VU Meter Click is a compact add-on board representing a volume unit meter that displays the intensity of an audio signal. This board features the LM3914, a monolithic integrated circuit that senses analog voltage levels and drives a 10-segment bar graph display from Texas Instruments. This Click board™ is manufactured with a sound detecting device (microphone), Op-Amp, and the LM3914, which gleams the bar graph display according to the sound’s quality. The LM3914 is an analog-controlled driver meaning it can control (turn ON or OFF) a display by an analog input voltage and eliminates the need for additional programming. This Click board™ is commonly used in visual alarms and other metering or monitoring applications.

VU Meter Click is supported by a mikroSDK compliant library, which includes functions that simplify software development.

VU Meter Click as its foundation uses the LM3914, a monolithic integrated circuit that senses analog voltage levels and drives a 10-segment bar graph display from Texas Instruments, making this solution a compact volume unit meter. This is an analog-controlled driver meaning it can control display by an analog input voltage and eliminates the need for additional programming. A volume unit meter represents a device that displays the intensity of an audio signal; more specifically, it is used to visualize analog signals. That’s why VU Meter Click is suitable as a volume measurement gadget.

The LM3914 is configured to work in bar mode where all parts of the bar graph display below a certain point turn on. This board is manufactured with an onboard sound detecting device (microphone), the MC33072 Op-Amp, and the LM3914, which gleams the bar graph display according to the sound’s quality. In the beginning, the microphone captures the sound and transforms it into voltages linear to sound amplitude. The capacitor then stops the DC component of the transmission, allowing the AC input from the microphone to enter the MC33072 Op-Amp.

One part of the MC33072 represents a variable gain inverting amplifier using the TPL0501, an SPI-configurable digital potentiometer from Texas Instruments, while the second part represents a signal buffer. After filtration and amplification, these filtered and amplified signals are finally provided to LM3914. Considering that this driver is analog controlled, this Click board™ also provides the ability to monitor the analog signal by the MCU via the AN pin of the mikroBUS™ socket.

The LM3914 operates in a voltmeter format and lights the XGURUGX10D, a ten-segment bar graph array, according to the strength of the given signal. The onboard bar graph display segments are bright and uniformly colored, providing pleasant and clean visual feedback. Each segment is composed of green and red-colored LEDs, making it possible to have various essential states marked in a different color. It can use green, red, and a combination of these two, resulting in having amber-colored segments.

This Click board™ can operate with both 3.3V and 5V logic voltage levels selected via the VCC SEL jumper. This way, it is allowed for both 3.3V and 5V capable MCUs to use the communication lines properly. However, the Click board™ comes equipped with a library that contains easy-to-use functions and an example code that can be used, as a reference, for further development.

• Interface: Analog, SPI
• Compatibility: mikroBUS™
• Dimensions: 57.15 x 25.4mm
• Input Voltage: 3.3V or 5V
• Maximum Output Current: Min. 2mA, Typ. 10mA, Max. 30mA
• Operating Temperature Range: Min. 0°C, Typ. +25°C, Max. +70°C

• Schematic
• LM3914 Datasheet
• MC33072 Datasheet
• TPL0501 Datasheet
• mikroSDK
• LibStock