Thursday, November 10, 2011

Controlling Traffic Lights Using Android Phones

here is our new design where we use android phone to do manual control of a traffic lights.

Thursday, June 16, 2011

Embedded Product Development in 1995 - Problems and challenges

" It was a cold Thursday evening on Dec 1995. I was sitting in office of Max India and along with Ashish Masand was comparing numbers on a printed page with a text file on computer screen. There was no sense of those numbers, A typical line looked like this

A040 34 AE 4C 9E 2B 02 26 12 FE 86 34 CD 2D C9 06 1E

After some time I signed those papers, handed over a Demand Draft. Ashish thanked me and we moved out. Even when temperature was just 5 degree centigrade, I was sweating. Ashish asked me not to worry and said every thing will be all right and he promised that in less than 3 months, I will be getting material

And after four months of wait I got 5000 units of this material.

Well, this is how the embedded development used to happen in 1995. To design a product, you need a emulation board costing USD 2000, write code in assembly level language, try it out. Modify and continue till the results look okay. Then this program was burned in a UVEPROM ic which has a glass window on top of the ic

And then try out the unit operation. If it works fine, else this IC was put in a UV ERASER for 20 minutes and the whole operation started. After every things looks okay (which usually happens after testing for 20 to 30 days) then program was burned in similar ic without window and unit was handed over to customer for testing. He usually comes back with few bugs or some changes and process starts again.

Well, after he approves the design, the data of hex file was printed and sent to Motorola (or which ever company provided the micro controller). Motorola will resend few papers and ask for signatures. And then we compare the Motorola printed  sheet with what we printed to look for any typing mistakes and sign it.

This design will goto Motorola foundry and after a period ranging from 12 to 16 weeks, Motorola deliver 5000 or more ic printed with our special code.

These specially fabricated ICs were then used in manufacturing.

Any mistake in the document and end product will not work as expected as Motorola's guaranteed delivery of parts with information that we signed on their papers.

The fabrication of also requires a one time process charges of USD 3000/- and per piece price of USD 2 ie total of USD 13,000/-

Any small and silly mistake due to oversight costs USD 13,000/- and of course delay of four months

And this was reason for me sweating on that cold evening of December.

The reward too were high. Against a normal price of USD 6 for normal ic, we get product at USD 2.6 including the cost of one time charges. And all subsequent parts at USD 2.

Plus a feeling of pride as Motorola makes ICs with our mark on it. GVC-STC-226 stands for

me and my wife's name GVC (Geeta Vinay Chaddha)
product STC (Set Top Converter) and
Version number 2.26.

Friday, May 20, 2011

Designing Home Automation For Physically Disabled

It is on full swing now. We made a presentation to TDB Secretary last week and hope to get his approval and funding too.

Sunday, March 20, 2011

My first-break through with Linux - Installing Airtel 3G USB Stick

I recently started working on Linux. First step was easy - just bought Dell Vostro with pre-installed Ubuntu 8.04 and in 30 minutes I was using it for all activities like mail, facebook, blogging and google docs.

The real challenge came 2 days back when I bought AirTel 3G USB Stick for accessing Internet on the move. There was no ready-to-run package on the usb stick or any website or any single post/blog saying how to do it.

It took me six hours on sunday and it worked. So here is the details of the problems and the steps taken by me.

1. When I connect USB stick, ubuntu detects it and add two icons in 'computer' as removable hard disk (a 2 GB SD Memory card allow it to be used as pen drive) and CD ROM (which has programs for Windows and Mac to make it plug and play device).

2. Google search told me that 'lsusb' will tell me the usb device created by it. here is what 'lsusb' produced

Bus 002 Device 003: ID 12d1:1446 Huawei Technologies Co., Ltd.

being a hardware guy I knew that this USB device has vendor id as 12d1 and product id as 1446.

3. Another google search said that  new generation of 3G sticks need a program called usb_modeswitch' to convert usb storgae device to modem.
used following link to download and install

I also knew that we need provide target vendor id and product id. This was not in the installed usb_modeswitch. It had lot of different usb sticks but not the huawei E173 sold by AirTel, 

4. Search for E173 usb_modeswitch gave me following command line 

sudo usb_modeswitch -v 0x12d1 -p 0x1446 -V 0x12d1 -P 0x140c -m 0x01 -M "55534243123456780000000000000011060000000000000000000000000000"

trying this command and then modifying etc/usb_modeswitch.conf to include above parameters to make it simpl to type worked.

I tested it by typing wvdialconf 

5. Last step is to create a network connection. In ubuntu, this is done by


and follow the instructions to create a network connection for AirTel (or any other service provider)

6. Even after you connect to AirTel network, I was not able to browse net as Automatic DNS servers for airtel were not working. Replaced them with OPEN DNS servers - Use and

These can be changed using

SYSTEMS | PREFERENCE | NETWORK CONNECTIONS | Mobile Broadband | Select AirTel 3G | Edit 


My birthday gift - Opportunity to Learn and do some thing different

I completed 50 years  of life this month. I celebrated by doing following

1. Gifted my self a new dell laptop with pre-installed Linux. What is exciting is possibility of me learning and mastering Linux.

2. Visited Sunaay Foundation, promised them a day a month in working with students, made a small financial contribution.

Life is more exciting, creating more results and having more fun.

Planning for next 50 years is on now......... Stay tuned and keep reading my blog.

More about Sunnaya Foundation at