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look4kannan
03-27-2008, 05:24 PM
I tried to reset fuse bits of atmega32 using parallel port programmer.

i cant communicate with target.i used ponyprog and below circuit.

Instead of 74HCT541 i used 74LS541.

Is there any correction in circuit?

http://www.kmitl.ac.th/~kswichit/ISP-Pgm3v0/isp1_sch.gif

elecrom
03-29-2008, 10:12 AM
This is simple and sure-shot working circuit (ISP) ... try that ..
Simple AVR programmer (http://elecrom.wordpress.com/2007/10/15/make-your-own-ultra-simple-universal-avr-programmer/)

b_7e72003
03-29-2008, 10:35 PM
Hey thats a great circuit..........

I want to know 1 thing..............I hav burnt a code in to microcontroller

-> now i want to write another program & burn in to the same microcontroller...............so will this circuit work or do we need something else to fuse the bits.

and also Hey I am using ATmega32 so which crystal should I use.

elecrom
03-30-2008, 12:05 AM
Yes you can use this circuit to burn uC again. For fuse bits setting refer another post on fuse bits (http://elecrom.wordpress.com/2007/10/15/configuring-avr-fuse-bits-for-clock-selection/) on this blog. There you will find settings for "ATmega16/32 - external xtal upto 16MHz, full oscillator swing, slow rising power (65ms), JTAG disabled" Use these settings.

Better use 16Mhz xtal for your mega32.

b_7e72003
03-30-2008, 08:13 AM
Hey,

-> I have a new ATmega32 uC can I burn the programme directly or do i need to configure the fuse bits first.

-> Hey 1 more thing you used a crsytal oscillator in designing the circuit so do i need to use a 16MHz oscillator or the oscillator which you have used that is (8Mhz).

-> can u plese explain why we configure the fuse bits??

b_7e72003
03-30-2008, 08:21 AM
& 1 more thing y did u use a ic base in the circuit??

elecrom
03-30-2008, 09:33 AM
& 1 more thing y did u use a ic base in the circuit??
Means ?? Photograph shows programmer made by me ... small IC base is for 20pin AVR, big one is for 40pin AVR. MISO,MOSI,SCK,RESET,X1,X2,VCC,GND of both AVRs sockets are tied up together on the PCB.


-> can u plese explain why we configure the fuse bits??

By default uC ships with internal 1MHz oscillator enabled. If you want to use external crystal (so that you can drive the uC with frequency of your choice) You have to configure fuse bits.

Also, by default JTAG is enabled, thus you cannot use corresponding pins for i/o. You have to disable JTAG if you want to use them. For that you have to unprogram JTAGEN fuse.

You can consider fuse bits like internal switches which controls the certain functionality on the chip.

elecrom
03-30-2008, 09:46 AM
-> I have a new ATmega32 uC can I burn the programme directly or do i need to configure the fuse bits first

No, If you just want to test the uC and want to get feel of mega32 programming, there is no need to change fuse bits. Your brand new mega32 will be configured with internal 1MHz oscillator enabled, mega103 compatibility mode enabled (in which case certain I/Os are not available, refer datasheet), so you don't even need external crystal. You can happily try LED blinking and all those programs which don't really need uC operating more than 1MHz.


-> Hey 1 more thing you used a crystal oscillator in designing the circuit so do i need to use a 16MHz oscillator or the oscillator which you have used that is (8Mhz).

Once fuse bits for Crystal oscillators(for 16MHz) are enabled you can use any crystal from 4MHz to 16MHz for programming. Frequency of the crystal doesn't affect burning process.

b_7e72003
03-30-2008, 04:01 PM
Thank u for evry thing!!!!