10 min

Convert frequency input into voltage output with exceptional accuracy using VFC32KU and STM32F373RC

Transforming waves into voltage: The future of signal analysis

Hz To V 2 Click with Fusion for STM32 v8

Published Dec 09, 2023

Click board™

Hz To V 2 Click

Development board

Fusion for STM32 v8


NECTO Studio



Translate frequency data into voltage signals, setting a new standard for signal analysis and control



Hardware Overview

How does it work?

Hz to V 2 Click is based on the VFC32KU, a voltage-to-frequency and frequency-to-voltage converter from Texas Instruments. It accepts a signal with the frequency within a range between 200Hz and 120kHz on the input and generates DC voltage with the level corresponding to the input frequency, ranging from 0V to 10V, with a highly linear response. The output DC voltage level is further scaled down by the voltage divider on the VFC32KU output, in order to achieve levels acceptable by the MCU. This makes the DC voltage output suitable for sampling, or further processing by the host MCU. The input signal within the specified frequency range can be applied to either the PWM pin of the mikroBUS™ labeled as FIN on this Click board™ or to the external signal input terminal labeled as FEXT. This signal is AC coupled by a 1nF capacitor, meaning

that no DC component will be affecting the connected source. The signal input source can be selected by the onboard switch, labeled as INPUT SEL. A DC voltage output ranging up to 3.3V is available both on the AN pin of the mikroBUS™ labeled as the VO, and the output terminal - labeled as the VOUT on this Click board™. An onboard high-precision OFFSET potentiometer is used to fine-tune the output of the Click board™. It can be calibrated by using the offset potentiometer, by introducing a signal of a known frequency to either FEXT input terminal or the PWM input pin. An offset trimming procedure should be executed before the first use of the Click board™, since even slight variations in the components tolerances could affect the value at the output. It is recommended to correct the offset after longer time intervals, to compensate

for the aging of the passive components on the Click board™. The VFC32KU IC requires a dual power supply with ±15V. Therefore, this Click board™ utilizes another IC in order to provide the required voltages. It uses the TPS65131, a positive and negative output DC/DC Converter IC, also from Texas Instruments. This DC/DC converter has already been used in Boost-INV 2 click, so it was tested "on the field" for this purpose. Providing well-stabilized output with the plenty of power headroom, it is a perfect solution for the HZ to V 2 click, also. To enable the conversion circuitry, the EN pin of the TPS65131 boost converter should be pulled to a HIGH logic level. This will activate the boost converter and provide the required power for the VFC32KU IC. This pin is routed to the mikroBUS™ CS pin and it is labeled as EN.

Hz To V 2 Click hardware overview image

Features overview

Development board

Fusion for STM32 v8 is a development board specially designed for the needs of rapid development of embedded applications. It supports a wide range of microcontrollers, such as different 32-bit ARM® Cortex®-M based MCUs from STMicroelectronics, regardless of their number of pins, and a broad set of unique functions, such as the first-ever embedded debugger/programmer over WiFi. The development board is well organized and designed so that the end-user has all the necessary elements, such as switches, buttons, indicators, connectors, and others, in one place. Thanks to innovative manufacturing technology, Fusion for STM32 v8 provides a fluid and immersive working experience, allowing

access anywhere and under any circumstances at any time. Each part of the Fusion for STM32 v8 development board contains the components necessary for the most efficient operation of the same board. An advanced integrated CODEGRIP programmer/debugger module offers many valuable programming/debugging options, including support for JTAG, SWD, and SWO Trace (Single Wire Output)), and seamless integration with the Mikroe software environment. Besides, it also includes a clean and regulated power supply module for the development board. It can use a wide range of external power sources, including a battery, an external 12V power supply, and a power source via the USB Type-C (USB-C) connector.

Communication options such as USB-UART, USB HOST/DEVICE, CAN (on the MCU card, if supported), and Ethernet is also included. In addition, it also has the well-established mikroBUS™ standard, a standardized socket for the MCU card (SiBRAIN standard), and two display options for the TFT board line of products and character-based LCD. Fusion for STM32 v8 is an integral part of the Mikroe ecosystem for rapid development. Natively supported by Mikroe software tools, it covers many aspects of prototyping and development thanks to a considerable number of different Click boards™ (over a thousand boards), the number of which is growing every day.

Fusion for STM32 v8 horizontal image

Microcontroller Overview

MCU Card / MCU



8th Generation


ARM Cortex-M4

MCU Memory (KB)


Silicon Vendor


Pin count


RAM (Bytes)


Used MCU Pins

mikroBUS™ mapper

Analog Output
Boost Regulator Enable
Power Supply
Frequency Input

Take a closer look


Hz To V 2 Click Schematic schematic

Step by step

Project assembly

Fusion for PIC v8 front image hardware assembly

Start by selecting your development board and Click board™. Begin with the Fusion for STM32 v8 as your development board.

