next.

9)When the configuration is complete, the Wizard’s Completion screen appears. Click Finish to exit.

10) Restart the computer when prompted

After both computers are restarted: Test the connection :

To test if the connection is established , goto run>command
Then type : Ping 192.168.09.2 from the host computer. it must return values and results and not say time out!!!.

This test will just test the connectivity of both computers . The final step is yet to be followed where we will share our internet connection..If you have completed till this step you will be able to share datas over the LAN connection.

Long back for robocon

 

I had almost left this un-published . For last year robocon me and my friend had made one of these pick and place robots. The total cost i estimate was around 3.5K per robot. At the contest we encountered robots that were made for a Lakh of money. If you take up the cost to performance ratio i think We really were at the top

Watch our test robot.

Madan

Reverse engineering

Internet provides so many cool ideas and projects with PIC microcontrollers and other Uc’s . Unlike in this blog , most examples will contain pre-compiles ASM or machine codes along with the example. All you will be able to do is just burn it into your Uc and use. The logic thoug explained will not be clear in the program.

What reverse engineering am i talking about?
If you didn’t know , All latest microcontrollers have their code written in ‘C’ Language. Softwares called compilers convert them into machine code and ASM.

Now i am looking for a product that can convert the ASM/machine codes given in those examples to understandable ‘C’ code. Thus making  understanding and upgradation easier.Hope to see one such product soon online!!

International Robotics Olympiad

If you are a desi geek into robotics then you must try yourself at the international contest. International robotics Olympiad 2007 is going to be held at Singapore from November 27th to 30th.

If you are too young probably your mom will not let you all the way there!! .These are the contest for the above 18 age group to Singapore.

Robo Basketball
Robo Boxing
Robo Marathon
Robo BalancingBeam
Robo WeightLifting
RoboSoccer (Hurosot)

Most of the robots are meant to be autonomous. The not very popular IROC seems to have showcased some good robots last year. I’d given a good-full search for the videos but the one below was the only and the most impressive of all.