MIKROE ECG/GSR Click is a compact add-on board representing a complete solution for the development of ECG and GSR applications. This board features the AS7030B, a vital sign sensor based on Photoplethysmography (PPG) and Electrocardiogram (ECG) operations from AMS-AG. This vital-sign sensor features a low noise analog front end, a single device integrated optical solution, a synchronous demodulator, and skin temperature and skin resistivity measurements by providing an interface to external NTC. This Click board™ is suitable for medical remote diagnostic equipment applications, such as disposable patches used for blood oxygen saturation (SpO2) and electrocardiogram (ECG) measurement.

NOTE: ECG/GSR Click is a development and prototyping tool. It is not intended to be used for patients' medical treatment and should not be used to diagnose or treat any conditions.

ECG/GSR Click as its foundation uses the AS7030B, a vital sign sensor based on Photoplethysmography (PPG) and Electrocardiogram (ECG) operations from AMS-AG. These two popular methods are suitable for heart rate monitoring (HRM) and heart rate variability (HRV), which measure the pulse rate by sampling light modulated by blood vessels that expand and contract as blood pulses through them. The ECG is the reference for any measurement of the biopotential generated by the heart.

This vital sign sensor features a low noise analog front end, a single device integrated optical solution, and a synchronous demodulator. It consists of two 527nm green LEDs and one 940nm IR LED. The built-in infrared emitter and dedicated photodiode enable easy integration of proximity function. Besides the HRM and SpO2, the AS7030B is also an optical measurement system for GSR (galvanic skin resistivity) and skin temperature obtained via an external temperature sensor connected to an onboard header labeled as NTC.

ECG/GSR Click communicates with MCU using the standard I2C 2-Wire interface that supports Standard-Mode (100 kHz) and Fast-Mode (400 kHz) operation. Also, it uses two additional pins, the INT pin of the mikroBUS™ socket, used as an interrupt, and the EN pin, routed on the CS pin of the mikroBUS™ socket, used to put the AS7030B into Normal operation mode or in a Shutdown. The AS7030B does not require a specific Power-Up sequence but requires a supply voltage of 3.8V to work correctly. Therefore, the Click board™ uses a low dropout linear regulator AP7331 from Diodes Incorporated, providing a 3.8V out of 5V mikroBUS™ rail.

This Click board™ consists of two input channels routed to the 3.5mm jack connectors labeled as ECG and GSR, to which a 1m long ECG/EMG cable connects the electrodes to the appropriate Click board™ securely. The two electrode holders consist of a metal piece with a dent in the middle that perfectly fits the rivets on the electrodes. The contact with the measurement Click board™ remains good and secure while mounting the cable's electrodes is simple and easy.

This Click board™ can operate with both 3.3V and 5V logic voltage levels selected via the VCC SEL jumper. This way, it is allowed for both 3.3V and 5V capable MCUs to use the I2C communication lines properly. However, the 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.

• Interface: I²C
• Compatibility: mikroBUS™
• Dimensions: 57.15 x 25.4mm
• Input Voltage: 3.3V or 5V
• Green LED Wavelength: 527nm
• IR LED Wavelength: 940nm
• ADC Resolution: 14bit
• Relative Accuracy: Min. -8LSB, Max. 8LSB
• Conversion Rate: 50ksps
• Operating Temperature Range: Min. -30°C, Typ. +25°C, Max. +70°C

• Schematic
• AP7331 Datasheet
• AS7030B Datasheet
• mikroSDK
• GitHub