AVR LCD Microcontrolled Oscilloscope circuit

A few months ago as I was surfing on the net, I saw an oscilloscope based on PIC18F2550 microcontroller and a KS0108 controller based graphical LCD. That was Steven Cholewiak’s web site. I had never seen before so amazing microcontroller-only oscilloscope. That was realy impressive circuit, so I decided to design something like that but in C language instead of assembly that I was using all those years. The best solution for me was the WinAVR as it bases on open source AVR-GNU compiler and it works perfect with AVR studio 4. The graphics library that I used, is made by me specific for this project. It’s not for general use. If you want to include it to your codes, you have to convet it as you need to.
The maximum signal speed who can show up this oscilloscope is 5 kHz in square signal. For other signals (sine or triangle) the frequency is lower ( almost 1 kHz) for having clear view of the signal. Description The operating voltage of the circuit is 12V DC. By this voltage, the power supply is producing 2 voltages. +8.2V for IC1 and +5V for IC2 and IC3. This circuit can measure from +2.5V to -2.5V or from 0 to +5V dependent by S1 position (AC or DC input). By using probe with 1:10 division you can measure almost 10 times higher voltages. Moreover, with S2 you can make an extra division by 2 the input voltage. Programming The ATmega32 Burn the ATmega32 with AVR_oscilloscope.hex and select external crystal at the fuses section. After that, you Must disable the JTAG interface from your ATmega32 microController. If you don’t do that, the mega32 will show you the initial screen and when it go to the oscilloscope screen it will restart immediately to the initial screen and it will stay there for ever. Calibrations The only 2 things you have to calibrate is the LCD contrast trimmer P2 and the P1, to move the beam at the center of the LCD. To do that, apply only the power supply to the circuit and adjust the P2 up to the point you will see clear the appeared pixels on the screen. Then, adjust the P1 up to the point the beam is moved at the middle of the LCD (at the horizontal line of the cross). Usage You can move the beam up or down the screen by pressing… http://www.serasidis.gr/circuits/AVR_oscilloscope/avr_oscilloscope.htm
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