Advanced heart monitoring with MCP609 and MK64FN1M0VDC12
Real-time heart analysis
Published Jul 01, 2023
Click board™
ECG Click
Dev. board
Clicker 2 for Kinetis
Compiler
NECTO Studio
MCU
MK64FN1M0VDC12
Enhance your safety and well-being by providing accurate and reliable information about your heart's electrical activity
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Hardware Overview
How does it work?
ECG Click is based on two MCP609s, a micropower CMOS operational amplifier from Microchip. These are unity-gain stable, rail-to-rail output swing operational amplifiers with a low offset voltage and input bias current designed to prevent phase reversal when the input pins exceed the supply voltages. ECG Click has a seven-block design. It comprises ESD, overvoltage and overcurrent protection (protecting both the hardware and the user), a pre-amplifier and amplifier, two high-pass filters, a low-pass filter, and a DRL circuit. When the electrical signal from the heart reaches the skin's surface, it becomes significantly faint, measuring only a few millivolts. However, this weak signal faces further obstruction due to muscle activity originating from different body parts. Additionally, electromagnetic interference from the surrounding environment, where the body can act as an antenna, presents another noise source. An onboard 3.5mm phone jack connects cables/electrodes to the Click board™.
The electrode collects voltage from the skin, after which the signal is amplified and filtered and then sent to the analog AN pin of the host MCU over the mikroBUS™ socket. The three electrodes should be placed on the left arm, right arm, and the left side of the abdomen (below the heart), on the left leg. ECG Click has one jumper and a trimmer potentiometer for setting the output voltage to match the input voltage level of the ADC, which will be used (10-bit ADC - 12-bit recommended). As a reference, it uses the MAX6106, a low-cost, micropower, low-dropout, high-output-current voltage reference from Analog Devices. The SMD (0805) jumper determines its output voltage range. When connecting all three electrodes, the output should be a constant voltage (1.024V or 2.048V, depending on the jumper position). The trimmer potentiometer is for adjusting the gain. So, if you set the jumper to the 2.048 position (zero is now 1.024V), the gain will be set so that the ECG
waveform is in the range of 0-2.048V. If you set the jumper to the 4.096 position (zero is now 2.048V), the gain will be set so that the ECG waveform is in the range of 0-4.096V. The final measurement results can be displayed as an Electrocardiogram using a free app, the MikroPlot, a free data visualization tool (Windows). It's a simple tool to help you visualize sensor data recorded over time, suitable for biosignals (ECG, EEG, EMG) and environmental data logging (temperature, humidity, and more). The app can receive data sets from a microcontroller through a USB UART connection. This Click board™ can only be operated with a 5V 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.
Features overview
Development board
Clicker 2 for Kinetis is a compact starter development board that brings the flexibility of add-on Click boards™ to your favorite microcontroller, making it a perfect starter kit for implementing your ideas. It comes with an onboard 32-bit ARM Cortex-M4F microcontroller, the MK64FN1M0VDC12 from NXP Semiconductors, two mikroBUS™ sockets for Click board™ connectivity, a USB connector, LED indicators, buttons, a JTAG programmer connector, and two 26-pin headers for interfacing with external electronics. Its compact design with clear and easily recognizable silkscreen markings allows you to build gadgets with unique functionalities and
features quickly. Each part of the Clicker 2 for Kinetis development kit contains the components necessary for the most efficient operation of the same board. In addition to the possibility of choosing the Clicker 2 for Kinetis programming method, using a USB HID mikroBootloader or an external mikroProg connector for Kinetis programmer, the Clicker 2 board also includes a clean and regulated power supply module for the development kit. It provides two ways of board-powering; through the USB Micro-B cable, where onboard voltage regulators provide the appropriate voltage levels to each component on the board, or
using a Li-Polymer battery via an onboard battery connector. All communication methods that mikroBUS™ itself supports are on this board, including the well-established mikroBUS™ socket, reset button, and several user-configurable buttons and LED indicators. Clicker 2 for Kinetis is an integral part of the Mikroe ecosystem, allowing you to create a new application in minutes. Natively supported by Mikroe software tools, it covers many aspects of prototyping thanks to a considerable number of different Click boards™ (over a thousand boards), the number of which is growing every day.
