V to Hz 2 Click Board™

Product Code: MIKROE-3131

This device is well suited to be used in a number of various voltage to frequency applications: it can be used in instrumentation applications, industrial, and automation markets. It is well suited for use in AD conversion, long-term integration, linear frequency modulation, voltage-to-frequency conversion and it can be used as the variable clock signal generator. Its function can be complemented by the V to Hz 2 Click Board™, which does the opposite type of conversion: frequency into DC voltage. This can be utilized to build an FM modulator/demodulator application, for example. How Does The V to Hz 2 Click Board™ Work? The main component of the V to Hz 2 Click Board™ is the VFC32KU, a voltage-to-frequency and frequency-to-voltage converter from Texas Instruments. It accepts voltage at its input and generates a pulse train, with a frequency linearly proportional to the input voltage. The pulse train is routed to a screw terminal labelled as FOUT, as well as the mikroBUS™ INT pin, labelled as FO.

The signal can be then further processed by the host MCU. When the V to Hz 2 Click Board™ is operated for the first time, it needs to be calibrated. The click is equipped with two variable resistors for gain and offset fine-tuning. A calibration 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™. It is done by introducing a known voltage at the input, and adjusting the gain and the offset, until the signal with the expected frequency appears on the output. As already discussed, V to Hz 2 click is equipped with the input voltage terminal (VEXT), which is used to connect the control voltage up to 3.3V. Besides having control voltage input on this terminal, it is possible to select the voltage generated by the MCU as the control voltage input, too. INPUT SEL switch can be set so that the PWM pin from the mikroBUS™ is used as the control voltage input. The PWM signal generated by the MCU is filtered out by the onboard low pass filter so that the control voltage remains constant. 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, 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 V to Hz 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 labelled as EN. SPECIFICATIONS Type Measurements Applications The V to Hz 2 Click Board™ is well suited for use in A/D conversion, long-term integration, linear frequency modulation, voltage-to-frequency conversion and it can be used as the variable clock signal generator On-board modules VFC32KU, a voltage-to-frequency and frequency-to-voltage converter from Texas Instruments; TPS65131, a positive and negative output DC/DC Converter, from Texas Instruments Key Features Operation up to 500kHz, voltage or current input, excellent linearity Interface GPIO,PWM Compatibility mikroBUS Click board size M (42.9 x 25.4 mm) Input Voltage 3.3V ONBOARD JUMPERS AND SETTINGS Label Name Default Description LD1 PWR - Power LED indicator SW1 INPUT SEL Left Input signal source selection: left position mikroBUS™ FIN pin, right position FEXT input terminal TB1 FOUT - Converted AC voltage output TB2 VEXT - External DC input signal PINOUT DIAGRAM This table shows how the pinout of the V to Hz 2 Click Board™ corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns). Notes Pin Pin Notes NC 1 AN PWM 16