In the June issue of Circuit Cellar, George Adamidis, a physicist and electronics engineer from Greece, shares his design for a 1.5-GHz frequency counter.
His design is based on an 8-bit microcontroller, but his modifications enable using the device as a 28-bit counter.
Here is a picture of the complete project.
“This design began as a Microchip Technology 8-bit PIC learning project. But it became more than that,” Adamidis says in his article. “Although I used an 8-bit PIC, I actually created a 28-bit counter.”
“The device measures signal frequencies from 0.1 Hz to 1.5 GHz and displays them on a 2 × 16 character LCD,” Adamidis continues. “It offers a frequency resolution up to 0.1 Hz for frequencies in the 0.1-Hz-to-100-MHz range and up to 4 Hz for 100-MHz-to-1.5-GHz frequencies. (The display resolution generally differs from the measurement accuracy.) Minimum and maximum hold functions, selection of frequency units, and gate time adjustment are also supported. “
Adamidis says it is “remarkable” that his frequency counter is actually a 28-bit counter.
“It uses a Microchip Technology PIC18F2620 microcontroller, which has only 16-bit internal counters. I used the PIC18F2620’s internal 16-bit Timer0 module (configured as a 16-bit counter), an additional 4-bit NXP Semiconductors 74F161 binary counter, and the PIC18F2620’s internal prescaler (in 1:256 prescale mode) in series to achieve a total of 28 bits.”
This is the 1.5-GHz frequency counter’s block diagram.
To read more about the theory of operation, hardware, and software behind Adamidis’s design, check out this month’s issue of Circuit Cellar.