ECG 5 click can be used for the development of ECG and Heart-Rate (HR) applications. The Click board™ features the AD8232, an integrated bio-signal front end. This IC has many features necessary for providing accurate ECG measurements, including very high common-mode rejection ratio, high gain with DC blocking capability, adjustable high-pass and low-pass filters, integrated right leg drive (RLD), etc. Electrodes presence detection pin helps to reduce the overall power consumption, as it can be used to set the standby mode of the host MCU. The fully conditioned bio-signal is available at the analog output to be sampled by an external A/D converter.

ECG 5 click is supported by a mikroSDK compliant library, which includes functions that simplify software development. This Click board™ comes as a fully tested product, ready to be used on a system equipped with the mikroBUS™ socket.

How does it work?

To measure the activity of the heart muscle, it is necessary to extract its weak electrical impulses, reduce the interferences of surrounding tissues and the environment, amplify them, and allow them to be further processed, most likely in the digital domain. Such a task demands very specific instrumentation equipment. ECG 5 click utilizes the AD8232, an integrated heart rate monitoring front-end, by Analog Devices. This IC is targeted towards wearables and battery-operated applications.

The heart-rate impulses are weak by nature and in the range of just a few millivolts, even microvolts. Therefore, any external interference might obscure them. The interferences might be induced in the human body itself, or they might appear as the result of the activity of other muscles, such as skeletal muscles. Therefore, the input signal from the electrodes is processed by several filtering sections, until it is amplified to a value suitable for sampling. However, the correct placement of the measurement electrodes is crucial for accurate readings. More about the electrodes and their placement can be found in this blog article.

ECG 5 click features a 3.5mm jack connector, which is used to connect three electrodes. One of the electrodes is a so-called right leg drive electrode (RLD), used to set the body of the patient to the same potential as the rest of the system. In addition, it is used to reduce the noise which results from the human-body acting as an antenna (picking up 50/60 Hz hum from the mains, etc.) Along with the integrated 2-pole high-pass filtering section, and the RFI filtering section, the IC effectively reduces the overall system noise.

Specifications

Pinout diagram

This table shows how the pinout on ECG 5 click corresponds to the pinout on the mikroBUS™ socket (the latter shown in the two middle columns).

Notes	Pin					Pin	Notes
Analog ECG signal OUT	AN	1	AN	PWM	16	LO-	Lead-off detection for IN-
	NC	2	RST	INT	15	LO+	Lead-off detection for IN+
Chip Enable	SDN	3	CS	RX	14	NC
	NC	4	SCK	TX	13	NC
	NC	5	MISO	SCL	12	NC
	NC	6	MOSI	SDA	11	NC
Power Supply	3.3V	7	3.3V	5V	10	NC
Ground	GND	8	GND	GND	9	GND	Ground

Onboard settings and indicators

Software support

We provide a library for the ECG 5 click on our LibStock page, as well as a demo application (example), developed using MikroElektronika compilers. The demo can run on all the main MikroElektronika development boards.

Library Description

The library performs a device mode setting (Normal or Shutdown) and a leads off detection checking. Also the library initializes GPIO driver. For more details check documentation.

Key functions:

• void ecg5_setMode( uint8_t state ) - The function performs a device mode setting.
• T_ECG5_RETVAL ecg5_check_LOD_negative( void ) - In DC Leads Off Detection Mode, LOD- is high when the electrode to -IN is disconnected, and it is low when connected. In AC Leads Off Detection Mode, LOD- is always low.
• void ecg5_gpioDriverInit(T_ECG5_P gpioObj) - Function initializes GPIO driver.

mikroSDK

This click board is supported with mikroSDK - MikroElektronika 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.

Resources

Downloads