Thursday, August 23, 2007

[AVR Programmer] (Further) Simplification ofthe LancOs's SI Prog the Serial Port Porgrammer

Thanks to all of you who tried my previous version of SI prog. One of my friends tried to implement it on his vero-board and it did not work. I gave him my previous one to test. Now there is a Curfew going on in Bangladesh so I could not get his one. So I tried to rebuild the previous circuit. It just did not work! I was flummoxed, and spent a whole day on it. Today I took a good look at the LancOs circuit and found out that they uses two separate reset lines, one through the collector of a BJT, and the another directly through a Zener Diode regulator. In my second circuit, I had omitted the sener regulator part, and had just used the BJT. Luckily I kept some extra space in my vero-board this time, and added the extra resistor and zener diode regulator. I was all out of 4.7K resistors and can’t go to the shop right now (because of the curfew), so I used 1.7Ks merely hoping that they would not fry my serial port. I disconnected the previous reset line (through the BJT) and connected the zener regulated version to the bread board, and it works!!! So I think for microcontrollers not having non inverted reset, this simpler circuit would be just fine.

My previous vero-board plan had errors, so I would not dare to make another one this time. My new veroboard is also not optimized, so I am not uploading any pictures. The entire circuit can be fitted inside a DB9 connector I believe. So AVR fans, please try it out. I’ll try to make a version like that when I manage to get some helping hands. (I am terrible when it comes to soldering.)
Please note that you are trying these circuits AT YOUR OWN RISK. Please don’t come back to me crying you have fryed your serial port, mother board, or the microcontroller. I take absolutely no responsibilities for any injuries or equipment damages.