Microcontroller Overview
MCU Card / MCU
Architecture
ARM Cortex-M4
MCU Memory (KB)
1024
Silicon Vendor
NXP
Pin count
121
RAM (Bytes)
262144
You complete me!
Accessories
3-wire ECG/EMG cable comes with a convenient 3.5mm phone jack, and it is designed for electrocardiogram recording. This 1m cable is a practical companion for medical professionals and enthusiasts. To complement this cable, you can also use single-use adhesive ECG/EMG electrodes measuring 48x34mm, each equipped with an ECG/EMG cable stud adapter. These electrodes ensure a seamless experience when paired with our ECG/EMG cable and guarantee reliable ECG/EMG signal transmission for comprehensive cardiac monitoring. Trust in the accuracy and convenience of this setup to effortlessly record electrocardiograms and electromyograms with confidence.
Used MCU Pins
mikroBUS™ mapper
Take a closer look
Click board™ Schematic
Step by step
Project assembly
Start by selecting your development board and Click board™. Begin with the Clicker 2 for Kinetis as your development board.
Track your results in real time
Application Output
1. Application Output - In Debug mode, the 'Application Output' window enables real-time data monitoring, offering direct insight into execution results. Ensure proper data display by configuring the environment correctly using the provided tutorial.
2. UART Terminal - Use the UART Terminal to monitor data transmission via a USB to UART converter, allowing direct communication between the Click board™ and your development system. Configure the baud rate and other serial settings according to your project's requirements to ensure proper functionality. For step-by-step setup instructions, refer to the provided tutorial.
3. Plot Output - The Plot feature offers a powerful way to visualize real-time sensor data, enabling trend analysis, debugging, and comparison of multiple data points. To set it up correctly, follow the provided tutorial, which includes a step-by-step example of using the Plot feature to display Click board™ readings. To use the Plot feature in your code, use the function: plot(*insert_graph_name*, variable_name);. This is a general format, and it is up to the user to replace 'insert_graph_name' with the actual graph name and 'variable_name' with the parameter to be displayed.
Software Support
Library Description
This library contains API for ECG Click driver.
Key functions:
ecg_generic_read- This function read ADC dataecg_default_cfg- This function executes default configuration for ECG Clickecg_init- This function initializes all necessary pins and peripherals used for ECG Click
Open Source
Code example
The complete application code and a ready-to-use project are available through the NECTO Studio Package Manager for direct installation in the NECTO Studio. The application code can also be found on the MIKROE GitHub account.
/*!
* \file
* \brief Ecg Click example
*
* # Description
* This example demonstrates the use of ECG Click board.
*
* The demo application is composed of two sections :
*
* ## Application Init
* Initializes Click board.
*
* ## Application Task
* Reads ADC sends results on serial plotter.
*
*
* \author MikroE Team
*
*/
// ------------------------------------------------------------------- INCLUDES
#include "board.h"
#include "log.h"
#include "ecg.h"
// ------------------------------------------------------------------ VARIABLES
static ecg_t ecg;
static log_t logger;
static uint16_t read_adc;
static uint32_t time_read;
// ------------------------------------------------------- ADDITIONAL FUNCTIONS
void plot_res ( uint16_t plot_data, uint32_t plot_time )
{
log_printf( &logger, "%u,%u \r\n", plot_data, plot_time);
}
// ------------------------------------------------------ APPLICATION FUNCTIONS
void application_init ( void )
{
log_cfg_t log_cfg;
ecg_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.
ecg_cfg_setup( &cfg );
Delay_ms( 200 );
ECG_MAP_MIKROBUS( cfg, MIKROBUS_1 );
ecg_init( &ecg, &cfg );
Delay_ms( 200 );
time_read = 0;
}
void application_task ( void )
{
time_read++;
read_adc = ecg_generic_read( &ecg );
plot_res( read_adc , time_read);
Delay_ms(5);
}
void main ( void )
{
application_init( );
for ( ; ; )
{
application_task( );
}
}
// ------------------------------------------------------------------------ END
