Intermediate
30 min

Improve your AC measurement with MCP3201 and PIC18F57Q43

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AC Current Click with UNI-DS v8

Published Aug 10, 2023

Click board™

AC Current Click

Development board

UNI-DS v8

Compiler

NECTO Studio

MCU

PIC18F57Q43

Harness our advanced AC measurement solution to optimize power usage, enhance safety, and elevate efficiency across diverse applications

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Hardware Overview

How does it work?

AC Current Click is based on the MCP607, a micropower CMOS operational amplifier from Microchip. The non-invasive sensor that should be used along this Click board™ works by utilizing the electromagnetic induction phenomenon, similar to a transformer. The primary coil does not exist, though; the electromagnetic field is generated by the AC Current running through the cable, which is measured. The core of the sensing probe is split, allowing it to clamp on the current conducting cable. Since the sensor does not influence the measurement circuitry in any way while being galvanically isolated simultaneously, it is an ideal solution to measure current running through mains or similar high-voltage installations. Note that only the AC current can be measured since the DC current cannot generate the alternating magnetic field, so the sensor can only be used for the AC current measurement. The Click board™ comes equipped with the 3.5mm jack connector, which is used to attach the sensing probe. The sensor input is filtered and amplified over the MCP607 so that the readings can stay reliable and protected against EMI and radio interference. The reference voltage for the conversion is 2.048V, and the MAX6106, a voltage reference from Analog Devices

provides it. It samples the input voltage generated by the contactless, non-invasive current sensor attached to the 3.5mm jack connector. This allows a minimal distortion of the input. The amplification ratio (G) is calculated using the non-inverting operational amplifier configuration formula: G = 1 + R4 / R3. Knowing the maximum voltage of the sensor (for 10A current), the reference voltage of 2.048V for the ADC, and the gain factor of the op-amp, it is easy to calculate the value for the measured current. The Click board™ comes with library functions that do all the necessary calculations, providing a simple and quick solution for application development. A user can also easily develop his methods and functions using existing ones if some other sensor with different nominal values is used. However, this Click board™ also comes as part of the AC Current click - bundle, which also contains the current measuring sensor calibrated and well suited to work with the AC Current click (10A - 1V). AC Current Click uses a standard 3-Wire (read-only) SPI serial interface of the MCP3201 to communicate with the host MCU. Besides the onboard A/D converter, an analog signal path is available to the users, allowing the board™ to fit into various usage scenarios. Besides

the onboard ADC, it is possible to use an external converter by using the AN pin of the mikroBUS™. The preconditioned voltage from the first (non-inverting) operational amplifier is routed to the onboard ADC and another op-amp, which acts as the buffer with unity gain. It provides a buffered analog voltage at the AN pin, which can be used externally, bypassing the onboard ADC. The MCP607 consists of two integrated op-amps, so the same IC is used both for the input preconditioning and the output buffer. Note that although the Click board™ is meant to measure current without making contact using a galvanically isolated sensor over an isolated cable, special care should always be taken when working with dangerous voltages. Any operation which involves high voltage should be performed by trained personnel. This Click board™ can operate with either 3.3V or 5V logic levels selected via the VCC SEL jumper. This way, both 3.3V and 5V capable MCUs can use the communication lines properly. Also, this Click board™ comes equipped with a library containing easy-to-use functions and an example code that can be used, as a reference, for further development.

AC Current Click hardware overview image
AC Current Click Current Warning image

Features overview

Development board

UNI-DS 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 STM32, Kinetis, TIVA, CEC, MSP, PIC, dsPIC, PIC32, and AVR MCUs 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, UNI-DS v8 provides a fluid and immersive working experience, allowing access anywhere and under any

circumstances at any time. Each part of the UNI-DS 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. UNI-DS 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.

UNI-DS v8 horizontal image

Microcontroller Overview

MCU Card / MCU

default

Type

8th Generation

Architecture

PIC

MCU Memory (KB)

128

Silicon Vendor

Microchip

Pin count

48

RAM (Bytes)

8196

You complete me!

Accessories

The AC Current sensor is a non-invasive device designed for measuring alternating current. This split-core sensor can easily clip around live or neutral wires, making it versatile for various applications. It finds utility in the current measurement, monitoring, and protection of AC motors, lighting equipment, and air compressors. Key features of this sensor include an open size of 13mm x 13mm, a leading wire length of 1m, and a dielectric strength of 1000V AC/1min 5mA between the shell and output. It operates within a temperature range of -25°C to +70°C, adhering to a resistance grade of Grade B. The built-in sampling resistance (RL) is 186Ω, boasting a non-linearity of ±3%. The output mode ranges from 0 to 1V, accommodating input currents from 0 to 10A AC. With a fire resistance property in accordance with UL94-VO, this AC Current sensor ensures reliable and safe current monitoring in diverse electrical applications.

AC Current Click accessories image

Used MCU Pins

mikroBUS™ mapper

Analog Output
PD4
AN
NC
NC
RST
SPI Chip Select
PE0
CS
SPI Clock
PC3
SCK
SPI Data OUT
PC4
MISO
NC
NC
MOSI
Power Supply
3.3V
3.3V
Ground
GND
GND
NC
NC
PWM
NC
NC
INT
NC
NC
TX
NC
NC
RX
NC
NC
SCL
NC
NC
SDA
Power Supply
5V
5V
Ground
GND
GND
1

Take a closer look

Schematic

AC Current 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 UNI-DS 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 AC Current Click driver.

Key functions:

  • accurrent_get_a - Gets current value of AC Current in A

  • accurrent_get_ma - Gets current value of AC Current in mA.

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 AcCurrent Click example
 * 
 * # Description
 * This application measures AC current through a conductor.
 *
 * The demo application is composed of two sections :
 * 
 * ## Application Init 
 * SPI driver and click initialization.
 * 
 * ## Application Task  
 * Reads the value of AC current and displays it on the USB UART.
 * 
 * ## NOTE
 * An appropriate AC Current sensor needs to be connected to the click board.
 * 
 * \author MikroE Team
 *
 */
// ------------------------------------------------------------------- INCLUDES

#include "board.h"
#include "log.h"
#include "accurrent.h"

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

static accurrent_t accurrent;
static log_t logger;

void application_init ( void )
{
    log_cfg_t log_cfg;
    accurrent_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.

    accurrent_cfg_setup( &cfg );
    ACCURRENT_MAP_MIKROBUS( cfg, MIKROBUS_1 );
    accurrent_init( &accurrent, &cfg );
}

void application_task ( void )
{
    float ac_current;

    ac_current = accurrent_get_ma( &accurrent );
    log_printf( &logger, "Current value: %.3f mA\r\n", ac_current );
    Delay_ms( 1000 );
}

void main ( void )
{
    application_init( );

    for ( ; ; )
    {
        application_task( );
    }
}


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

Additional Support

Resources