Mega Meter with Multifunctional Features

This Mega Meter project was built around the ATmega128 microcontroller wherein the GCC 3.2 is used to fully program the microcontroller while VB 6 is used to program the PC interface.

An ATmega128 used in the board contains all other basic operational features along with 14.7MHz crystal, ISP interface, RS232 interface, and 5V supply. The need for rail-to-rail op-amps was eliminated by using the 6V supply to allow op-amps to reach about 4.5V while helping to strengthen the input signal and reduce noise by allowing a higher reference voltage than 2.5V. the basic ADC inputs are using two 0-10VDC while the 10V is converted to about 4V by a voltage divider. The display resolution is allowed to be changed by the PC as the AVR decides which step to be used depending on the input voltage.

To amplify incoming signals to the point that triggering occurs, an LM358 op-amp with adjustable gain is used. A 16-bit TCNT3 in external clock mode is used by the frequency counter to count incoming pulses while a 16-bit TCNT1 timer counter in normal mode is used by the frequency generator. As the frequency rises, the accuracy decreases.

Rest of the project