PWR Meter 3 Click

How does it work?

PWR Meter 3 Click is based on the ACS37800, a simple solution for voltage, current, and power monitoring from Allegro MicroSystems, which simplifies the addition of power monitoring in 60Hz to many AC/DC applications. The ACS37800 includes a copper conduction path that generates a magnetic field proportional to the applied current, sensed differentially to reject errors introduced by common mode fields. It is particularly well suited for high isolation, achieving reinforced isolation ratings of 4800 VRMS and a reliable ±90A bidirectional current sensing range. With high configurability and integrated features, this Click board™ can fit most power monitoring applications.

The ACS37800 measures the voltage applied to the REF terminal, in the range from 9.5 to 27V, by resistor dividing it down to fit the input range of the onboard voltage sense amplifier and add isolation. On the other hand, the current applied to the current sensing terminals is measured using the integrated current loop and galvanically isolated Hall sensor. Both analog signals are then sampled using integrated high-accuracy ADCs before entering the digital system. The metrology engine later determines the frequency, calculates RMS values of current, voltage, and power, and provides a range of averaging and configuration options.

PWR Meter 3 Click communicates with MCU using the standard I2C 2-Wire interface to read data and configure settings, supporting Standard Mode operation with a clock frequency of 100kHz and Fast Mode up to 400kHz. The ACS37800 can be enabled or disabled through the EN pin routed to the RST pin of the mikroBUS™ socket, hence, offering a switch operation to turn ON/OFF power delivery to the ACS37800 via TPS2041B.

Along with the ability to measure current and voltage, it also has two LED indicators, DIO0 and DIO1, for the realization of visual detection of some anomalies in operation, such as undervoltage and overvoltage reporting, and fast overcurrent fault detection. The DIO0 LED default state application is for zero crossing, while DIO1 stands for overcurrent detection. In addition to the LEDs, this information can also be detected through the INT and AN pins of the mikroBUS™ socket, marked as D0 and D1.

This Click board™ can be operated only with a 3.3V logic voltage level. The board must perform appropriate logic voltage level conversion before using MCUs with different logic levels. However, the Click board™ comes equipped with a library containing functions and an example code that can be used as a reference for further development.

Specifications

Pinout diagram

This table shows how the pinout on PWR Meter 3 Click corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns).

Notes	Pin					Pin	Notes
Overcurrent	D1	1	AN	PWM	16	NC
Enable	EN	2	RST	INT	15	D0	Zero Crossing
	NC	3	CS	RX	14	NC
	NC	4	SCK	TX	13	NC
	NC	5	MISO	SCL	12	SCL	I2C Clock
	NC	6	MOSI	SDA	11	SDA	I2C Data
Power Supply	3.3V	7	3.3V	5V	10	NC
Ground	GND	8	GND	GND	9	GND	Ground

Onboard settings and indicators

PWR Meter 3 Click electrical specifications

Software Support

We provide a library for the PWR Meter 3 Click as well as a demo application (example), developed using Mikroe compilers. The demo can run on all the main Mikroe development boards.

Package can be downloaded/installed directly from NECTO Studio Package Manager(recommended), downloaded from our LibStock™ or found on Mikroe github account.

Library Description

This library contains API for PWR Meter 3 Click driver.

Key functions

• pwrmeter3_get_dio0_pin This function returns the DIO0 pin logic state.

• pwrmeter3_get_dio1_pin This function returns the DIO1 pin logic state.

• pwrmeter3_read_average_rms This function reads the voltage and current RMS measurements averaged from a specified number of samples.

Example Description

This example demonstrates the use of PWR Meter 3 Click board™ by reading and displaying the voltage, current, and power RMS measurements.

void application_task ( void ) 
 { 
     float v_rms, i_rms; 
     if ( PWRMETER3_OK == pwrmeter3_read_average_rms ( &pwrmeter3, &v_rms, &i_rms, PWRMETER3_DEF_AVG_SAMPLES ) ) 
     { 
         if ( !pwrmeter3_get_dio0_pin ( &pwrmeter3 ) ) 
         { 
             log_printf ( &logger, " Over-voltage detected!rn" ); 
         } 
         if ( !pwrmeter3_get_dio1_pin ( &pwrmeter3 ) ) 
         { 
             log_printf ( &logger, " Under-voltage detected!rn" ); 
         } 
         log_printf ( &logger, " Voltage: %.2f Vrn", v_rms ); 
         log_printf ( &logger, " Current: %.2f Arn", i_rms ); 
         log_printf ( &logger, " Power: %.2f Wrnn", i_rms * v_rms ); 
     } 
 }

The full application code, and ready to use projects can be installed directly from NECTO Studio Package Manager(recommended), downloaded from our LibStock™ or found on Mikroe github account.

Other Mikroe Libraries used in the example:

• MikroSDK.Board
• MikroSDK.Log
• Click.PWRMeter3

Additional notes and informations

Depending on the development board you are using, you may need USB UART click, USB UART 2 Click or RS232 Click to connect to your PC, for development systems with no UART to USB interface available on the board. UART terminal is available in all Mikroe compilers.

mikroSDK

This Click board™ is supported with mikroSDK – Mikroe Software Development Kit. To ensure proper operation of mikroSDK compliant Click board™ demo applications, mikroSDK should be downloaded from the LibStock and installed for the compiler you are using.

For more information about mikroSDK, visit the official page.