Dr. Sajid Muhaimin Choudhury



I'm Dr. Sajid Muhaimin Choudhruy

I am currently working in the Department of Electrical and Electronic Engineering of Bangladesh University of Engineering and Technology, Dhaka-1205. My official website is located at sajid.buet.ac.bd. I previously maintained various personal blogs and websites (sajidmc.net). I decided to move to a permanent web solution to host all my previous blogposts.


Beginner's Microcontroller Programming-IV: Absolute minimalisticapproach to the modified SIProg

Ok, before I startered this project, I tried to construct the USBasp and USBtiny, and was not successful with bread board. I am planning to make a better version of the USBasp in PCB, but at the moment I tried to make a really small  SI Prog. It will be so small that the entire veroboard will fit into a standard serial port connector casing. I just bought one from Patuatuli:

To fit the veroboard into the small casing, you can maximum fit a 6x6 hole veroboard piece into it, by properly polishing the sides, the central piece could be two hole longer. As the header is inserted into the box, the backside of the header blocks the first row. With only five holes, I thought, at first it would be impossible to fit my circuit (http://sajiduc.blogspot.com/2008/04/beginners-microcontroller-programming.html) here.

Then it occured to me, if I used the extra holes in the middle row to connect the densedly connected ground line, and use the ends of resistors to get connection from the MOSI, SCK, and RESET lines, it will be possible to accomodate the circuit in the header box. And so, here it is, I present you the smallest possible (with non-SMT components) SI Prog. It supports most popular microcontrollers like ATmega16, ATmega32, ATmega8, ATtiny2313, but you probably already know that from my third blog. Circuit diagram is available there:

Microcontroller Based Automatic Object Sorting by Length

I'll give you the circuit description and codes later.

External Crystals and Ponyprog

We are now working on a project that requires external crystal. I borrowed a microcontroller from my friend today. We were using external crystal for our project, and I thought that was no big deal. I brought the microcontroller home, and tried to program it. Ponyprog said it is an unknown device. I was quite anguished and thought that it the microcontroller was fried. Suddenly just for curisity, I plugged in a 12MHz crystal. And wow, ponyprog started working again!

Moral (!!!!) : When you have programmed fusebits for external crystals, you MUST use one (crystal) to program the microcontroller.

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Sajid Choudhury
Dhaka, Bangladesh