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This tutorial shows you how to create circuits in Proteus Isis, simulate them and then create PCB with Proteus.

Proteus is software for microprocessor simulation, schematic capture, and printed circuit board (PCB) design. It is developed by Labcenter Electronics.
The Proteus Design Suite inludes:
* ISIS -- A schematic capture tool with the possibility to simulate programmable ICs like Microchip PIC, Atmel AVR (ATmega8, ATmega32, or ATtiny2313) etc.
*ARES -- for PCB layouts.

The URL for Proteus is http://www.labcenter.co.uk/

Unfortunately, there are few / no good tutorials for Proteus out there, and therefore I took the trouble of making one myself. The tutorial has 3 parts. First part demonstrates Drawing circuits in Proteus Isis. Second part shows how to simulate circuits in Proteus ISIS, and how to export to ARES for making PCB layout. The third video shows Routing and how to print masks for PCB making.

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http://www.esnips.com/web/USBASP/

এই মাস্ক গুলো থমাস ফিচ্যাল এর বানানো ইউ এস বি প্রোগ্রামার এর জন্য আমি বানিয়েছি। (http://www.fischl.de/usbasp/)

I used series resistors with MOSI MISO SCK and RST lines. They are used for protection of the ATmega8 of the programmer. They can be replaced with short circuits like the original design.In my design, the resistors probably causes some rise time issue, so the programmer will not work unless the slow sck jumper is shorted out. And power is not drawn from the USB port, and taken from the external circuit. Reversing polarity of Vcc and GND will certainly cause the programmer to die. I included a Zener Diode in my design to limit the reverse polarity voltage, but don’t know how effective it would be. I’ll try to make another design with 5 wire-output, that draws power from USB port.

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Today, I went to make the PCB of my AVR USB Programmer (USBASP). BUET Students usually go to ‘Toru Bhai’ for making PCBs. I did my design in Proteus Isis and Ares. I talked to Toru Bhai, and he asked me to bring print out of the masks I designed. Basically 3 masks are required for single layer PCB:

Bottom Copper

Top Components (Silk Screen)

Solder Resist

Although, Toru Bhai is reluctant to do the Solder Resist, as he claims it is too expensive. As I went today in his ‘factory’, in 6/1/F, Ram Krishna Mission Road, he didn’t have much work load and insisted me to wait and take my PCB with me. So I watched the fabrication process. Surprisingly, the screen printing is very much similar to VLSI fabrication.

Basically, a thin fabric with tiny holes in it is first covered in paint, and the tracing paper with the print out of the pattern is held in front of it. The screen is enclosed in glass, and exposed to solar light. The region covered by ink in the tracing paper remain unchanged, but the region exposed to light hardened. The screen is then washed, and the region covered by ink on tracing paper during solar exposure has its paint removed.

Then the screen is used to imprint the pattern of the tracing paper on copper board. The paint has to be insoluble to water. After the print, the board is submerged to FeCl3 (Ferric Chloride). Regions not covered by paint has its copper removed, as Copper reacts with FeCl3 to produce Cu-Chloride.

Afterwards, the paint is removed. Then holes are drilled to it, and the top layer patterns are drawn accordingly.

I got some pictures of the process:

The lab:

A screen looks like this:

Fitting the screen

Screen ready for action

Patternizing

FeCl3 Etching

Drilling Holes

Grinder used to smoothen the sides

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Finally I could get my USB programmer to work with windows vista. Firstly, I stripped of the breadboard from all previous connections, and reconnected the circuit. This ofcourse proved fatal to two of my microcontrollers, as I accidentally connected +12V to Vcc rail, instead of the input to the 7805 IC. I connected the programmer to PC, and it said unknown device. I knew I connected the D+ and D- wires from USB port wrong. The final bread board looks like this:

So I swapped them and replugged the USB. This time the device was recognised as usbasp, and windows vista asked for driver. I supplied the libusb driver given with the fischel’s package (http://www.fischl.de/usbasp/). Windows said something about device compatibiliy. I chose to ignore, and the device installed successfully.

Now I opened command prompt and typed avrdude -c usbasp -p t2313

Command prompt returned error: could not find USB device “USBasp” with vid=0x16c0 pid=0x5dc

I tried to search the forums. They suggested to use 2007 build of winavr, I tried that (replaced avrdude.exe in the C:\winavr\bin directory with the 2007 version). Some of them also suggested to use an older version of libusb. So I did that too. After spending an hour, I did some thing I should have done a long time ago. I clicked on the orb (start), typed ‘cmd’, so Vista start menu searched cmd.exe. I right clicked on it and selected “Run as Administrator”. Now when I typed

C:\Windows\system32>avrdude -c usbasp -p t2313

found 8 busses

avrdude: AVR device initialized and ready to accept instructions

Reading | ################################################## | 100% 0.02s

avrdude: Device signature = 0x1e910a

avrdude: safemode: Fuses OK

avrdude done. Thank you.

Wow, the device actually worked!! I tried several times and it was working. I started the AVR8-Burn-O-Mat and changed some settings.

Burn O Mat seems to work fine too. Just too bad it doesn’t have the buffer of ponyprog, and the hex display. It is just great otherwist, and has a lot better fusebit editor.

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http://sajiduc.blogspot.com/2008/04/beginners-microcontroller-programming.html

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 6×6 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:

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

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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 to program the microcontroller.

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Update: My Programmer is working now. Read Here.

My laptop does not have serial port. And ponyprog, up until now, have not provided support for any USB programmers. Today, I constructed my first USB programmer on a breadboard. I had a old USB extenstion cable which was out of order as the header was slack due to wear. I cut of that part and soldered breadboard wires.

My first goal was to make a ponyprog compatible programmer that emulates parallel port. I started with: USB2LPT

Afterwards, I realized that the emulation makes programming too slow. Thus I had to move to a dedicated programmer. But I really like a GUI for inputting, especially the fusebits. AVRdude is a command prompt based programmer. A wrong fusebit setting can lock the microcontroller irrepairable by a Serial Programmer.

Then I found AVR8 Burn-O-Mat: GUI for avrdude . The interface is even better than pony prog for fuses. It actually has small comments beside fusebits. AVRdude even supports my simplified SIProg. So I proceeded to make the famous USB ASP (http://www.fischl.de/usbasp/) I forgot to connect the ICP and INT0 at first, and kept getting “Unknown USB device”. I reflashed 4 times. Finally the programmer was operational and the driver was installed successfully.

I’ll give details of my schematics later. Here is a picture of the circuit.

Update: My Programmer is working now. Read Here.

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