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This AVR-based Frequency Meter is capable of measuring frequencies from 1Hz to 10MHz with 1 Hz resolution. The hardware of this project consists of seven 7-segment displays, AVR ATtiny2313 uController, and a few transistors and resistors. The AVR counts input pulses for a precise 1 second interval (generated using the built-in Timer) and displays the result on the multiplexed seven segment LED displays.
AVR frequency meter
Measuring the frequency of a signal may seem to be a simple process of counting pulses, but in order to get better accuracy, few other things should be considered, such as the gating interval and the range of measurement. This tutorial, posted on the pcbheaven.com, briefly describes two typical methods of frequency measurement: Direct Frequency Measuring (DFM) and the Reverse Frequency Measuring (RFM), with their pros and cons.
The shape of the incoming signal may be distorted and of varying amplitude. Therefore, some sort of signal conditioning along with a voltage limiter is required prior to the frequency counter circuit.
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A wide range frequency meter is an useful tool for an electronics lab. This projects describes a frequency meter based on AT90S231 microcontroller that can measure input frequencies up to 50 MHz. The measured frequency is displayed on 6 digit multiplexed seven segment displays.
It uses two external high-speed 8-bit counters (74HC590) in cascade to count the incoming pulses. Depending upon the input frequency, the counting interval for the external counter circuit is changed by the microcontroller for getting better accuracy. The firmware for AT90S231 is provided in C.
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