4-Digit Frequency Counter and Voltmeter

The project is a 4-digit LED voltmeter and frequency counter that was previously based on PIC16C71 but was replaced by 28-pin device PIC16F876.

The PIC16F876 is capable of driving 4-digit LED in multiplexed mode while measuring frequency, power supply voltage, and SWR/PWR signal strength in a bar graph manner. An external LED display driver chip is not needed as well as external data EEPROM since it is already implemented in PIC16F876. A smaller dimension of the counter compared to its previous version is the result of reduction in the number of used chips.

The latest software version supports the measurement of frequency up to 50MHz and power supply voltage in the range of 0V-25.5V. A PWR/SWR bar graph indicator simultaneously displays the measurement of the input voltage and two analog inputs. In case the pushbutton action or frequency change does not occur for a certain time, an automatic display shutdown occurs in power save mode. The pushbutton allows the user to choose between the frequency, bar graph, or supply voltage to be displayed, in operating mode.

Radio amateur and non-commercial use products are using the latest software version of the LED frequency counter.

Rest of the project