Fusion for PIC v8 front image hardware assembly
GNSS2 Click front image hardware assembly
SiBRAIN for PIC32MZ1024EFK144 front image hardware assembly
GNSS2 Click complete accessories setup image hardware assembly
v8 SiBRAIN Access MB 1 - upright/background hardware assembly
Necto image step 2 hardware assembly
Necto image step 3 hardware assembly
Necto image step 4 hardware assembly
NECTO Compiler Selection Step Image hardware assembly
NECTO Output Selection Step Image hardware assembly
Necto image step 6 hardware assembly
Necto image step 7 hardware assembly
Necto image step 8 hardware assembly
Necto image step 9 hardware assembly
Necto image step 10 hardware assembly
Necto PreFlash Image hardware assembly

Track your results in real time

Application Output

After pressing the "FLASH" button on the left-side panel, it is necessary to open the UART terminal to display the achieved results. By clicking on the Tools icon in the right-hand panel, multiple different functions are displayed, among which is the UART Terminal. Click on the offered "UART Terminal" icon.

UART Application Output Step 1

Once the UART terminal is opened, the window takes on a new form. At the top of the tab are two buttons, one for adjusting the parameters of the UART terminal and the other for connecting the UART terminal. The tab's lower part is reserved for displaying the achieved results. Before connecting, the terminal has a Disconnected status, indicating that the terminal is not yet active. Before connecting, it is necessary to check the set parameters of the UART terminal. Click on the "OPTIONS" button.

UART Application Output Step 2

In the newly opened UART Terminal Options field, we check if the terminal settings are correct, such as the set port and the Baud rate of UART communication. If the data is not displayed properly, it is possible that the Baud rate value is not set correctly and needs to be adjusted to 115200. If all the parameters are set correctly, click on "CONFIGURE".

UART Application Output Step 3

The next step is to click on the "CONNECT" button, after which the terminal status changes from Disconnected to Connected in green, and the data is displayed in the Received data field.

UART Application Output Step 4

Software Support

Library Description

This library contains API for Hz To V 2 Click driver.

Key functions:

  • hztov2_en_pin - This function enable the click board

  • hztov2_read_voltage - This function read ADC data and converts it to voltage

  • hztov2_fin_set - This function sets PWM clock frequency at FIN pin.

Open Source

Code example

This example can be found in NECTO Studio. Feel free to download the code, or you can copy the code below.

 * \file 
 * \brief HzToV2 Click example
 * # Description
 * This app converts input frequency to a DC voltage output.
 * The demo application is composed of two sections :
 * ## Application Init 
 * This function initializes and configures the logger and the click board.
 * ## Application Task  
 * Sets the PWM frequency then reads the voltage from VO pin and logs all data on USB UART.
 * ## NOTE
 * In order to set PWM frequency below 1 kHz, the user will probably need to lower the main MCU clock frequency.
 * \author MikroE Team
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "hztov2.h"

// ------------------------------------------------------------------ VARIABLES

static hztov2_t hztov2;
static log_t logger;
static float voltage;
static uint32_t fin;

// ------------------------------------------------------ APPLICATION FUNCTIONS

void application_init ( void )
    log_cfg_t log_cfg;
    hztov2_cfg_t cfg;

     * Logger initialization.
     * Default baud rate: 115200
     * Default log level: LOG_LEVEL_DEBUG
     * @note If USB_UART_RX and USB_UART_TX 
     * are defined as HAL_PIN_NC, you will 
     * need to define them manually for log to work. 
     * See @b LOG_MAP_USB_UART macro definition for detailed explanation.
    LOG_MAP_USB_UART( log_cfg );
    log_init( &logger, &log_cfg );
    log_info( &logger, "---- Application Init ----" );

    //  Click initialization.

    hztov2_cfg_setup( &cfg );
    hztov2_init( &hztov2, &cfg );
    hztov2_en_pin( &hztov2, 1 );
    fin = 10000;
    Delay_ms( 100 );

void application_task ( void )
    if ( fin > 120000 )
        fin = 10000;
    hztov2_fin_set( &hztov2, fin );
    log_printf( &logger, "Frequency: %lu Hz \r\n", fin );
    Delay_ms( 100 );
    voltage = hztov2_read_voltage( &hztov2 );
    log_printf( &logger, "Voltage: %.2f V \r\n", voltage );
    fin += 10000;
    Delay_ms( 2000 );

void main ( void )
    application_init( );

    for ( ; ; )
        application_task( );

// ------------------------------------------------------------------------ END

Additional Support